Purpose: To measure the incidence of second non-germ cell malignancies (SNGCM) in patients treated for a stage I-II testicular seminoma.
Materials and methods: From 1970 to 1992, 131 evaluable patients received in the Institut Claudius Regaud a post-orchiectomy treatment for a stage I-II testicular seminoma. The therapeutic modalities, including salvage treatment for six recurrences, were as follows: infradiaphragmatic radiotherapy (IDRT) (n = 55); infra- and supradiaphragmatic radiotherapy (IDRT + SDRT) (n = 64); IDRT + SDRT with chemotherapy (n = 12). The mean follow-up was 11 years. The cumulative incidence of SNGCM was compared to the overall cancer incidence in the general male population on the basis of the Tarn Cancer Registry; the relative risk was expressed as a standardized incidence ratio (SIR).
Results: Overall, the cumulative incidence of SNGCM was 10.7% (14/131 cases). The SIR was equal to 2.81 (95% confidence interval (CI) 1.54-4.72; P < 0.001) and increased with follow-up duration. The SIR was significantly increased in 64 patients treated with IDRT + SDRT (SIR = 3.08; 95% CI 1.47-5.66; P = 0.002) but not in 55 patients treated with IDRT alone (SIR = 0.62; 95% CI 0.01-3.43; P = 0.8). The 12 patients who received chemotherapy had an SIR of 26.2 (95% CI 5.48-77.69; P < 0.001), while the SIR was 2.26 in the 119 patients who did not receive any chemotherapy (95% CI 1.13-4.04; P = 0.01 ). Of four hematologic malignancies, three appeared in the 12 patients who received chemotherapy.
Conclusions: An increased risk of SNGCM after SDRT + IDRT has been demonstrated. After IDRT alone, the risk of second cancer is not incremented after a median follow-up of 6 years, but further observation of the patients is necessary to achieve final conclusions. Our results suggest that the risk of second cancer and especially of hematologic malignancy is increased by the association of chemotherapy and radiation.