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Changes in cancer incidence in the Swiss canton of Vaud, 1978–87
Annals of Oncology 1:29^-297, 1990. O 1990 Kluwer Academic Publishers. Printed in the Netherlands.
Original article Changes in cancer incidence in the Swiss canton of Vaud, 1978-87 F. Levi,L2 V.C. Te1 & C. La Vecchia2-3 l
Registre Vaudois des Tumeurs, CHUV BH-06, Lausanne, Switzerland; 2Inslitut universitaire de midecine sociale et preventive, Lausanne, Switzerland; ^Istituto di Ricerche Farmacologiche 'Mario Negri', Milan, Italy
Summary. Changes in age-standardized cancer registration rates in the Swiss Canton of Vaud (population 530,000) over the two five-year calendar periods 1978-82 and 1983-87 were analyzed. The incidence of occurrence at lung and other tobacco-related sites remained stable (or slightly decreased in males), but showed a substantial increase in females (approximately 40%, from 6.8 to 9.5/100,000 world standard, for lung alone). Other upward trends were observed for skin in both sexes (approaching 50% for melanoma in males), female breast (+8.0%, reaching 69.5/100,000), ovary and urinary tract neoplasms. In contrast, declines were observed not only for stomach and cervix, but also for intestine, gallbladder and endometrium. Consequently, overall total cancer incidence (excluding non-melanomatous skin) declined by 1.1% in males, but increased by 2.7% in females, reaching values of 277.9 and 205.4/100,000, respectively, in 1983-87. The absence of any substantive trends in incidence for cancers of the prostate, testis, brain and multiple myeloma is of potential interest, and represents an important indicator of the uniformly high standard of monitoring by this cancer registration scheme. In a public health perspective, it is discouraging that most of the increases were restricted to cancer sites whose etiology has long been well defined, i.e., tobacco for females and sunshine or other sources of non-ionising radiation, although it is reassuring to be able to document the levelling of tobacco-related cancer incidence in males. Key words: descriptive epidemiology, cancer incidence, cancer registration, time trends
ring in the resident population of the Canton (about 530,000 inhabitants in 1980) [10]. It began operation in Trends in cancer rates have usually been studied in relation January 1972, and the registration scheme was to mortality data, because mortality statistics have been progressively implemented during the first few years folavailable longer than incidence statistics, and are also more lowing its inception. reliable in various aspects and situations, as they are less The registry is tumour-based and multiple primaries ocaffected by improvements in detection, diagnosis and cer- curring in the same person are entered separately. However, tification [1-5]. Cancer registration data, on the other hand, multiple non-melanomatous skin tumours are classified by have major advantages in terms of a standardized quality of site of first recognized tumour of the same morphological information and a high rate of histo-pathological confirma- type. Notification is based on a voluntary agreement tion. Moreover, their trends over time are not influenced by between the recording medical institutions of the Canton changes in treatment nor, therefore, survival rates [6]. Thus, and the Registry. incidence data can, in principle, offer important informaThe main information available from the register comtion [7], although their value and contribution to analysis of prises socio-demographic characteristics of the patient (i.e., trends in cancer rates are still under discussion [1, 6]. age, sex), primary site and histological type of the tumour As a specific contribution to this debate, in this article according to the standard International Classification of we discuss changes in incidence rates from the Cancer Diseases for Oncology (ICD-O) and time of confirmation. Registry of the Swiss Canton of Vaud between 1978 and Passive and active follow-up information is recorded and 1987. For several complex situations and cancer sites (e.g., each subsequent item of information concerning an already skin, or brain [8, 9]) this Registry operates in a particularly registered case is used to complete the record of that favourable environment for monitoring incidence, and has patient Information coming from death certificates is been using an integrated and homogeneous system of can- routinely added to the morbidity file. Cases known only cer registration throughout the period considered. through the death certificate ('Death Certificate Only' cases (DCO)) contribute less than 5% of the average number of new cancer cases registered per year. Material and methods The present series comprises all new malignant tumours (27,008 cancers, i.e., 14,149 in males and 12,859 in females The Vaud Cancer Registry dataset includes information registered from 1978 to 1987 in the resident population of concerning incident cases of malignant neoplasms occur- the Canton. Overall, histological confirmation exceeded Introduction
294 90% of the series, and tumours discovered at autopsy or from death certificates alone accounted for about 6% during the period considered. A total of 26 cancers or groups of cancers were considered and, in order to analyse temporal trends, incidence rates were separated into two five-year periods, from 1978 to 1982 and from 1983 to 1987. Age-standardized rates, using the direct method on the basis of the World standard population have been chosen for presentation. Although age-standardized rates provide only summary information and may obscure heterogeneous or diverging age-specific patterns, they have been used to provide a single overall statistic, and also because of the greater problem of random variation of age-specific and hence cohort-specific rates. Age-specific rates are vailable on request from FL.
