Adverse effects after radiotherapy for early stage (I,IIa,IIb) seminoma

The evaluation of adverse effects after radiotherapy for early stage (I,IIa,IIb) seminoma.

A retrospective analysis of 164 patients with stage I, IIa, IIb seminoma treated with post-orchidectomy irradiation, between 1974 and 1990 was performed. Patients had been treated with infradiaphragmatic radiotherapy only (IDRT) in 48%, and prophylactic mediastinal and left supraclavicular irradiation (supradiaphragmatic radiotherapy, SDRT) was performed additionally in the remaining 52% of patients. Median follow-up was 12 years. The incidence of late morbidity was evaluated with respect to treatment-related factors like: PTV, number of fields irradiated each day, beam energy, total dose and dose per fraction. Afterwards, the dose distribution in normal tissues-based on dose per fraction at 3 cm depth and total dose at 3 cm depth, was evaluated in relation to late morbidity.

Overall 5-year and 10-year survival was 92 and 86%. For IDRT, dose per fraction at midline and dose per fraction from AP field at 3 cm depth were not significantly associated with Gastro-Intestinal morbidity. For SDRT, dose per fraction at 3 cm depth from AP field was significantly associated with cardiac morbidity (mean-1.98 Gy in patients without and 2.27 Gy in patients with cardiac morbidity P=0.006), however total dose at 3 cm was not significantly associated with cardiac morbidity. Dose per fraction at 3 cm depth from AP field significantly (P=0.047) influenced cardiac morbidity probability in multivariate logistic regression, which included patients' age, smoking habits and total dose at 3 cm.

Excessive dose maximum in normal tissues from each fraction to anterior mediastinum is associated with increased cardiac morbidity.