Second primary malignancies in T1-3N0 prostate cancer patients treated with radiation therapy with 10-year followup

The risk of patients with prostate cancer to have second primary malignancies is unclear. Population and autopsy based studies have shown no increased risk, which is at variance with several institutional analyses. A retrospective review was performed with comparison to expected cancer data from the Connecticut Tumor Registry.

Records of a cohort of prostate cancer patients treated with staging pelvic lymphadenectomy and definitive radiotherapy between November 1, 1974 and July 7, 1987 were reviewed. Median potential followup from date of diagnosis was 10.9 years.

Of the 164 patients 150 (91.5%) had followup to death or to August 1995, with data available in part on 4 of the remaining patients. In 43 patients 51 second primary malignancies developed. Increased frequency of lymphomas, and kidney, bladder and rectal lesions (all p < 0.001) was observed concurrently with diagnosis of prostate cancer, although this may be due to bias since full staging for the prostate cancer may have led to their diagnosis. An increased frequency of renal lesions in the 1 to 4-year followup period (p = 0.032) also was observed. Two sarcomas and a leukemia were putatively radiation induced but their frequency was not significantly different from the comparison baseline.

Much of the apparent increase in second primary malignancies associated with prostate cancer noted by some authors may be attributed to bias in the staging process. Renal cancers may occur more frequently in patients with prostate cancer but the distribution of these lesions is inconsistent with a field defect mechanism of cancer induction.