Purpose: A binational, population-based treatment protocol was established to prospectively treat and follow patients with seminomatous testicular cancer. The aim was to standardize care for all patients with seminoma to further improve the good results expected for this disease. Patients and Methods From 2000 to 2006, a total of 1,384 Norwegian and Swedish patients were included in the study. Treatment in clinical stage 1 (CS1) was surveillance, adjuvant radiotherapy, or adjuvant carboplatin. In metastatic disease, recommended treatment was radiotherapy in CS2A and cisplatin-based chemotherapy in CS2B or higher. Results At a median follow-up of 5.2 years, 5-year cause-specific survival was 99.6%. In CS1, 14.3% (65 of 512) of patients relapsed following surveillance, 3.9% (seven of 188) after carboplatin, and 0.8% (four of 481) after radiotherapy. We could not identify any factors predicting relapse in CS1 patients who were subjected to surveillance only. In CS2A, 10.9% (three of 29) patients relapsed after radiotherapy compared with no relapses in CS2A/B patients (zero of 73) treated with chemotherapy (P = .011). Conclusion An international, population-based treatment protocol for testicular seminoma is feasible with excellent results. Surveillance remains a good option for CS1 patients. No factors predicted relapse in CS1 patients on surveillance. Despite resulting in a lower rate of relapse than with adjuvant carboplatin, adjuvant radiotherapy has been abandoned in the Swedish and Norwegian Testicular Cancer Project (SWENOTECA) as a recommended treatment option because of concerns of induction of secondary cancers. The higher number of relapses in radiotherapy-treated CS2A patients when compared with chemotherapy-treated CS2A/B patients is of concern. Late toxicity of cisplatin-based chemotherapy versus radiotherapy must be considered in CS2A patients.
2011. Vol. 29, no 6, 719-725 p.