Can adjuvant radiotherapy be omitted for oral cavity cancer patients who received neoadjuvant therapy and surgery? A retrospective cohort study

Surgery and postoperative adjuvant therapy comprise the standard treatment for locally advanced resectable oral squamous cell carcinoma (LAROSCC), while preoperative neoadjuvant therapy is being explored without sufficient confirmation of improved survival. De-escalation regimens after neoadjuvant therapy, such as those omitting adjuvant radiotherapy, may provide comparable or better outcomes, suggesting rigorous assessment of adjuvant therapy outcomes is needed in LAROSCC patients. The authors thus performed this retrospective study in LAROSCC patients who received neoadjuvant therapy and surgery, to compare the outcomes for overall survival (OS) and locoregional recurrence-free survival (LRFS) between the adjuvant radiotherapy (radio) and nonradiotherapy (nonradio) cohorts. MATERIALS AND METHODS: Patients diagnosed with LAROSCC who received neoadjuvant therapy and surgery were enrolled and divided into radio and nonradio cohorts to determine whether adjuvant radiotherapy could be omitted after neoadjuvant therapy and surgery. RESULTS: From 2008 to 2021, 192 patients were enrolled. No significant differences were found in OS or LRFS between the radio and nonradio patient cohorts. The 10-year estimated OS rates were 58.9 versus 44.1% in radio versus nonradio cohorts, while 10-year estimated LRFS rates were 55.4 versus 48.2%, respectively. For clinical stage III patients, 10-year OS rates were 62.3 versus 62.6% (radio vs. nonradio), and estimated 10-year LRFS rates were 56.5 versus 60.7% (radio vs. nonradio). Multivariate Cox regression modeling of postoperative variables showed pathologic response of primary tumor and pathologic regional lymph nodes staging were associated with survival, while the adjuvant radiotherapy exposure was not included in the model due to nonsignificance. CONCLUSION: These findings support further prospective evaluation of adjuvant radiotherapy omission, and suggest that de-escalation trials are warranted for LAROSCC surgery patients who received neoadjuvant therapy.