- Email: [email protected]
Thyroid cancer in Belarus after Chernobyl
International Congress Series 1299 (2007) 27 – 31
www.ics-elsevier.com
Thyroid cancer in Belarus after Chernobyl Pavel I. Bespalchuk a , Yuri E. Demidchik a,b,⁎, Eugene P. Demidchik a,b , Zigmund E. Gedrevich b , Alena P. Dubovskaya b , Vladimir A. Saenko c,d , Shunichi Yamashita c,e,f a
c
Belarusian State Medical University, Minsk, Belarus b Thyroid Cancer Center, Minsk, Belarus Department of International Health and Radiation Research, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan d Medical Radiological Research Center RAMS, Obninsk, Russian Federation e Department of Molecular Medicine, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan f Department of Public Health and Environment, WHO Headquarters, Geneva, Switzerland
Abstract. During 20 years after the Chernobyl catastrophe (1986–2005 inclusive) thyroid cancer was diagnosed in more than 12,000 patients of Belarus. The peak incidence in children was observed in 1995 and since 2001 only sporadic cases occur in the age group under 15 years old. In adolescents, the maximum was registered in 2001. By contrast, in the age group of 46 years or over, the current tendency is a marked increase in the number of primary thyroid cancers that dictates a correspondent intensification of special kinds of treatment. Despite a great number of patients, disease-associated mortality remains stably low; the increasing incidence indicates that thyroid malignancies have proved an actual medical problem in 5 of the 6 administrative regions of Belarus. © 2006 Elsevier B.V. All rights reserved. Keywords: Thyroid cancer; Incidence; Mortality
1. Introduction Before the Chernobyl Power Plant disaster, thyroid cancer was rarely diagnosed in the Republic of Belarus. Between 1965 and 1993, 1750 cases were cumulatively documented ⁎ Corresponding author. Belarusian State Medical University, 83, Dzerzhinsky av., 220116, Minsk, Belarus. Tel.: +375 172 902971; fax: +375 172 966571. E-mail address: [email protected] (Yu.E. Demidchik). 0531-5131/ © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2006.09.006
28
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
Fig. 1. Crude incidence of thyroid cancer in Belarus before the Chernobyl disaster (1965–1983).
and the crude incidence never exceeded 1.4 per 100,000 (Fig. 1). During that period the majority of patients underwent therapy for an advanced disease, and aggressive pathological types (medullary or anaplastic) occurred much more frequently than nowadays. More than one third of the patients had follicular carcinomas. The peak incidence in females and males was observed in the individuals aged 60–69 and 50–59 years, respectively. On the whole survival rate was rather low. After the Chernobyl accident almost the entire population of the Republic of Belarus was exposed to I-131 fallout. This isotope was incorporated in the thyroid gland and caused an internal irradiation in the vast majority of citizens of Belarus among whom children and adolescents received maximal doses. The aim of this study was to analyze the number of thyroid cancer cases and evaluate the trends in incidence and mortality within the 20-year period after the Chernobyl disaster. 2. Material and methods Data for the analysis were retrieved from the Database of Thyroid Cancer Center (Minsk, Belarus). 3. Results and discussion During the 20 years after the Chernobyl catastrophe (1986–2005 inclusive) thyroid cancer was diagnosed in more than 12,000 patients. The number of individuals in the Belarusian population subjected to special kinds of treatment for thyroid cancer is permanently increasing. These patients need to be followed up; they receive a life-long thyroxin therapy, undergo medical rehabilitation, frequent control of hormonal status, nuclear medicine investigations and radioiodine therapy. Due to these efforts the mortality rate is stable and very low; however, during a rather short period of time thyroid cancer has become a serious medical and social problem whose importance continues to grow (Table 1, Fig. 2). The significant increase of incidence rate in exposed children and adolescents has been reported since 1990 [1] and its association with absorbed thyroid doses was
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
29
Table 1 Number of primary patients, who were living in Belarus at the time of the Chernobyl accident, diagnosed for thyroid carcinoma during January 1, 1986 to June 30, 2006 Region of Belarus
Children
Adolescents
Adults
Total
Brest Vitebsk Gomel Grodno Minsk Mogilev Minsk city Belarus Foreign countries
166 13 382 48 45 45 67 766 6
128 19 234 21 33 31 41 507 3
1523 1601 2377 638 1417 1783 2383 11,722 274
1817 1633 2993 707 1495 1859 2491 12,995 283
Total
772
510
11,996
13,278
officially recognized at a WHO convention in 1995. For those exposed at the age of 19 and older a sharp rise of thyroid cancer incidence was noted in 1992. The incidence of Chernobyl thyroid cancer significantly correlates with the radiation dose. The highest indices were registered in the patients whose thyroid dose exceeded 1 Gy as was demonstrated in two recent publications based on the results of observations in the Ukraine and Belarus [2,3]. The peak of incidence in children was documented in 1995 and since 2001 only sporadic cases occur in the age group under 15 years. In adolescents such a maximum was reached in 2001. However, the current tendency is a profound increase in the number of primary thyroid cancer cases in the age group of 46 years or over (Fig. 3). Characterizing the peculiarities of thyroid cancer in Belarus one should acknowledge (i) the existence of two etiological forms of the disease-sporadic and radiogenic; (ii) a high incidence in children during the first 10 years after the catastrophe; and (iii) the absolute prevalence of the papillary carcinoma.