Results and comments Age-standardized incidence rates for major cancers or groups of cancers in the Swiss Canton of Vaud over the two five-year calendar periods 1978-82 and 1983-87 are presented in Table 1 for males and in Table 2 for females,
together with the corresponding numbers of registered cases and percentage rate of change. A brief description is given below for major cancer sites. Digestive sites. Overall age-standardized incidence rates for cancer of the oral cavity and pharynx were stable in males, but substantial declines were observed for oesophagus (-12.7%) and stomach (-27.6%). While appreciable declines were registered for gastric cancer in females as well (-16.1%), the incidence of oropharyngeal and oesophageal cancers tended to rise in females (respectively, by 6.1% and 8.6%). Since these are alcohol- and tobacco-related sites, this probably reflects the increased use of these substances (particularly tobacco) among subsequent generations of Swiss women [11]. It is more difficult to explain the consistent declines observed in both sexes in intestinal cancer incidence (-8.2% for males, -6.5% for females), or the apparently diverging trends of liver cancer (upward for males, downward for females). The latter may be at least partially due to problems of diagnosis and certification of primary liver cancer since the liver is a common site of secondaries, particularly from the lung, and more accurate certification on hepatocarcinomas on cirrhotic liver is now possible [1, 12].
Table 1. Age-standardized incidence rates*fromselected cancers or groups of cancers in males. Vaud, Switzerland, 1978-87. Site
ICD-9
Percent change
Calendar period 1983-87
1978-82 Rate+/100,000
(Number of cases)
Rate+/100,000
(1983-87/1978-82)
(Number of cases)
Mouth or pharynx Oesophagus Stomach Intestine total Uver Gallbladder Pancreas Larynx Trachea, bronchus & lung Pleura Skin melanoma Skin non-melanoma Prostate Testis Bladder Kidney, other urinary Brain and nerves Thyroid Hodgkin's disease Other lymphomas Multiple myeloma Leukaemias
140-9 150 151 152-4 155 156 157 161
19.5 9.0 15.4 34.8 5.7 2.4 7.8 8.0
(344) (174) (314) (701) (115) (50) (159) (138)
19.8 7.9 11.1 32.0 62 1.8 8.4 7.1
(351) (159.) (245) (720) (129) (40) (178) (130)
+ 13 -12.7 -27.6 - 8.2 + 9.2 -25.0 + 7.4 -12.0
162 163 172 173 185 186 188 189 191-2 193 201 200,202 203 204-8
58.9 0.6 6.1 69.3 35.4 7.7 13.3 6.6 5.3 1.8 3.1 11.4 3.6 8.0
(1113) (13) (102) (1358) (808) (109) (260) (117) (84) (29) (45) (207) (69) (144)
57.2 0.4 9.0 85.0 33.4 83 15.2 8.9 53 1.7 IS 11.7 2.7 7.9
(1129) (8) (167) (1751) (833) (126) (317) (166) (88) (31) (35) (220) (63) (144)
- 2.9 -37.1 +49.0 +22.6 - 5.6 + 7.9 +143 +33.6 + 1.1 - 2.9 -19.8 + 2.7 -23.6 - 0.8
Total, all sites
140-208
350.4
(6761)
362.9
(7388)
+ 3.6
All sites but skin non-melanoma
Tot(-173)
281.1
(5403)
277.9
(5637)
- 1.1
+
On the world standard population.
295 Table 2. Age-standardized incidence rates"1"fromselected cancers or groups of cancers in females. Vaud, Switzerland, 1978-87. Site
ICD-9 1978-82 Rate+/100,000
Mouth or pharynx Oesophagus Stomach Intestine total Liver Gallbladder Pancreas Larynx Trachea, bronchus & lung Pleura Skin melanoma Skin non-melanoma Breast Cervix uteri Corpus uteri Ovary Bladder Kidney, other urinary Brain and nerves Thyroid Hodgkin's disease Other lymphomas Multiple myeloma Leukaemias
162 163 172 173 174 180 182 183 188 189 191-2 193 201 200,202 203 204-8
44.4 64.3 9.8 12.7 8.9 2.4 3.6 4.1 4.0 1.7
Total, all sites All sites but skin non- melanoma +
140-9 150 151 152-4 155 156 157 161
Percent change
Calendar period
(1983-87/1978-82)
1983-87
(Number of cases)
Rate+/100,000
(Number of cases)
3.6 2.2 5.1 24.6 1.4 3.5 4.8 0.5
(86) (66) (173) (724) (40) (110) (141) (12)
3.8 2.4 43 23.0 0.9 2.6 5.6 0.8
(93) (63) (153) (736) (30) (93) (176) (16)
+ 6.1 + 8.6 -16.1 - 6.5 -34.9 -26.4 +17.5 +45.9
6.8
1.7 6.0
(172) (7) (161) (1139) (1415) (198) (299) (202) (74) (81) (63) (81) (29) (161) (49) (135)
95 92 602 69.5 83 12.0 10.2 2.9 4.2 3.9 4.3 2.2 6.5 1.9 5.6
(235) (-) (199) (1660) (1621) (186) (284) (247) (101) (108) (70) (83) (37) (164) (52) (127)
+39.7 +20.7 +35.6 + 8.0 -15.3 - 5.9 +14.5 +20.7 +14.4 - 43 + 6.9 +31.0 -0.5 + 8.2 - 7.0
140-208
244.4
(5993)
265.6
(6866)
+ 8.7
Tot(-173)
200.1
(4854)
205.4
(5206)
+ 2.7
0.3 7.7
6.6
On the world standard population.
