Purpose: The aim of this study was to review retrospectively the results of low-dose radiotherapy for Stage I seminoma using four different fractionation schedules and target volume definitions.
Methods and materials: A total of 191 patients underwent irradiation for histologically proven Stage I seminoma after undergoing an inguinal orchiectomy. Fractionation schedules were used one after another as follows: Total dose 30 Gy (dose/fraction 1.5 Gy, 16 patients), total dose 25.5 Gy (dose/fraction 1.5 Gy, 62 patients), total dose 20 Gy (dose/fraction 2 Gy, 69 patients), total dose 26 Gy (dose/fraction 2 Gy, 29 patients). The remaining 12 patients were excluded from this study. In the same period the target volume was gradually reduced. In 1983 the paraaortic, pelvic and inguinal regions were irradiated; later the target volume was reduced to the paraaortic region exclusively.
Results: Overall survival and event-free survival were identical in all groups ranging from 95% to 100% /5 years. Three patients experienced a lymph node metastasis during follow-up, 3 patients a distant metastasis to the lung and the bones. Mild acute side effects were noted in 8% to 15% of the patients, and very mild long-term side effects in 1% to 5% of patients. Multivariate analysis showed no prognostic significance of total dose, dose per fraction, or target volume. In univariate analysis, a higher frequency of acute side effects to the skin and the bowel was related to a higher total dose, and an elevated frequency of nausea was related to a higher daily dose per fraction.
Conclusion: Using lower doses and limiting the target volume to the paraaortic region exclusively did not result in a worse prognosis in our patient series.