Omission of elective neck irradiation in pT3-T4 oral squamous cell carcinoma with a pN0 neck: Impact on regional control and overall survival.

Abstract

e18091 Background: Postoperative radiotherapy is commonly indicated for the treatment of locally advanced oral squamous cell carcinoma (OSCC). However, for patients with a pN0 neck following cervical lymph node dissection, the American Society of Clinical Oncology (ASCO) guidelines suggest that adjuvant radiotherapy to cervical lymphatic regions may be omitted. Despite this recommendation, limited evidence supports this approach. This study aims to evaluate the impact of omitting neck irradiation on survival and locoregional control in patients with pT3-T4N0 OSCC following elective neck dissection. Methods: In this retrospective, single-institution cohort study, we included patients with locally advanced OSCC (pT3-T4N0) who underwent surgery, including cervical lymph node dissection. These patients received adjuvant tumor bed radiotherapy (RT) without postoperative neck irradiation. Collected data between January 2009 and December 2019 encompassed demographics, medical history, tumor characteristics, treatment details, and follow-up outcomes. Results: Seventy-seven patients were analyzed, with a mean age of 64.86 years (±12.87). Of these, 61% were male (n=47) and 39% female (n=30). The mean follow-up period was 56.35 months (±36.13). The median number of lymph nodes retrieved was 33 on the right side and 32.5 on the left. Recurrences were observed in 20.8% of patients (n=16), with no cases of isolated lymph node recurrence identified. Of the recurrences, 62.5% occurred at the primary tumor site, while 12.5% were isolated distant metastases. Lymph node recurrence occurred in combination with tumor site recurrence in 2 patients and pulmonary metastases in 1 patient. The median overall survival was 4 years (range, 0–13 years). Overall survival rates were 88.2% (95% CI: 78.5–93.7) at 2 years and 77.6% (95% CI: 66.5–85.5) at 5 years. The median recurrence-free survival was also 4 years, with rates of 84.7% (95% CI: 74.1–91.2) at 2 years and 79.2% (95% CI: 67.2–87.3) at 5 years. Conclusions: This study supports the omission of postoperative neck irradiation in patients with pT3-T4N0 OSCC who require adjuvant treatment, provided that the lymph node yield from neck dissection meets established quality standards (e.g., 18 or more lymph nodes). Omitting neck irradiation in pN0 OSCC patients reduces irradiated target volumes and associated toxicities without compromising survival or locoregional control.