An approximately 25% fall was observed for both sexes in gallbladder cancer incidence, which is probably at least partially attributable to increased cholecystectomy rates [13] (although some role for a decreased prevalence of the best-known risk factor for the disease, obesity [14], cannot be ruled out). By contrast, the trend in pancreatic cancer rates was upward in both sexes, though to a greater extent in females (i.e., +17% vs +7% in males). Respiratory tract. The pattern of cancer of the larynx was similar to that observed for oral cavity and oesophagus, with some fall in males (-12.0%) but a rise (though based on small absolute numbers) in females (from 12 to 16 registered cases). The common aetiology of these neoplasms was thus confirmed [1]. More important, in terms of absolute numbers and hence public health implications, was the diverging pattern for lung cancer, whose incidence was stable (or slightly declining, i.e., by -2.9%) in males, but apparently upward (+39.7%) in females, in clear reflection of the different trends in smoking prevalence in subsequent generations of Swiss males and females [11]. In this population, when non-melanomatous skin cancers are excluded,
lung cancer is now the fifth leading cause of cancer incidence in females, after breast, intestine, endometrium and ovary. Consequently, over the five-year calendar periods considered, overall incidence from all respiratory tract neoplasms decreased by 4.8% in males, but increased by 32.5% in females, and the corresponding sex ratio declined from 8.7 to 6.2 (and to 6.0 when only lung cancer is considered). Skin. Both melanoma and non-melanomatous skin cancer increased appreciably in the two sexes, although the proportional rise was apparently greater for melanoma in males (+49.0% vs 20.7% in females) and in non-melanomatous cancers in females (+35.6% vs 22.6% in males). The increase in registered incidence was greater for melanoma in males than for any other cancer site. It is possible that these rises are influenced by improved notification and earlier diagnosis of skin neoplasms, but their extent indicates that these upward trends are at least in part real and probably substantial, and should be attributed, as in other populations, to the changed patterns of exposure to sunlight and
296 ready had one of the highest melanoma incidence rates in Europe [16]. Breast and female genital tract. Breast cancer incidence rates increased by 8%, from 64.3 to 69.5/100,000 women. As in the case of skin melanoma, the importance of these rises should be viewed in relation to the already high rates, on a Europea scale, of the early 1980s [16]. However, no simple explanation, in terms of either risk factor exposure or changed instruments or criteria for diagnosis or notification is available. There were appreciable declines in the incidence not only of invasive cervical cancer (-15.3%) but also of cancer of the endometrium (—5.9%), which should be related to hysterectomy rates and possibly to a changed prevalence of obesity, as in the case of gallbladder cancer [14]. Ovarian cancer incidence, in contrast, increased by 14.5%. Thus, the overall incidence of all female genital tract cancers changed only slightly (-4.1%). Male genital tract. Cancer of the prostate was the second leading site (excluding non-melanoma skin cancer) in males, but this incidence declined by over 5% over the quinquennia considered, from 35.4 to 33.4/100,000. In contrast, a modest rise (+7.9%, from 7.7 to 8.3/100,000) was observed for testicular cancer, although rates in the Canton of Vaud were already among the highest in Europe in the early 1980s [16]. Larger rises in testicular cancer incidence have been observed in most industrialized countries [17—19], but the reason for this is unknown. Urinary tract. The incidence of cancer of the kidney and bladder rose by 10% to 20% in both sexes, the apparently greater increase for kidney in males (+34%) and for bladder in females (+21%) being easily explainable in terms of random variation. Since these are two of the tobacco-related sites [20], trends in females are consistent with the general pattern in this group of neoplasms, but it is more difficult to explain male trends, if not in terms of a more accurate distinction between papillomas and carcinomas. Brain. Brain cancer incidence was stable in both sexes. This is at variance with the upward trends observed in several other incidence registration areas [21, 22] (but not in Rochester, Minnesota), where specific attention is accorded to uniform long-term surveillance of brain neoplasms [23]. The steady rates observed in these two well-monitored populations cast doubt on the earlier observations of a general upward trend in brain cancer rates. Thyroid. This is another site showing high incidence and mortality rates in Switzerland, although mortality has been steadily downward over the last decades [16, 24]. Incidence rates, by contrast, have tended to be stable, or to have a slightly upward trend in both sexes, in probable confirmation of the changes in diagnostic criteria and histopathologic patterns of the disease [25,26]. Lymphomas and leukaemias. The overall pattern for all
neoplasms of the reticulc-endothelial system has been largely stable, with consistent rates for non-Hodgkin's lymphomas, and some apparent inconsistency across the sexes for Hodgkin's disease. This, however, can easily be explained in terms of random variation. Of particular importance is the absence of an upward trend for multiple myeloma, since this is one of the neoplasms for which generalized rises in incidence have been observed (although probably largely or totally attributable to improved diagnosis) [27, 28]. Likewise, no increase was observed for leukaemia incidence, and, if anything, some decline has been apparent among females. Total cancer incidence. Overall age-standardized incidence for all sites was upward for both sexes (+3.6% in males, from 350.4 to 362.9/100,000; +8.7% in females, from 244.4 to 265.6/100,000). When non-melanomatous skin cancer was excluded, however, a moderate decline (-1.1%) was apparent in males, whereas the rise in females, although still present, was substantially reduced (+2.7%). Rates for the 5-year period 1983-87 were 277.9 and 205.4 in males and females, respectively, and the overall sex ratio remained stable at around 1.4 between the two five-year calendar periods considered.
