Purpose: Improved survival in testicular cancer has been accompanied by concern about long-term side effects of therapy. We assessed the evolution of second cancer (SC) risk over a prolonged follow-up period, which has been rarely studied in large patient series.
Patients and methods: We estimated the risk of SCs in 1,909 patients with testicular cancer diagnosed in the Netherlands from 1971 to 1985. Complete medical information was obtained up to at least January 1988 for 92% of patients. Median follow-up was 7.7 years. For 89% of second tumors the diagnosis was confirmed through review of histologic slides; for an additional 8%, the diagnosis was verified by pathology reports only.
Results: Seventy-eight patients developed a SC 1 year or more after start of treatment, as compared with 47.6 expected on the basis of incidence rates in the general population (relative risk [RR], 1.6; 95% confidence interval [CI], 1.3 to 2.1). The mean 15-year actuarial risk of all SCs was 9.8% (95% CI, 7.5% to 12.8%). Significantly increased RRs were observed for all gastrointestinal cancers combined (RR, 2.6; 95% CI, 1.7 to 3.9), stomach cancer (RR, 3.7; 95% CI, 1.8 to 6.8), contralateral testicular cancer (CLTC) (RR, 35.7; 95% CI, 21.8 to 55.2), and leukemia (RR, 5.1; 95% CI, 1.4 to 13.0). Patients who had received irradiation to the paraaortic lymph nodes and who survived testicular cancer for more than 5 years were at particularly high risk of developing stomach cancer (RR, 6.9; 95% CI, 3.3 to 12.7). The median interval between the diagnosis of testicular cancer and stomach cancer was 12.4 years. Patients treated with chemotherapy (CT) did not experience an increase in SCs in general. Indeed, CT-treated patients, as compared with those who received radiotherapy (RT), or surgery alone, had significantly reduced risk of CLTC. This finding might be attributed to an eradicating effect of CT on carcinoma in situ or subclinical CLTC. The excess risk of leukemia was not found to be clearly related to CT.
Conclusion: Testicular cancer patients who receive RT experience elevated risk of gastrointestinal tumors. CT does not seem to increase SC risk and may even decrease the risk of a CLTC. Following testicular cancer, the 15-year actuarial risk of all SCs is only about half the risk experienced by patients with Hodgkin's disease.