Main Session

Sep 29

PQA 07 - Head and Neck Cancer, Lung Cancer/Thoracic Malignancies, and Nursing and Supportive Care

3497 - Modern Adjuvant Radiotherapy for Carcinoma Ex Pleomorphic Adenoma of the Lacrimal and Salivary Glands: A Multi-Institutional Study

03:45pm - 05:00pm ET

Poster Hall - Exhibit Hall A

Screen: 15

POSTER

Presenter(s)

Rodney Cheng-En Hsieh, MD, PhD - Chang Gung Memorial Hospital Linkou Branch, Taoyuan City, Taiwan

R. C. E. Hsieh¹, L. Y. Lee², P. W. Hsu³, and K. P. Chang³; ¹Department of Radiation Oncology, Chang Gung Memorial Hospital at Linkou, Taoyuan City, Taiwan, ²Department of Pathlogy, Chang Gung Memorial Hospital at Linkou, Taoyuan, Taiwan, ³Chang Gung Memorial Hospital at Linkou, Taoyuan city, Taiwan, Taiwan

Purpose/Objective(s): This multi-institutional study aimed to investigate the role of modern adjuvant radiotherapy in surgically resected lacrimal and salivary gland carcinoma ex pleomorphic adenoma (CXPA).

Materials/Methods: This retrospective analysis included 117 patients with surgically resected CXPA of the lacrimal and salivary glands treated at five academic hospitals between 2000 and 2024. Eighty-three patients (71%) underwent adjuvant radiotherapy (proton, n = 7; intensity-modulated radiotherapy, n = 65; three-dimensional conformal radiotherapy, n = 11). Tumors originated from the parotid (n = 60), submandibular (n = 33), lacrimal (n = 12), minor salivary (n = 10), and sublingual (n = 2) glands.

Results: After a median follow-up of 72 months, the 5-year locoregional control (LRC), progression-free survival (PFS), and overall survival (OS) rates were 79%, 60%, and 69%, respectively. On multivariable analysis, the use of adjuvant radiotherapy was significantly associated with improved LRC (P = .038), PFS (P = .023), and OS (P = .046). Age, performance status, and N stage independently predicted PFS and OS, while positive resection margins were associated with worse LRC and PFS. Perineural invasion was associated with inferior OS, and lymphovascular invasion predicted lower LRC. In subgroup analyses, patients with positive resection margins who received adjuvant radiotherapy had significantly higher 5-year LRC (74% vs 53%, P = .046), PFS (57% vs 19%, P = .003), and OS (68% vs 29%, P = .002) rates compared with those treated with surgery alone. Additionally, adjuvant radiotherapy was associated with superior 5-year LRC (73% vs 43%, P = .015) and PFS (48% vs 25%, P = .020) among patients with T3–4 disease.

Conclusion: Modern adjuvant radiotherapy was associated with improved oncologic outcomes in patients with adverse pathological features, particularly positive resection margins and advanced T stage.