Discussion A major problem in the interpretation of trends in cancer incidence pertains to the reliability and comparability of data collected in subsequent calendar periods. Some sites, including prostate, brain and multiple myeloma, are known to be particularly affected by this problem [1]. The absence of any material trends in incidence for these neoplasms in the present dataset is therefore of substantial methodological importance, since it provides some (albeit indirect) indication of a uniform, high-standard incidence monitoring system. This observation, therefore, lends greater credibility to the other trends observed, particularly to the generalized rises in all tobacco-related sites in females (while corresponding male rates were stable or slightly decreasing), and the increases in female breast and skin cancer (most notably skin melanomas) in both sexes. In a prevention and public health perspective, it is certainly discouraging to note that most of the rises were restricted to cancer sites whose aetiology has long been well defined, i.e., tobacco for females, and sunshine or other sources of non-ionising radiation, although, again in a public health perspective, it is certainly reassuring to be able to document in terms of incidence rates the levelling of the tobacco-related cancer epidemic in males. Ironically, some of the largest declines were observed for neoplasms whose aetiology is still largely undefined. This includes not only the persisting fall in gastric cancer [29] (although the rate of fall seems now reduced in females, suggesting a possible asymptote [30]), but also the appreciable declines in intestinal cancer incidence, and the slight
297 declines in prostatic cancer. Thus, inspection of recent changes in cancer incidence in the Vaud population provides easily followed clues to effective intervention in some of the current upward trends in cancer incidence, particularly those of tobacco-related cancers in females, and of skin neoplasms.
Acknowledgements The contribution of the Aargau, St-Gall and Swiss Leagues against Cancer, Bern, is gratefully acknowledged.
References 1. Doll R, Peto R. The causes of cancer. Quantitative estimates of avoidable risks of cancer in the United States today. JNCI 1981; 66: 1191-308. 2. Campbell H, Chiang R, Hansluwka H. Cancer mortality in Europe. Patterns and trends -1955 to 1974. World Health Stat Quart 1980; 33: 152-84. 3. Campbell H. Cancer mortality in Europe. Site-specific patterns and trends 1955 to 1974. World Health Stat Quart 1980; 33: 241-80. 4. Cairns J, Boyle P. Cancer chemotherapy (Letter). Science 1983; 220: 252-3. 5. Bailar JC III, Smith EM. Progress against cancer? N Engl J Med 1986; 314: 1226-32. 6. Hakulinen T, Andersen AA, Molker B et al. Trends in cancer incidence in the Nordic countries. Acta Pathol Microbiol Immunol Scan (A) 1986; 94: 25-37. 7. Boyle P. Relative value of incidence and mortality data in cancer research. In: Boyle P, Muir CS, Grundmann E (eds). Cancer mapping. Recent Results in Cancer Research. Berlin: Springer Verlag, 1989; 114:41-63. 8. Levi F, La Vecchia C, Te VC et al. Descriptive epidemiology of skin cancer in the Swiss canton of Vaud. Int J Cancer 1988; 42: 811-6. 9. Levi F, La Vecchia C. Trends in brain cancer incidence (Letter). Lancet 1989; ii: 917. 10. Levi F. Statistics from the registry of the canton of Vaud, Switzerland, 1978-1982. In: Muir CS, Waterhouse J, Mack T et al. (eds). Cancer Incidence in Five Continents, vol V. Lyon, International Agency for Research on Cancer 1987, pp 634-9. (IARC Scientific Publication no 88). 11. La Vecchia C, Levi F, Decarii A et al. Trends in smoking and lung cancer in Switzerland. Prev Med 1988; 17: 712-24. 12. Hill C, Benhamou E, Doyon F, Flamant R. Evolution de la mortal it* par cancer en France entre 1950 et 1985. Collection 'Statistiques de sanul'. INSERM, Paris, 1989; pp 100-21.