Fig. 2. Crude incidence of thyroid cancer and disease-associated mortality after the Chernobyl accident (1986–2005).
30
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
Fig. 3. Annual number of cases of thyroid carcinomas in different age groups (1985–2004).
With regard to radiation-induced thyroid cancer, three major factors are indicative of its radiogenic nature. The first is the high prevalence of the disease; before the Chernobyl accident incidence of sporadic thyroid cancer was very low both in children and in adults. The second factor is geographical: the majority of children and adolescents diagnosed for thyroid carcinoma lived in the southern areas of the country located close to the place of catastrophe. The third factor is the detected “dose–effect” correlation. The most dramatic problem has been the increase of thyroid cancer incidence in the age group from 0 to 14 years. The youngest patient diagnosed for thyroid carcinoma was 4.2 years old. It is worth noting that during 4 years after the accident no signs of incidence to grow were noted. According to the literature, in particular to the publication by the International Agency for Research on Cancer (IARC) of WHO and International Association of Cancer Registries, 1998, thyroid cancer in children occurs casuistically rare in most countries around the world (except for the Republic of Belarus). All in all, 920 cases of this malignancy have been documented during the period of 25 years and in some countries of 35 years [4]. By 2000, a commensurable number of cases have been revealed in
Fig. 4. Crude incidence of thyroid cancer in Belarus by region and year (1986–2005).
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
31
Belarus. The majority of patients were from the Gomel region and the south-eastern parts of the Brest region. The distinctive features of thyroid cancer in young adults aged 19–35 years are a very low mortality rate and a strong association with the geographical factor. A low mortality rate is also characteristic for patients aged 36–45 years. However, in these individuals mortality rate is higher in the regions with a high population density and the role of geographical factor is not pronounced. In the age group of 46 years or over, a high mortality rate is noted. It can be explained in part by a relatively high prevalence of the aggressive forms of disease, anaplastic and medullary carcinomas, as compared with those in children, adolescents and young adults. As a whole, current trends in standardized incidence demonstrate that at present the problem of thyroid cancer has proved to be important in 5 of the 6 administrative regions of the Republic of Belarus (Fig. 4). References [1] V. Kazakov, E. Demidchik, L. Astakova, Thyroid cancer after Chernobyl, Nature 359 (1992) 21–22. [2] P. Jacob, T.I. Bogdanova, E. Buglova, et al., Thyroid cancer risk in areas of Ukraine and Belarus affected by the Chernobyl accident, Radiat. Res. 1965 (2006) 1–8. [3] P. Jacob, T.I. Bogdanova, E. Buglova, et al., Thyroid cancer among Ukrainians and Belarusians who were children or adolescents at the time of the Chernobyl accident, J. Radiol. Prot. 26 (2006) 51–67. [4] D.M. Parkin, E. Kramarova, G.J. Draper, et al., (Eds.), International Incidence of Childhood Cancer, Vol. II, IARC Scientific Publication No. 144, International Agency for Research on Cancer, Lyon, 1998.
