Can superficial parotid sparing alone impact xerostomia in head and neck cancer? A retrospective study correlating the type of tobacco use, chronic xerostomia, and parotid sparing

Background: Head and neck cancer is one of the most common cancers in India, with tobacco chewing being the predominant form of tobacco consumption. We aimed to assess the impact of superficial gland sparing on xerostomia. Materials and methods: Patients with histopathological diagnosis of head and neck cancer treated with curative intent radiotherapy with intensity-modulated radiotherapy (IMRT) to a dose of 60–70 Gy in 30–35 fractions with or without chemotherapy from June 2017 to March 2020 were included in the study. The superficial and deep lobes of the parotid were contoured retrospectively. The physician-reported Radiation Therapy Oncology Group (RTOG) xerostomia toxicity grades at two years were retrieved from records. Results: One hundred seventy-four patients were included in the study. Tobacco chewing was the most common form of use, followed by smoking. Tobacco chewers had significantly smaller mean parotid (53cc vs. 60cc, p = 0.02) and mean submandibular gland volumes (6 cc vs. 14 cc, p < 0.001) as compared to smokers. Bilateral or contralateral parotid sparing (mean dose < 26 Gy) was achieved in 62.7%, bilateral or contralateral superficial lobe in 27.6% and no sparing in 9.8% of patients. The xerostomia was similar in smokers and chewers (p = 0.95). Patients with bilateral or contralateral superficial lobe sparing had lower grade II/III xerostomia rates than the no-sparing group (p = 0.038). Conclusions: Tobacco chewers have smaller volumes of salivary glands. Contralateral or bilateral superficial parotid sparing translated into better xerostomia scores at two years.