13. Strom BL, Hibberd PL, Soper KA et al. International variations in epidemiology of cancers of the extrahepatic binary tract Cancer Res 1985:45:5165-8. 14. Lew EA, Garfinkel L. Variations in mortality by weight among 750,000 men and women. J Chronic Dis 1979; 32: 565-6. 15. Lee JAH. Melannm? an ' e.oosure to sunlight. Epidemiol Rev 1982; 4:110-36. 16. Levi F, Maisonneuve P, Filiberti R et at Cancer incidence and mortality in Europe. Soz Praeventivmed 1989; 34 (suppl 2): S1-S84. 17. Davies JM. Testicular cancer in England and Wales. Some epidemiological aspects. Lancet 1981; i: 928. 18. Morris Brown L, Pottern LM, Hoover RN et al. Testicular cancer in the United States: Trends in incidence and mortality. Int J Epidemiol 1986; 15: 164-70. 19. Osterlind A. Diverging trends in incidence and mortality of testicular cancer in Denmark, 1943-1982. Br J Cancer 1986; 53: 501-5. 20. US Office on Smoking and Health. The health consequences of smoking; Cancer. A report of the Surgeon General of the Public Health Service. US GPO, Washington 1982. 21. Ahlbom A, Rodvall Y. Brain tumour trends (Letter). Lancet 1989; ii: 1272. 22. Ben-Shlomo Y, Smith GD. Brain tumour trends (Letter). Lancet 1989; ii: 1272-3. 23. Annegers JF, Schoenberg BS, Okazaki H et al. Epidemiologic study of primary intracranial neoplasms. Arch Neurol 1981; 38: 217-9. 24. Levi F, Decarii A, La Vecchia C Trends in cancer mortality in Switzerland, 1951-1984. Rev Epidemiol et Same" Publ 1988; 36: 15-25. 25. Weiss W. Changing incidence of thyroid cancer. JNCI 1979; 62: 1137—42. 26. Pottem ML, Stone BJ, Day NE et al. Thyroid cancer in Connecticut, 1935-1975: An analysis by cell type. Am J Epidemiol 1980; 112: 764-74. 27. Cuzick J, Velez R, Doll R. International variations and temporal trends in mortality from multiple myeloma. Int J Cancer 1983; 32: 13-9. 28. Turesson I, Zettervall O, Cuzick J et al. Comparison of trends in the incidence of multiple myeloma in MalmS, Sweden, and other countries, 1950-1979. N Engl J Med 1984; 310: 421-4. 29. Howson CP, Hiyama T, Wynder EL. The decline in gastric cancer Epidemiology of an unplanned triumph. Epidemiol Rev 1986; 8: 1-27. 30. Levi F, Decarii A, La Vecchia C, Randriamiharisoa A. Cancer mortality in Switzerland, 1951-1984: Effects of age, birth cohort and period of death. Schweiz med Wschr 1988; 118 (Suppl 26): pp 28-9. Received 10 January 1990; accepted 28 February 1990. Correspondence to: Dr. Fabio Levi Registre Vaudois des Tumeurs CHUV BH-06 1011 Lausanne, Switzerland
Original article Changes in cancer incidence in the Swiss canton of Vaud, 1978-87 F. Levi,L2 V.C. Te1 & C. La Vecchia2-3 l
Registre Vaudois des Tumeurs, CHUV BH-06, Lausanne, Switzerland; 2Inslitut universitaire de midecine sociale et preventive, Lausanne, Switzerland; ^Istituto di Ricerche Farmacologiche 'Mario Negri', Milan, Italy
Summary. Changes in age-standardized cancer registration rates in the Swiss Canton of Vaud (population 530,000) over the two five-year calendar periods 1978-82 and 1983-87 were analyzed. The incidence of occurrence at lung and other tobacco-related sites remained stable (or slightly decreased in males), but showed a substantial increase in females (approximately 40%, from 6.8 to 9.5/100,000 world standard, for lung alone). Other upward trends were observed for skin in both sexes (approaching 50% for melanoma in males), female breast (+8.0%, reaching 69.5/100,000), ovary and urinary tract neoplasms. In contrast, declines were observed not only for stomach and cervix, but also for intestine, gallbladder and endometrium. Consequently, overall total cancer incidence (excluding non-melanomatous skin) declined by 1.1% in males, but increased by 2.7% in females, reaching values of 277.9 and 205.4/100,000, respectively, in 1983-87. The absence of any substantive trends in incidence for cancers of the prostate, testis, brain and multiple myeloma is of potential interest, and represents an important indicator of the uniformly high standard of monitoring by this cancer registration scheme. In a public health perspective, it is discouraging that most of the increases were restricted to cancer sites whose etiology has long been well defined, i.e., tobacco for females and sunshine or other sources of non-ionising radiation, although it is reassuring to be able to document the levelling of tobacco-related cancer incidence in males. Key words: descriptive epidemiology, cancer incidence, cancer registration, time trends
ring in the resident population of the Canton (about 530,000 inhabitants in 1980) [10]. It began operation in Trends in cancer rates have usually been studied in relation January 1972, and the registration scheme was to mortality data, because mortality statistics have been progressively implemented during the first few years folavailable longer than incidence statistics, and are also more lowing its inception. reliable in various aspects and situations, as they are less The registry is tumour-based and multiple primaries ocaffected by improvements in detection, diagnosis and cer- curring in the same person are entered separately. However, tification [1-5]. Cancer registration data, on the other hand, multiple non-melanomatous skin tumours are classified by have major advantages in terms of a standardized quality of site of first recognized tumour of the same morphological information and a high rate of histo-pathological confirma- type. Notification is based on a voluntary agreement tion. Moreover, their trends over time are not influenced by between the recording medical