Treatment of stage I seminoma, with one course of adjuvant carboplatin or surveillance, risk-adapted recommendations implementing patient autonomy: a report from the Swedish and Norwegian Testicular Cancer Group (SWENOTECA)

A total of 1118 patients with clinical stage I seminoma one course of adjuvant carboplatin or managed by surveillance were included. Stromal invasion of rete testis and tumor size > 4 cm are confirmed as risk factors predicting relapse. Relapse rates following one course of adjuvant carboplatin is high and there is need to explore more effective adjuvant treatment options in patients with seminoma.The purpose of the protocol was to reduce the treatment burden in clinical stage I (CSI) seminoma by offering risk-adapted treatment. The protocol aimed to prospectively validate the proposed risk factors for relapse, stromal invasion of the rete testis and tumor diameter > 4 cm, and to evaluate the efficacy of one course of adjuvant carboplatin. From 2007 to 2010, 897 patients were included in a prospective, population-based, risk-adapted treatment protocol implementing one course of adjuvant carboplatin AUC7 (>n = 469) or surveillance (>n = 422). In addition, results from 221 patients receiving carboplatin between 2004 and 2007 are reported. At a median follow-up of 5.6 years, 69 relapses have occurred. Stromal invasion of the rete testis [hazard ratio (HR) 1.9, >P = 0.011] and tumor diameter > 4 cm (HR 2.7, >P < 0.001) were identified as risk factors predicting relapse. In patients without risk factors, the relapse rate (RR) was 4.0% for patients managed by surveillance and 2.2% in patients receiving adjuvant carboplatin. In patients with one or two risk factors, the RR was 15.5% in patients managed by surveillance and 9.3% in patients receiving adjuvant carboplatin. We found no increased RR in patients receiving carboplatin < 7 x AUC compared with that in patients receiving a parts per thousand yen7 x AUC. Stromal invasion in the rete testis and tumor diameter > 4 cm are risk factors for relapse in CSI seminoma. Patients without risk factors have a low RR and adjuvant therapy is not justified in these patients. The efficacy of adjuvant carboplatin is relatively low and there is need to explore more effective adjuvant treatment options in patients with high-risk seminoma. The data do not support the concept of a steep dose response for adjuvant carboplatin.