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Point of view: Incidental renal carcinoma
POINT OF VIEW
POIN’____ T OF VIEW: INCIDENTAL RENAL CARCINOMA _~ Renal cystic masses are common and malignant tumors relatively uncommon. Up to 30 percent of the population over the age of sixty years will have asymptomatic cysts found on ultrasound examination.’ ’ Renal carcinoma, the most common malignant renal tumor, has age standardized incidence rates of 3.6-5.6 per 100,000 males and 1.7-3.4 per 100.000 females in the United Kingdom. The range of incidence rates illustrates regional variationthere are also marked international variations in incidence, being higher in northern Europe and North America and lower in Africa, Asia, and South America.:’ The majority of renal mass lesions. therefore, do not require treatment but must be accurately diagnosed. This imposes a heavy responsibility on those involved with generating and reporting the investigative images. There are now well-established criteria for distinguishing suspicious from nonsuspicious renal masses, and these must be applied methodically if malignancy is not to be overlooked.” As the aforementioned incidence figures indicate, renal carcinoma affects males more often than females (approximately 2:1), and it can occur at any age. although most common in the sixth and seventh decades. Most clinical series of patients with this tumor contain a proportion discovered by chance, usually during investigation for some unrelated pathology. The proportion depends on the source of data. Careful postmortem studies on hospital inpatients have shown that a significant number of renal tllmors arc not diagnosed during life.” 7 A series of 16,294 autopsies performed in Malmo, Sweden, revealed 350 cases of renal carcinoma, 235 of which lvere not recognized during life. This series even included patients \\rith metastatic disease. It would appear that in clinical series, the proportion of tumors discovered incidentally is increasing. Riches, Criffiths. and Thackray8 reported that 4 percent of 1,746 tumors were an incidental discovcr); and S’kinner and associates” detailed 7 percent of 309 carefully studied patients. In more recent small series. Ueda and Mihara”’ found that 2 of 16 (13%) patients presenting between 1976 and 1980 had their tumor found by chance compared with 13 of 37 (35%) between 1981 and 1985. Similarly, Konnak and Crossman” indicated that 7 of 56 (13%) of their tumors were discovered incidentally during the period 1961 to 1973, compared with 22 of 46 (48%) during the four years to 1980.
The submerged part of the “iceberg” of renal tumor prevalence is thus partly coming to light and most likely reflects the wider use of imaging techniques such as ultrasound, computer-assisted tomography, and nuclear magnetic resonance imaging. Use of ultrasound to localize calculi for extracorporeal lithotrips!; represents a further scenario in which tumors may be detected and 2 sllch cases have recently been reported. I2 Tumors discovered incidentally ha1.v a better prognosis than symptomatic tumors, I ( most likel? owing to their lower stage than tumors producing symptoms. Of 3,232 histologically confirmed cases of renal carcinoma, 77.5 percent of thosle without symptoms had disease confined to the kidney and only 9.4 percent had distant metastase\. Hy comparison, only 43.9 percent of those with :qmptoms had localized disease and 28 percent had distant metastases at presentation.14 Survival after nephrectomy for renal carcinoma is related to the anatomic extent of the disease with the presence or absence of metastases being the most important determinant. Patients with no evidence of metastases have a 90 percent two-year survival compared with 20 percent for those with metastases. Five-year survival rates of up to 93 percent have been reported for tumors confined to the :rcnal capsule.‘” Although there are sensitive diagnostic methods and an effective treatment, the relative rarit!. of this tumor makes screening unlikely to be cost-effective. However, for patients at highest risk (males over age 50) having ultrasound for other reasons, a “quick look” at the kidneys may identify a tlmlor for which there is effective treatment.
Reference\
No 15, 1976. 4. Bosniak MA: The current radiological approach to renal cvsts. Radiologv 158: 1 (1986). 5. ‘Hellsten?, Berge T, and Wehlin L: Unrecognised renal cell carcinoma. Clinical and diagnostic aspects, Stand J Urol 8: 269 (1981). 6. Hellsten S, Berge T, and Wehlin L: Unrecognised renal cell carcinoma. Clinical and pathological aspects, Stand J Urol8: 273 (1981). 7. Hadju SI, and Thomas AG: Renal cell carcinoma at autopsy, J Urol 97: 978 (1967). 8. Riches EW, Griffiths IH, and Thackray AC: New growths of the kidney and ureter, Br J Urol 23: 297 (1951). 9. Skinner DG, et 01: Diagnosis and management of renal cell carcinoma. A clinical and pathological study of 309 cases, Cancer 28: 1165 (1971). 10. IJeda T, and Mihara Y: Incidental detection of renal car-
394
cinema during radiological imaging, Br J Urol 59: 513 (1987). 11. Konnack JW, and Grossman HB: Renal cell carcinoma as an incidental finding, J Urol 34: 1094 (1986). 12. Parr NJ, Ritchie AWS, Moussa SA, and Tolley DA: Incidental renal carcinoma discovered during ultrasound localisation of renal calculi for extracorporeal piezoelectric lithotripsy, Br J Urol 68: 211 (1991). 13. Thomson IM, and Peek M: Improvement in survival of patients with renal cell carcinoma-the role of the serendipitiously detected tumor, J Urol 140: 487 (1988). 14. Ritchie AWS, and deKernion JB: Incidental renal neoplasms: incidence in Los Angeles County, treatment and prognosis, in Schroder FH (Ed): Progress and Controversies in Oncological Urology, New York, Alan Liss Inc., II, 1988, p 347. 15. Selli C, Hinshaw W, Woodward BH, and Paulson DF: Stratification of risk factors in renal cell carcinoma, Cancer 52: 899 (1983).
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/ APRIL 1992
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VOLUME
XxX1X.