institutions of the Canton changes in treatment nor, therefore, survival rates [6]. Thus, and the Registry. incidence data can, in principle, offer important informaThe main information available from the register comtion [7], although their value and contribution to analysis of prises socio-demographic characteristics of the patient (i.e., trends in cancer rates are still under discussion [1, 6]. age, sex), primary site and histological type of the tumour As a specific contribution to this debate, in this article according to the standard International Classification of we discuss changes in incidence rates from the Cancer Diseases for Oncology (ICD-O) and time of confirmation. Registry of the Swiss Canton of Vaud between 1978 and Passive and active follow-up information is recorded and 1987. For several complex situations and cancer sites (e.g., each subsequent item of information concerning an already skin, or brain [8, 9]) this Registry operates in a particularly registered case is used to complete the record of that favourable environment for monitoring incidence, and has patient Information coming from death certificates is been using an integrated and homogeneous system of can- routinely added to the morbidity file. Cases known only cer registration throughout the period considered. through the death certificate ('Death Certificate Only' cases (DCO)) contribute less than 5% of the average number of new cancer cases registered per year. Material and methods The present series comprises all new malignant tumours (27,008 cancers, i.e., 14,149 in males and 12,859 in females The Vaud Cancer Registry dataset includes information registered from 1978 to 1987 in the resident population of concerning incident cases of malignant neoplasms occur- the Canton. Overall, histological confirmation exceeded Introduction
294 90% of the series, and tumours discovered at autopsy or from death certificates alone accounted for about 6% during the period considered. A total of 26 cancers or groups of cancers were considered and, in order to analyse temporal trends, incidence rates were separated into two five-year periods, from 1978 to 1982 and from 1983 to 1987. Age-standardized rates, using the direct method on the basis of the World standard population have been chosen for presentation. Although age-standardized rates provide only summary information and may obscure heterogeneous or diverging age-specific patterns, they have been used to provide a single overall statistic, and also because of the greater problem of random variation of age-specific and hence cohort-specific rates. Age-specific rates are vailable on request from FL.
Results and comments Age-standardized incidence rates for major cancers or groups of cancers in the Swiss Canton of Vaud over the two five-year calendar periods 1978-82 and 1983-87 are presented in Table 1 for males and in Table 2 for females,
together with the corresponding numbers of registered cases and percentage rate of change. A brief description is given below for major cancer sites. Digestive sites. Overall age-standardized incidence rates for cancer of the oral cavity and pharynx were stable in males, but substantial declines were observed for oesophagus (-12.7%) and stomach (-27.6%). While appreciable declines were registered for gastric cancer in females as well (-16.1%), the incidence of oropharyngeal and oesophageal cancers tended to rise in females (respectively, by 6.1% and 8.6%). Since these are alcohol- and tobacco-related sites, this probably reflects the increased use of these substances (particularly tobacco) among subsequent generations of Swiss women [11]. It is more difficult to explain the consistent declines observed in both sexes in intestinal cancer incidence (-8.2% for males, -6.5% for females), or the apparently diverging trends of liver cancer (upward for males, downward for females). The latter may be at least partially due to problems of diagnosis and certification of primary liver cancer since the liver is a common site of secondaries, particularly from the lung, and more accurate certification on hepatocarcinomas on cirrhotic liver is now possible [1, 12].
Table 1. Age-standardized incidence rates*fromselected cancers or groups of cancers in males. Vaud, Switzerland, 1978-87. Site
ICD-9
Percent change
Calendar period 1983-87
1978-82 Rate+/100,000
(Number of cases)
Rate+/100,000
(1983-87/1978-82)
(Number of cases)
Mouth or pharynx Oesophagus Stomach Intestine total Uver Gallbladder Pancreas Larynx Trachea, bronchus & lung Pleura Skin melanoma Skin non-melanoma Prostate Testis Bladder Kidney, other urinary Brain and nerves Thyroid Hodgkin's disease Other lymphomas Multiple myeloma Leukaemias
140-9 150 151 152-4 155 156 157 161
19.5 9.0 15.4 34.8 5.7 2.4 7.8 8.0
(344) (174) (314) (701) (115) (50) (159) (138)
19.8 7.9 11.1 32.0 62 1.8 8.4 7.1
(351) (159.) (245) (720) (129) (40) (178) (130)
+ 13 -12.7 -27.6 - 8.2 + 9.2 -25.0 + 7.4 -12.0
162 163 172 173 185 186 188 189 191-2 193 201 200,202 203 204-8
58.9 0.6 6.1 69.3 35.4 7.7 13.3 6.6 5.3 1.8 3.1 11.4 3.6 8.0
(1113) (13) (102) (1358) (808) (109) (260) (117) (84) (29) (45) (207) (69) (144)
57.2 0.4 9.0 85.0 33.4 83 15.2 8.9 53 1.7 IS 11.7 2.7 7.9
(1129) (8) (167) (1751) (833) (126) (317) (166) (88) (31) (35) (220) (63) (144)
- 2.9 -37.1 +49.0 +22.6 - 5.6 + 7.9 +143 +33.6 + 1.1 - 2.9 -19.8 + 2.7 -23.6 - 0.8
Total, all sites
140-208
350.4
(6761)
362.9
(7388)
+ 3.6
All sites but skin non-melanoma
Tot(-173)
281.1
(5403)
277.9
(5637)
- 1.1
+
On the world standard population.