www.ics-elsevier.com
Thyroid cancer in Belarus after Chernobyl Pavel I. Bespalchuk a , Yuri E. Demidchik a,b,⁎, Eugene P. Demidchik a,b , Zigmund E. Gedrevich b , Alena P. Dubovskaya b , Vladimir A. Saenko c,d , Shunichi Yamashita c,e,f a
c
Belarusian State Medical University, Minsk, Belarus b Thyroid Cancer Center, Minsk, Belarus Department of International Health and Radiation Research, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan d Medical Radiological Research Center RAMS, Obninsk, Russian Federation e Department of Molecular Medicine, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan f Department of Public Health and Environment, WHO Headquarters, Geneva, Switzerland
Abstract. During 20 years after the Chernobyl catastrophe (1986–2005 inclusive) thyroid cancer was diagnosed in more than 12,000 patients of Belarus. The peak incidence in children was observed in 1995 and since 2001 only sporadic cases occur in the age group under 15 years old. In adolescents, the maximum was registered in 2001. By contrast, in the age group of 46 years or over, the current tendency is a marked increase in the number of primary thyroid cancers that dictates a correspondent intensification of special kinds of treatment. Despite a great number of patients, disease-associated mortality remains stably low; the increasing incidence indicates that thyroid malignancies have proved an actual medical problem in 5 of the 6 administrative regions of Belarus. © 2006 Elsevier B.V. All rights reserved. Keywords: Thyroid cancer; Incidence; Mortality
1. Introduction Before the Chernobyl Power Plant disaster, thyroid cancer was rarely diagnosed in the Republic of Belarus. Between 1965 and 1993, 1750 cases were cumulatively documented ⁎ Corresponding author. Belarusian State Medical University, 83, Dzerzhinsky av., 220116, Minsk, Belarus. Tel.: +375 172 902971; fax: +375 172 966571. E-mail address: [email protected] (Yu.E. Demidchik). 0531-5131/ © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.ics.2006.09.006
28
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
Fig. 1. Crude incidence of thyroid cancer in Belarus before the Chernobyl disaster (1965–1983).
and the crude incidence never exceeded 1.4 per 100,000 (Fig. 1). During that period the majority of patients underwent therapy for an advanced disease, and aggressive pathological types (medullary or anaplastic) occurred much more frequently than nowadays. More than one third of the patients had follicular carcinomas. The peak incidence in females and males was observed in the individuals aged 60–69 and 50–59 years, respectively. On the whole survival rate was rather low. After the Chernobyl accident almost the entire population of the Republic of Belarus was exposed to I-131 fallout. This isotope was incorporated in the thyroid gland and caused an internal irradiation in the vast majority of citizens of Belarus among whom children and adolescents received maximal doses. The aim of this study was to analyze the number of thyroid cancer cases and evaluate the trends in incidence and mortality within the 20-year period after the Chernobyl disaster. 2. Material and methods Data for the analysis were retrieved from the Database of Thyroid Cancer Center (Minsk, Belarus). 3. Results and discussion During the 20 years after the Chernobyl catastrophe (1986–2005 inclusive) thyroid cancer was diagnosed in more than 12,000 patients. The number of individuals in the Belarusian population subjected to special kinds of treatment for thyroid cancer is permanently increasing. These patients need to be followed up; they receive a life-long thyroxin therapy, undergo medical rehabilitation, frequent control of hormonal status, nuclear medicine investigations and radioiodine therapy. Due to these efforts the mortality rate is stable and very low; however, during a rather short period of time thyroid cancer has become a serious medical and social problem whose importance continues to grow (Table 1, Fig. 2). The significant increase of incidence rate in exposed children and adolescents has been reported since 1990 [1] and its association with absorbed thyroid doses was
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
29
Table 1 Number of primary patients, who were living in Belarus at the time of the Chernobyl accident, diagnosed for thyroid carcinoma during January 1, 1986 to June 30, 2006 Region of Belarus
Children
Adolescents
Adults
Total
Brest Vitebsk Gomel Grodno Minsk Mogilev Minsk city Belarus Foreign countries
166 13 382 48 45 45 67 766 6
128 19 234 21 33 31 41 507 3
1523 1601 2377 638 1417 1783 2383 11,722 274
1817 1633 2993 707 1495 1859 2491 12,995 283
Total
772
510
11,996
13,278
officially recognized at a WHO convention in 1995. For those exposed at the age of 19 and older a sharp rise of thyroid cancer incidence was noted in 1992. The incidence of Chernobyl thyroid cancer significantly correlates with the radiation dose. The highest indices were registered in the patients whose thyroid dose exceeded 1 Gy as was demonstrated in two recent publications based on the results of observations in the Ukraine and Belarus [2,3]. The peak of incidence in children was documented in 1995 and since 2001 only sporadic cases occur in the age group under 15 years. In adolescents such a maximum was reached in 2001. However, the current tendency is a profound increase in the number of primary thyroid cancer cases in the age group of 46 years or over (Fig. 3). Characterizing the peculiarities of thyroid cancer in Belarus one should acknowledge (i) the existence of two etiological forms of the disease-sporadic and radiogenic; (ii) a high incidence in children during the first 10 years after the catastrophe; and (iii) the absolute prevalence of the papillary carcinoma.
