Incidence of secondary malignancies (SM) in patients (pts) with germ cell tumors (GCT) who received high-dose chemotherapy (HDCT): A retrospective study from the European Society for Blood and Marrow Transplantation (EBMT) database

409 Background: Little is still known about the incidence of SM in young adult pts with GCT after HDCT, owing to the rarity of the disease, and the need for long term follow-up (FUP) data registries. In Europe, the EBMT systematically collect relevant data and may provide a suitable platform for retrospective analyses. Methods: Criteria for patient selection included diagnosis of GCT, adult male gender, ≥ 2yr of FUP after the administration of HDCT. Summary statistics were used to describe pt characteristics and outcomes. χ2 tests were used to compare groups according to the length of FUP. Kaplan-Meier estimates were used to estimate overall survival (OS) since the diagnosis of SM. Log-rank test was used to compare OS in pt subgroups. Univariable Cox regression analyses examined clinical factors potentially associated with OS following SM diagnosis. Results: From 1981 to 2014, 9,153 autografts, accounting for 5,100 pts, have been registered. Of them, 1,855 had ≥ 2yr of FUP. Among the latter, a total of 56 cases of SM were identified (3.0%). 28 (50%) had solid SM, 22 (39.3%) hematologic SM (5 had uncoded SM). Median age at first HDCT was 34 years (IQR: 30-42), median age at development of SM was 42 (37-51). 26 pts (46.4%) received single HDCT cycle, 22 (39.3%) multiple HDCT cycles (8 unknown). 31 pts had ≥ 5 yr FUP, 25 pts 2-5 yr FUP. Solid SM were developed more frequently in those with longer FUP ( ≥ 5 yrs) compared to hematologic SM (p = 0.008). Median follow-up (FUP) was 76.9 months. Univariably, the type of SM (solid vs. hematologic) was significantly associated with OS. Hematologic vs solid SM: HR: 3.49 (95%CI: 2.09-10.47, p < 0.001). Median OS of pts who developed solid SM was 32.8 months compared to 7 months of those with hematologic SM. The retrospective nature of the data is the major limitation. Conclusions: The incidence of SM in GCT pts who have received HDCT is a concern. During the FUP, there seems to be a non-overlapping risk of developing solid or hematologic SM, with a significantly different prognostic impact. These data may be important to improve patient counselling and the planning of post-HDCT FUP.