Risk of residual cancer after complete response following first-line chemotherapy in men with metastatic non-seminomatous germ cell tumour and International Germ Cell Cancer Cooperative Group intermediate/poor prognosis: A multi-institutional retrospective cohort study.

INTRODUCTION:Current guidelines recommend surveillance in metastatic non-seminomatous germ cell tumour patients treated with first-line-chemotherapy and a complete clinical response (normalisation of serum tumour markers and residual masses <1 cm). However, this recommendation is based on a series including patients with good prognosis according to International Germ Cell Cancer Cooperative Group prognostic group (IGCCCG-PG). The aim of this study was to analyse the proportion of residual teratoma and survival among patients with intermediate/poor IGCCCG-PG and a complete clinical response after first-line-chemotherapy. MATERIAL & METHODS:This is a retrospective study of men with intermediate/poor IGCCCG-PG, who had a complete clinical response after first-line chemotherapy. Patients were either followed by surveillance or treated with post-chemotherapy retroperitoneal lymph node dissection (pcRPLND). RESULTS:Between 2009 and 2018, 143 men with intermediate (n = 83) or poor (n = 60) IGCCCG-PG were treated at 11 international centres. Among 33 patients treated with pcRPLND, the specimen showed teratoma and viable cancer in 16 (48%) and 4 (12%). During a median a 7-year follow-up, 20/110 (18%) patients managed with surveillance relapsed, of whom seven (6%) had a retroperitoneal-only relapse versus 2/33 patients managed with pcRPLND relapsed. No difference was observed regarding overall survival (OS) among men treated with pcRPLND or surveillance (5-year OS, 93% and 89%, p-value = 0.35). The median time-to-recurrence among men on surveillance was 1.3 years (range: 0.3-9.1), and the most common sites of relapses included retroperitoneum (11%), chest (5%), and bones (4%). CONCLUSIONS:While most men with intermediate/poor IGCCCG-PG harbour teratoma/cancer in the retroperitoneum despite a complete response to first-line-chemotherapy, only 6% managed with surveillance relapsed in the retroperitoneum. There was no significant difference in OS between the two groups.