Objective: To determine the incidence of second non-germ-cell cancers (SNGC) in patients treated for stage I-II testicular seminoma.
Material and methods: This study is based on 131 evaluable patients treated at the Institut Claudius Regaud between 1970 and 1990. Treatment modalities, including salvage therapy for 6 patients developing recurrence, were as follows: infradiaphragmatic irradiation (infraDI) only in 55 cases, infra- and supradiaphragmatic irradiation (infraDI + supraDI) in 64 cases, and irradiation and chemotherapy (IC) in 12 cases. Five patients were lost to follow-up 4 months to 14 years after primary treatment (mean follow-up: 11 years). The cumulative incidence of SNGC was compared to the overall cancer incidence in the age-matched male population reported in the Tarn Cancer Registry. The relative risk was expressed as the Standardized Incidence Ratio (SIR).
Results: The cumulative incidence of SNGC was 10.7% (14/131 patients). SIR was equal to 2.81 (p < 0.001) and increased with the duration of follow-up. SIR was significantly increased in 64 patients treated with infraDI + supraDI (SIR) = 3.25; p = 0.002), but not in the 55 patients treated with infraDI only (SIR = 0.62; p = 0.8). The 12 treated patients with IC had an SIR of 26.2 (p < 0.001). Three of the 4 patients who developed a haematological malignancy belonged to the IC group.
Conclusions: The risk of SNGC is increased after infraDI + supraDI. The risk of SNGC after infraDI only is not increased with a median follow-up of 6 years, but this follow-up is too short to allow any definitive conclusions. The risk of SNGC and particularly haematological malignancy appears to be increased by the combination of radiotherapy and chemotherapy.