295 Table 2. Age-standardized incidence rates"1"fromselected cancers or groups of cancers in females. Vaud, Switzerland, 1978-87. Site
ICD-9 1978-82 Rate+/100,000
Mouth or pharynx Oesophagus Stomach Intestine total Liver Gallbladder Pancreas Larynx Trachea, bronchus & lung Pleura Skin melanoma Skin non-melanoma Breast Cervix uteri Corpus uteri Ovary Bladder Kidney, other urinary Brain and nerves Thyroid Hodgkin's disease Other lymphomas Multiple myeloma Leukaemias
162 163 172 173 174 180 182 183 188 189 191-2 193 201 200,202 203 204-8
44.4 64.3 9.8 12.7 8.9 2.4 3.6 4.1 4.0 1.7
Total, all sites All sites but skin non- melanoma +
140-9 150 151 152-4 155 156 157 161
Percent change
Calendar period
(1983-87/1978-82)
1983-87
(Number of cases)
Rate+/100,000
(Number of cases)
3.6 2.2 5.1 24.6 1.4 3.5 4.8 0.5
(86) (66) (173) (724) (40) (110) (141) (12)
3.8 2.4 43 23.0 0.9 2.6 5.6 0.8
(93) (63) (153) (736) (30) (93) (176) (16)
+ 6.1 + 8.6 -16.1 - 6.5 -34.9 -26.4 +17.5 +45.9
6.8
1.7 6.0
(172) (7) (161) (1139) (1415) (198) (299) (202) (74) (81) (63) (81) (29) (161) (49) (135)
95 92 602 69.5 83 12.0 10.2 2.9 4.2 3.9 4.3 2.2 6.5 1.9 5.6
(235) (-) (199) (1660) (1621) (186) (284) (247) (101) (108) (70) (83) (37) (164) (52) (127)
+39.7 +20.7 +35.6 + 8.0 -15.3 - 5.9 +14.5 +20.7 +14.4 - 43 + 6.9 +31.0 -0.5 + 8.2 - 7.0
140-208
244.4
(5993)
265.6
(6866)
+ 8.7
Tot(-173)
200.1
(4854)
205.4
(5206)
+ 2.7
0.3 7.7
6.6
On the world standard population.
An approximately 25% fall was observed for both sexes in gallbladder cancer incidence, which is probably at least partially attributable to increased cholecystectomy rates [13] (although some role for a decreased prevalence of the best-known risk factor for the disease, obesity [14], cannot be ruled out). By contrast, the trend in pancreatic cancer rates was upward in both sexes, though to a greater extent in females (i.e., +17% vs +7% in males). Respiratory tract. The pattern of cancer of the larynx was similar to that observed for oral cavity and oesophagus, with some fall in males (-12.0%) but a rise (though based on small absolute numbers) in females (from 12 to 16 registered cases). The common aetiology of these neoplasms was thus confirmed [1]. More important, in terms of absolute numbers and hence public health implications, was the diverging pattern for lung cancer, whose incidence was stable (or slightly declining, i.e., by -2.9%) in males, but apparently upward (+39.7%) in females, in clear reflection of the different trends in smoking prevalence in subsequent generations of Swiss males and females [11]. In this population, when non-melanomatous skin cancers are excluded,
lung cancer is now the fifth leading cause of cancer incidence in females, after breast, intestine, endometrium and ovary. Consequently, over the five-year calendar periods considered, overall incidence from all respiratory tract neoplasms decreased by 4.8% in males, but increased by 32.5% in females, and the corresponding sex ratio declined from 8.7 to 6.2 (and to 6.0 when only lung cancer is considered). Skin. Both melanoma and non-melanomatous skin cancer increased appreciably in the two sexes, although the proportional rise was apparently greater for melanoma in males (+49.0% vs 20.7% in females) and in non-melanomatous cancers in females (+35.6% vs 22.6% in males). The increase in registered incidence was greater for melanoma in males than for any other cancer site. It is possible that these rises are influenced by improved notification and earlier diagnosis of skin neoplasms, but their extent indicates that these upward trends are at least in part real and probably substantial, and should be attributed, as in other populations, to the changed patterns of exposure to sunlight and
296 ready had one of the highest melanoma incidence rates in Europe [16]. Breast and female genital tract. Breast cancer incidence rates increased by 8%, from 64.3 to 69.5/100,000 women. As in the case of skin melanoma, the importance of these rises should be viewed in relation to the already high rates, on a Europea scale, of the early 1980s [16]. However, no simple explanation, in terms of either risk factor exposure or changed instruments or criteria for diagnosis or notification is available. There were appreciable declines in the incidence not only of invasive cervical cancer (-15.3%) but also of cancer of the endometrium (—5.9%), which should be related to hysterectomy rates and possibly to a changed prevalence of obesity, as in the case of gallbladder cancer [14]. Ovarian cancer incidence, in contrast, increased by 14.5%. Thus, the overall incidence of all female genital tract cancers changed only slightly (-4.1%). Male genital tract. Cancer of the prostate was the second leading site (excluding non-melanoma skin cancer) in males, but this incidence declined by over 5% over the quinquennia considered, from 35.4 to 33.4/100,000. In contrast, a modest rise (+7.9%, from 7.7 to 8.3/100,000) was observed for testicular cancer, although rates in the Canton of