794P UK Practices for Treatment of Relapse in Seminoma Testicular Cancer

Outcomes for men with stage I seminoma are excellent and avoiding intensive chemotherapy in these young patients is important. CT surveillance is a standard of care following orchiectomy. 10-20% relapse, but treatment is curative in almost 100%. In an ongoing trial of surveillance in seminoma [TRISST, NCT00589537], RMH stage IIC or worse relapse is defined as the primary outcome, reflecting the watershed for treatment with combination chemotherapy (BEP/EP) when TRISST was initiated. To re-assess the relevance of this endpoint we planned to assess current UK practices in treating relapse. In 2020, a survey of UK clinicians was conducted to determine factors affecting management decisions at relapse, and the treatments recommended according to tumour stage or size. 28 clinicians (24 centres) responded representing the majority of UK centres treating testicular cancer. 23 (82%) consider both stage and IGCCCG factors in determining relapse treatment, either with (57%) or without (25%) tumour size. In stage IIC disease, of 27 respondents, all indicated use of BEP/EP (3/4 cycle) or 3-4 cycles of carboplatin AUC10 (HDC); with only 3 (11%) also considering radiotherapy (RT, with carboplatin AUC7x1) as an option. Treatment of IIB disease was more varied: whilst 9 (of 27 respondents, 33%) only use BEP/EP and 5 (19%) only use HDC, 13 (48%) use RT +/- carboplatin AUC7 as either the only treatment (9, 33%) or as an option (4, 15%). However, when size is considered: for >3cm relapses, patterns were similar to IIC disease, but below 3cm management of stage IIB disease was less consistent. A subgroup of respondents use BEP/EP or HDC for all stage of seminoma relapse. 3 cycles of BEP is the most common combination regimen (20, 71%). In the UK, stage IIC remains a criterion for using intensive chemotherapy in relapsed seminoma. However, most clinicians also consider tumour size, with >3cm as a watershed between the use of intensive chemotherapy and locally-based treatments. As a result, detection of relapse >3cm has been added as key secondary endpoint in TRISST, with results due later in 2020. The trial will provide insights into current treatments at relapse and outcomes, as well as informing surveillance practices.