904P - Retrospective analysis of adjuvant systemic anti-hormonal therapy for resected androgen receptor-positive (AR+) salivary duct carcinoma (SDC)

Background

Salivary duct carcinoma (SDC) is one of the salivary gland cancers. Standard treatment consists of tumor resection followed by post-operative radiotherapy. Approximately 70% of patients experience recurrent/metastatic (R/M) disease. The added value of adjuvant androgen deprivation therapy (ADT) or combined androgen blockade (CAB) has already been studied in a small cohort (n=22), showing increased 3-year disease-free survival (DFS) as compared to a historical cohort. Here, we retrospectively investigated whether adjuvant systemic anti-hormonal therapy is beneficial for DFS and overall survival (OS) in a larger poor-risk SDC cohort.

Methods

The adjuvant-treated cohort described by Van Boxtel et al. (2019) was extended with 40 resected stage IV A/B SDC patients that have been treated with adjuvant ADT/CAB at Radboudumc between 2014 and January 2023. Treatment consisted of bicalutamide, goserelin, or a combination of both. The historical cohort was not modified nor expanded (n=114). The endpoints included DFS and OS.

Results

Sixty-one patients were treated with adjuvant ADT/CAB, with a median duration of therapy of 12 months. Differences in DFS/OS between adjuvant ADT and CAB have not been found. Median follow-up for the adjuvant patients was 24 months (range: 0 – 114 months) and 30 months for the control cohort (range: 0 – 216 months). Adjuvant-treated patients had longer mDFS and mOS as compared to the historical cohort (mDFS: 33 months [95% CI 6.5 – 59.5] vs. 20 months [95% CI 15.3 – 24.7; HR 0.676, 95% CI 0.433 – 1.057; p=0.086]; mOS: 73 months [95% CI 43.8 – 102.2] vs. 45 months [95% CI 32.8 – 57.2; HR 0.595, 95% CI 0.343 – 1.033; p=0.060]). The adjuvant-treated patients generally exhibited better DFS and OS at 3 years than the control group (adjuvant: 46% and 68%, respectively, control: 33% and 54%, respectively).

Conclusions

Poor-risk AR+ SDC patients treated with adjuvant systemic anti-hormonal therapy showed prolonged, however not significant, DFS and OS as compared to non-adjuvant treated historical controls.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Radboudumc.

Funding

Has not received any funding.

Disclosure

L.A. Devriese: Financial Interests, Institutional, Advisory Board: InCyte, MSD. J.A. Schalken: Financial Interests, Institutional, Speaker, Consultant, Advisor: Astellas, Bayer. C.M.L. Van Herpen: Financial Interests, Institutional, Advisory Board: Bayer, Bristol Myers Squibb, Elevar, Ipsen, MSD, Regeneron; Financial Interests, Institutional, Research Grant: AstraZeneca, Bristol Myers Squibb, MSD, Merck, Ipsen, Novartis, Sanofi. All other authors have declared no conflicts of interest.