MP33-01: Risk of residual teratoma after complete response following first-line chemotherapy in men with metastatic non-seminomatous germ cell tumor and IGCCCG intermediate/poor prognosis: a multi-institutional retrospective cohort study
Introduction: Current guidelines recommend surveillance for men with metastatic non-seminomatous germ cell tumours (NSGCT) treated with first-line chemotherapy who had a complete clinical response to treatment (i.e., normalization of serum tumour markers and residual masses <1 cm). However, this recommendation is based on case series with classification by the 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 male patients with intermediate or poor IGCCCG-PG and complete clinical response after first-line chemotherapy. Methods: Retrospective study of men with intermediate or poor IGCCCGP-PG who had a complete clinical response after first-line chemotherapy. Men were followed or treated with post-chemotherapy retroperitoneal lymph node dissection (pcRPLND). Descriptive analyses and Cox regression were used to assess whether pcRPLND or surveillance leads to a longer overall survival (OS) for patients. Results: Between 2009–2018, 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 vital cancer in 16 (48%) and 4 (12%). During a median 7-year follow-up, 20/110 (18%) patients managed with surveillance relapsed, of whom 7 (6%) had a retroperitoneal-only relapse, vs 2/33 patients managed with pcRPLND relapsed. No difference was observed regarding 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. SOURCE OF Funding: None
