High-dose chemotherapy with autologous stem-cell transplantation for relapsed metastatic germ cell tumors: The Alberta experience.

INTRODUCTION: High-dose chemotherapy with autologous stem-cell transplantation (HDCASCT) is standard therapy for metastatic germ cell tumors (mGCTs) in patients whose disease progresses during or after conventional chemotherapy. We conducted a retrospective review of HDC-ASCT in relapsed mGCT patients in the province of Alberta, Canada over the past two decades.

METHODS: Patients with mGCTs who received HDC-ASCT at two provincial cancer referral centers from 2000-2018 were identified from institutional databases. Baseline clinical and treatment characteristics were collected, as well as overall survival (OS) and disease-free survival (DFS). Relevant prognostic variables were analyzed.

RESULTS: Forty-three patients were identified. The median age was 28 years (range 19-56). A majority (95%) had non-seminoma histology and testis/retroperitoneal primary (84%). Twenty patients (47%) had poor-risk disease, as per The International Germ Cell Consensus Classification (IGCCC), at start of first-line chemotherapy. HDC-ASCT was used as second-line therapy in 65% of patients, and 58% of ASCT patients received tandem transplants. Median followup after ASCT was 22 months (range 2-181). At last followup, 42% of patients were alive without disease, including 3/7 (43%) of patients with primary mediastinal disease. Two-year and five-year DFS/OS ratios were 44%/65% and 38%/45%, respectively. Median OS and DFS for all patients were 30.0 months (13.3-46.6) and 8.0 months (0.9-15.1), respectively.

CONCLUSIONS: We found that HDC-ASCT is an effective salvage therapy in mGCT, consistent with existing literature. Patients appeared to benefit regardless of primary site. Though limited by small sample size, we found a numerical difference in DFS and OS between second- and third-line HDC-ASCT and single vs. tandem ASCT.