Second Hematologic Malignancies Associated With Primary Mediastinal Germ Cell Tumors: A Population-based Study.

BACKGROUND: Studies addressing second hematologic malignancies (SHMs) in patients with primary mediastinal germ cell tumors (PMGCTs) are scarce. To better describe this phenomenon, we analyzed a large case series from a population-based registry. METHODS: The Surveillance, Epidemiology, and End Results database was used to report the clinical characteristics and incidence of SHMs in patients with PMGCT. RESULTS: Among 1297 PMGCTs, 27 cases (2.08%) of SHM were found, with a median latency period of 12 months (95% CI: 5-41). All SHM occurred in males, 20 of whom (74.1%) had a previous nonseminomatous tumor. Acute myeloid leukemia was the most frequent SHM, accounting for 13 cases, 4 of which were acute megakaryoblastic leukemia that occurred within 5 months of diagnosis. The median survival after the diagnosis of SHM was 6 months (95% CI: 2-41). The risk of SHM was significantly higher than expected for the reference population, with a standardized incidence ratio of 6.21 (95% CI: 3.31-10.62) and an absolute excess risk of 19.19 per 10,000 person-years. CONCLUSIONS: Patients with PMGCT are at a higher risk of developing SHMs than the general population, particularly acute myeloid leukemia. This risk ranges from synchronous diagnosis of acute megakaryoblastic leukemia to the later onset of other hematological disorders that might be related to PMGCT therapies. Our findings may help create follow-up schedules for patients with PMGCT and raise the level of suspicion surrounding this association.

Extragonadal Germ Cell Tumors of the Mediastinum and Retroperitoneum: A Surveillance, Epidemiology, and End Results-based Study.

OBJECTIVES: Extragonadal germ cell tumors (EGCT) are a rare entity, most of them being located in the mediastinum and retroperitoneum. Information on these tumors is scarce, requiring carrying out large population-based studies to better understand these diseases. We aimed to determine the clinical features and prognosis of patients with EGCT of the mediastinum and retroperitoneum. MATERIALS AND METHODS: Demographic and clinicopathological features of patients diagnosed with EGCT of the mediastinum and retroperitoneum from 1975 to 2016 were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. RESULTS: A total of 1674 patients were included, 1297 (77.5%) of mediastinal origin and 377 (22.5%) of retroperitoneum. Nonseminomatous tumors (56.3%) were slightly more frequent than seminomas (43.7%) with similar distribution between mediastinum and retroperitoneum. After a median follow-up of 137 months, the median overall survival was 263 months (95% CI, 220-296) whereas the median cause-specific survival (CSS) has still not been reached. The 10-year overall survival and CSS were 57.4% (95% CI, 55-59.7) and 63% (95% CI, 60.6-65.2) respectively. Multivariate analysis showed that older age, mediastinal location, nonseminomatous histology, and distant disease at diagnosis were independent prognostic factors correlated with a worse prognosis. Patients with mediastinal choriocarcinoma and embryonal carcinoma have the worst prognosis, both with a median CSS of only 12 months. CONCLUSIONS: Despite a decreasing incidence observed in recent decades, EGCT continues to represent a challenge for oncologists. The prognosis of choriocarcinoma and embryonal carcinoma of the mediastinum remains poor and treatment strategies need to be improved urgently.