Fig. 2. Crude incidence of thyroid cancer and disease-associated mortality after the Chernobyl accident (1986–2005).
30
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
Fig. 3. Annual number of cases of thyroid carcinomas in different age groups (1985–2004).
With regard to radiation-induced thyroid cancer, three major factors are indicative of its radiogenic nature. The first is the high prevalence of the disease; before the Chernobyl accident incidence of sporadic thyroid cancer was very low both in children and in adults. The second factor is geographical: the majority of children and adolescents diagnosed for thyroid carcinoma lived in the southern areas of the country located close to the place of catastrophe. The third factor is the detected “dose–effect” correlation. The most dramatic problem has been the increase of thyroid cancer incidence in the age group from 0 to 14 years. The youngest patient diagnosed for thyroid carcinoma was 4.2 years old. It is worth noting that during 4 years after the accident no signs of incidence to grow were noted. According to the literature, in particular to the publication by the International Agency for Research on Cancer (IARC) of WHO and International Association of Cancer Registries, 1998, thyroid cancer in children occurs casuistically rare in most countries around the world (except for the Republic of Belarus). All in all, 920 cases of this malignancy have been documented during the period of 25 years and in some countries of 35 years [4]. By 2000, a commensurable number of cases have been revealed in
Fig. 4. Crude incidence of thyroid cancer in Belarus by region and year (1986–2005).
P.I. Bespalchuk et al. / International Congress Series 1299 (2007) 27–31
31
Belarus. The majority of patients were from the Gomel region and the south-eastern parts of the Brest region. The distinctive features of thyroid cancer in young adults aged 19–35 years are a very low mortality rate and a strong association with the geographical factor. A low mortality rate is also characteristic for patients aged 36–45 years. However, in these individuals mortality rate is higher in the regions with a high population density and the role of geographical factor is not pronounced. In the age group of 46 years or over, a high mortality rate is noted. It can be explained in part by a relatively high prevalence of the aggressive forms of disease, anaplastic and medullary carcinomas, as compared with those in children, adolescents and young adults. As a whole, current trends in standardized incidence demonstrate that at present the problem of thyroid cancer has proved to be important in 5 of the 6 administrative regions of the Republic of Belarus (Fig. 4). References [1] V. Kazakov, E. Demidchik, L. Astakova, Thyroid cancer after Chernobyl, Nature 359 (1992) 21–22. [2] P. Jacob, T.I. Bogdanova, E. Buglova, et al., Thyroid cancer risk in areas of Ukraine and Belarus affected by the Chernobyl accident, Radiat. Res. 1965 (2006) 1–8. [3] P. Jacob, T.I. Bogdanova, E. Buglova, et al., Thyroid cancer among Ukrainians and Belarusians who were children or adolescents at the time of the Chernobyl accident, J. Radiol. Prot. 26 (2006) 51–67. [4] D.M. Parkin, E. Kramarova, G.J. Draper, et al., (Eds.), International Incidence of Childhood Cancer, Vol. II, IARC Scientific Publication No. 144, International Agency for Research on Cancer, Lyon, 1998.