Vaud were already among the highest in Europe in the early 1980s [16]. Larger rises in testicular cancer incidence have been observed in most industrialized countries [17—19], but the reason for this is unknown. Urinary tract. The incidence of cancer of the kidney and bladder rose by 10% to 20% in both sexes, the apparently greater increase for kidney in males (+34%) and for bladder in females (+21%) being easily explainable in terms of random variation. Since these are two of the tobacco-related sites [20], trends in females are consistent with the general pattern in this group of neoplasms, but it is more difficult to explain male trends, if not in terms of a more accurate distinction between papillomas and carcinomas. Brain. Brain cancer incidence was stable in both sexes. This is at variance with the upward trends observed in several other incidence registration areas [21, 22] (but not in Rochester, Minnesota), where specific attention is accorded to uniform long-term surveillance of brain neoplasms [23]. The steady rates observed in these two well-monitored populations cast doubt on the earlier observations of a general upward trend in brain cancer rates. Thyroid. This is another site showing high incidence and mortality rates in Switzerland, although mortality has been steadily downward over the last decades [16, 24]. Incidence rates, by contrast, have tended to be stable, or to have a slightly upward trend in both sexes, in probable confirmation of the changes in diagnostic criteria and histopathologic patterns of the disease [25,26]. Lymphomas and leukaemias. The overall pattern for all
neoplasms of the reticulc-endothelial system has been largely stable, with consistent rates for non-Hodgkin's lymphomas, and some apparent inconsistency across the sexes for Hodgkin's disease. This, however, can easily be explained in terms of random variation. Of particular importance is the absence of an upward trend for multiple myeloma, since this is one of the neoplasms for which generalized rises in incidence have been observed (although probably largely or totally attributable to improved diagnosis) [27, 28]. Likewise, no increase was observed for leukaemia incidence, and, if anything, some decline has been apparent among females. Total cancer incidence. Overall age-standardized incidence for all sites was upward for both sexes (+3.6% in males, from 350.4 to 362.9/100,000; +8.7% in females, from 244.4 to 265.6/100,000). When non-melanomatous skin cancer was excluded, however, a moderate decline (-1.1%) was apparent in males, whereas the rise in females, although still present, was substantially reduced (+2.7%). Rates for the 5-year period 1983-87 were 277.9 and 205.4 in males and females, respectively, and the overall sex ratio remained stable at around 1.4 between the two five-year calendar periods considered.
Discussion A major problem in the interpretation of trends in cancer incidence pertains to the reliability and comparability of data collected in subsequent calendar periods. Some sites, including prostate, brain and multiple myeloma, are known to be particularly affected by this problem [1]. The absence of any material trends in incidence for these neoplasms in the present dataset is therefore of substantial methodological importance, since it provides some (albeit indirect) indication of a uniform, high-standard incidence monitoring system. This observation, therefore, lends greater credibility to the other trends observed, particularly to the generalized rises in all tobacco-related sites in females (while corresponding male rates were stable or slightly decreasing), and the increases in female breast and skin cancer (most notably skin melanomas) in both sexes. In a prevention and public health perspective, it is certainly discouraging to note that most of the rises were restricted to cancer sites whose aetiology has long been well defined, i.e., tobacco for females, and sunshine or other sources of non-ionising radiation, although, again in a public health perspective, it is certainly reassuring to be able to document in terms of incidence rates the levelling of the tobacco-related cancer epidemic in males. Ironically, some of the largest declines were observed for neoplasms whose aetiology is still largely undefined. This includes not only the persisting fall in gastric cancer [29] (although the rate of fall seems now reduced in females, suggesting a possible asymptote [30]), but also the appreciable declines in intestinal cancer incidence, and the slight
297 declines in prostatic cancer. Thus, inspection of recent changes in cancer incidence in the Vaud population provides easily followed clues to effective intervention in some of the current upward trends in cancer incidence, particularly those of tobacco-related cancers in females, and of skin neoplasms.
Acknowledgements The contribution of the Aargau, St-Gall and Swiss Leagues against Cancer, Bern, is gratefully acknowledged.
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