1092 - Clinical Outcome and Toxicities of Post-Operative Hypofractionated Intensity Modulated Radiation Therapy for Oral Cavity Squamous Cell Carcinoma: A Phase II Study

Purpose/Objective(s): Current standard for oral cavity squamous cell carcinoma (OCSCC) is surgery with or without adjuvant radiotherapy/chemoradiotherapy. There is paucity of prospective evidence for adjuvant hypo-fractionated intensity modulated radiotherapy (H-IMRT) for OCSCC. We aimed to assess toxicities and loco-regional control (LRC) in OCSCC treated with adjuvant H-IMRT in this prospective phase II study.

Materials/Methods: 25 patients (February 2023 - August 2024) of post-operative OCSCC treated with H-IMRT were recruited in this trial (CTRI/2023/02/049519). 56 Gray (Gy) to high risk planning target volume (HR_PTV) and 48 Gy to low risk planning target volume (LR_PTV), both in 22 fractions over four weeks were prescribed. Patients with indication of concurrent chemotherapy were excluded. Acute toxicity was graded as per CTCAE, v5.0 and late toxicities as per RTOG scoring criteria. Quality of life and dysphagia was scored with FACT-HN and MDADI at baseline before start of radiotherapy (B), completion of radiotherapy (RTCom) and 6 months following completion of radiotherapy (RT-6). LRC was calculated from the date of surgery.

Results: Median age was 45years (30-73 yr). Primary site was buccal mucosa (56%), tongue (40%) and gingiva (4%). Stage distribution was I-II (24%), III (48%) and IVA (28%). Table 1 shows dosimetric parameters. Median overall treatment time (OTT) and RT duration were 92 days (63-106) and 31 days (28 -42) respectively. Grade 2 acute radiation dermatitis, oral mucositis, dysphagia, and oral pain was noted in 3 (12%), 12 (48%), 21 (84%) and 23 (92%) patients respectively. Acute grade 3 oral mucositis and dysphagia was noted in 13 (52%) and 3 (12%) patients respectively. Grade1 xerostomia and neck fibrosis was noted in 14 (70%) and 5 (25%) patients respectively. Mean FACT-HN at B, RTCom and RT-6 was respectively 77.2±8, 75.59±8.4 and 81±4.8. Mean MDADI score at B, RTCom and RT-6 were 78.3±11.4, 63.8±8.7 and 83.94±6.1 respectively. Median follow up was 14.5 months (range 5-18 months). 1-year LRC was 92.9%. 2 patients failed loco-regionally and one had distant metastasis at last follow up.

Conclusion: Adjuvant H-IMRT for OCSCC is well tolerated with acceptable acute toxicity profiles and good short term clinical outcome.