NUMBER
4
POIN’____ T OF VIEW: INCIDENTAL RENAL CARCINOMA _~ Renal cystic masses are common and malignant tumors relatively uncommon. Up to 30 percent of the population over the age of sixty years will have asymptomatic cysts found on ultrasound examination.’ ’ Renal carcinoma, the most common malignant renal tumor, has age standardized incidence rates of 3.6-5.6 per 100,000 males and 1.7-3.4 per 100.000 females in the United Kingdom. The range of incidence rates illustrates regional variationthere are also marked international variations in incidence, being higher in northern Europe and North America and lower in Africa, Asia, and South America.:’ The majority of renal mass lesions. therefore, do not require treatment but must be accurately diagnosed. This imposes a heavy responsibility on those involved with generating and reporting the investigative images. There are now well-established criteria for distinguishing suspicious from nonsuspicious renal masses, and these must be applied methodically if malignancy is not to be overlooked.” As the aforementioned incidence figures indicate, renal carcinoma affects males more often than females (approximately 2:1), and it can occur at any age. although most common in the sixth and seventh decades. Most clinical series of patients with this tumor contain a proportion discovered by chance, usually during investigation for some unrelated pathology. The proportion depends on the source of data. Careful postmortem studies on hospital inpatients have shown that a significant number of renal tllmors arc not diagnosed during life.” 7 A series of 16,294 autopsies performed in Malmo, Sweden, revealed 350 cases of renal carcinoma, 235 of which lvere not recognized during life. This series even included patients \\rith metastatic disease. It would appear that in clinical series, the proportion of tumors discovered incidentally is increasing. Riches, Criffiths. and Thackray8 reported that 4 percent of 1,746 tumors were an incidental discovcr); and S’kinner and associates” detailed 7 percent of 309 carefully studied patients. In more recent small series. Ueda and Mihara”’ found that 2 of 16 (13%) patients presenting between 1976 and 1980 had their tumor found by chance compared with 13 of 37 (35%) between 1981 and 1985. Similarly, Konnak and Crossman” indicated that 7 of 56 (13%) of their tumors were discovered incidentally during the period 1961 to 1973, compared with 22 of 46 (48%) during the four years to 1980.
The submerged part of the “iceberg” of renal tumor prevalence is thus partly coming to light and most likely reflects the wider use of imaging techniques such as ultrasound, computer-assisted tomography, and nuclear magnetic resonance imaging. Use of ultrasound to localize calculi for extracorporeal lithotrips!; represents a further scenario in which tumors may be detected and 2 sllch cases have recently been reported. I2 Tumors discovered incidentally ha1.v a better prognosis than symptomatic tumors, I ( most likel? owing to their lower stage than tumors producing symptoms. Of 3,232 histologically confirmed cases of renal carcinoma, 77.5 percent of thosle without symptoms had disease confined to the kidney and only 9.4 percent had distant metastase\. Hy comparison, only 43.9 percent of those with :qmptoms had localized disease and 28 percent had distant metastases at presentation.14 Survival after nephrectomy for renal carcinoma is related to the anatomic extent of the disease with the presence or absence of metastases being the most important determinant. Patients with no evidence of metastases have a 90 percent two-year survival compared with 20 percent for those with metastases. Five-year survival rates of up to 93 percent have been reported for tumors confined to the :rcnal capsule.‘” Although there are sensitive diagnostic methods and an effective treatment, the relative rarit!. of this tumor makes screening unlikely to be cost-effective. However, for patients at highest risk (males over age 50) having ultrasound for other reasons, a “quick look” at the kidneys may identify a tlmlor for which there is effective treatment.
Reference\
No 15, 1976. 4. Bosniak MA: The current radiological approach to renal cvsts. Radiologv 158: 1 (1986). 5. ‘Hellsten?, Berge T, and Wehlin L: Unrecognised renal cell carcinoma. Clinical and diagnostic aspects, Stand J Urol 8: 269 (1981). 6. Hellsten S, Berge T, and Wehlin L: Unrecognised renal cell carcinoma. Clinical and pathological aspects, Stand J Urol8: 273 (1981). 7. Hadju SI, and Thomas AG: Renal cell carcinoma at autopsy, J Urol 97: 978 (1967). 8. Riches EW, Griffiths IH, and Thackray AC: New growths of the kidney and ureter, Br J Urol 23: 297 (1951). 9. Skinner DG, et 01: Diagnosis and management of renal cell carcinoma. A clinical and pathological study of 309 cases, Cancer 28: 1165 (1971). 10. IJeda T, and Mihara Y: Incidental detection of renal car-
394
cinema during radiological imaging, Br J Urol 59: 513 (1987). 11. Konnack JW, and Grossman HB: Renal cell carcinoma as an incidental finding, J Urol 34: 1094 (1986). 12. Parr NJ, Ritchie AWS, Moussa SA, and Tolley DA: Incidental renal carcinoma discovered during ultrasound localisation of renal calculi for extracorporeal piezoelectric lithotripsy, Br J Urol 68: 211 (1991). 13. Thomson IM, and Peek M: Improvement in survival of patients with renal cell carcinoma-the role of the serendipitiously detected tumor, J Urol 140: 487 (1988). 14. Ritchie AWS, and deKernion JB: Incidental renal neoplasms: incidence in Los Angeles County, treatment and prognosis, in Schroder FH (Ed): Progress and Controversies in Oncological Urology, New York, Alan Liss Inc., II, 1988, p 347. 15. Selli C, Hinshaw W, Woodward BH, and Paulson DF: Stratification of risk factors in renal cell carcinoma, Cancer 52: 899 (1983).
UROLOGY
/ APRIL 1992
i
VOLUME
XxX1X.
NUMBER
4