The Rare Entity of Basaloid Thymic Carcinoma: A Multicentric Retrospective Analysis from the Italian Collaborative Group for ThYmic MalignanciEs (TYME).

Simple Summary: Basaloid thymic carcinoma (BTC) is an extremely rare tumor, and very little data are available on its clinical behavior, drug sensibility, and patients' outcome. We retrospectively collected demographical, clinical, and pathological data of all consecutive patients previously diagnosed with BTC at TYME-referral institutes from 2008 to 2023. Twenty-eight patients with BTC were identified. A total of 22/28 patients were included in this analysis. BTC is generally diagnosed as a localized disease, and no alterations in actionable targets or microsatellite instability were identified. Patients with stage I–III BTC can achieve long-term DFS, and efforts should be made to perform radical surgical resection, combined with perioperative treatment when appropriate. Patients with advanced disease progression have shown a high response rate to systemic treatments, but they have a poor prognosis. Background: thymic basaloid carcinoma (BTC) is an extremely rare tumor, and very little data are available on BTC's biology, clinical behavior, drug sensitivity, and patient outcomes. Methods: We performed a retrospective observational study on patients diagnosed with BTC in 11 referral centers of TYME. All BTC diagnoses were reviewed by the referring pathologist. Results: Twenty-eight patients were identified. A total of 22/28 patients were included. Eighteen patients had TNM stage I–III disease, and all underwent surgery; three patients received preoperative chemotherapy, and 10 patients received adjuvant radiotherapy. With a median follow-up of 46 (1–133) months, median overall survival (mOS) and median relapse-free survival were not reached. At 48 months, OS was 77% (95%CI 43–92), and DFS was 63% (95%CI 30–83). The median OS of the 4 patients diagnosed with metastatic disease was 7 months. Six patients received first-line systemic treatment for metastatic disease, and all showed tumor responses. Anti-tumor activity was also observed with an anti-VEGFR TKI and a multi-TKI inhibitor combined with an anti-PD1 antibody. Next-generation sequencing performed in three tumor samples did not identify actionable alterations or microsatellite instability. Conclusions: BTC is an extremely rare tumor that usually presents as a localized disease. Patients diagnosed with stage I–III disease can achieve long-term DFS, and efforts should be made to perform radical surgical resection combined with perioperative treatment whenever appropriate. Patients with advanced disease progression have a poor prognosis despite a high response rate to systemic treatments. [ABSTRACT FROM AUTHOR]