The ABC-study

Background & rationale

One course of adjuvant carboplatin AUC7 is considered internationally to be a standard treatment option in clinical stage I seminoma, regardless of risk factors. This is based on a large randomized phase III study comparing adjuvant carboplatin with adjuvant radiotherapy, which estimated a relapse rate following carboplatin of 5.3%.

Data from a prospective, risk-adapted Spanish study showed that patients without risk factors had a very low risk of relapse even without adjuvant treatment — confirmed by analysis of SWENOTECA VII data showing a relapse risk of less than 5% without treatment. The same data estimated a relapse rate of about 20% in patients with one or two risk factors followed by surveillance.

Combined SWENOTECA V and VII data indicate a 65% relapse-rate reduction with one course of adjuvant carboplatin (9.4% vs 22%) in patients with one or two risk factors (tumour > 4 cm, stromal invasion of rete testis). Based on these results, the SWENOTECA IX guidelines recommend adjuvant carboplatin AUC7 for patients with risk factors and surveillance for those without.

However, due to the modest effect of carboplatin, SWENOTECA launched the ABC trial to explore a more efficient strategy. One course of BEP — highly potent in the adjuvant non-seminoma setting (90–95% relapse reduction) — is compared with one course of carboplatin in seminoma CS I. With an expected low relapse rate, possibly close to 1%, SWENOTECA believes the higher acute toxicity of one BEP is outweighed by its greater efficacy. The trial aimed to include 348 patients over 54 months, with all major centres in Norway and Sweden participating.

Study office & contact

Questions regarding the study, requests for Ledidi access and SAE reports can be directed to the study office: abc@stolav.no

Completed questionnaires should be sent by mail to the study office: