Work

Early Salivary Gland Shrinkage Is Associated With an Increased Risk of Acute Xerostomia in Head and Neck Cancer Radiation Therapy

Year: 2026

Type: article

Abstract: Purpose To investigate the relationship between geometric and dosimetric characteristics of salivary glands and acute xerostomia during or shortly after radiotherapy in head and neck cancer (HNC) patients. Materials/Methods We utilized an Automated Watchdog in Adaptive Radiotherapy Environment (AWARE) program to monitor changes in tumor and organ-at-risk (OAR) using weekly CBCT images for HNC patients. GTV and OAR contours were propagated from the planning CT to the weekly CBCT using deformable registration and reviewed by clinical users. This study analyzed 165 evaluable AWARE-HNC patients treated between 2021 and 2024. The National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 was employed to grade toxicities. Acute xerostomia was defined as grade ≥2, occurring during or within 3 months after radiotherapy completion. We compared weekly salivary (parotid and submandibular) gland shrinkage and radiation doses between patients with and without acute xerostomia. Results Of the 165 HNC patients, 66 (40.0%) developed acute xerostomia. Patients with acute xerostomia exhibited significantly larger parotid gland shrinkage in the 2 nd and 3 rd weeks and submandibular gland shrinkage in the 2 nd week (15.4%, 21.0%, and 13.1%, respectively; t-test P=0.047, 0.032, and 0.007) during radiotherapy, compared to those without acute xerostomia (11.4%, 17.2%, and 7.7%). Compared to the non-xerostomia group, patients who developed acute xerostomia received significantly higher mean doses to the ipsilateral parotid (24.7Gy vs. 19.8Gy, P=0.003) and ipsilateral submandibular glands (60.7Gy vs. 57.4Gy, P=0.045). Lower parotid dose in the cone-down boost and subsequent adaptation mitigated the risk of acute xerostomia (P=0.015). Conclusion Increased mean doses to the ipsilateral parotid and submandibular glands were associated with larger salivary gland shrinkage during radiotherapy and a significantly higher risk of acute xerostomia. This early signal could trigger adaptive replanning promptly. Cone-down and adaptive techniques can reduce the salivary gland dose, helping mitigate the risk of acute xerostomia.

Source: Advances in Radiation Oncology

DOI: 10.1016/j.adro.2026.102090