Background: The NCCN 2010 guidelines recommend the use of postoperative adjuvant radiotherapy (RT) for patients with pT3 oral cavity squamous cell carcinoma (OSCC). We sought to determine whether postoperative adjuvant RT improves outcomes in pT3N0 OSCC patients.
Methods: A total of 119 consecutive patients with pT3N0 disease were involved. A total of 42 patients received postoperative adjuvant RT, while the remaining 77 did not. The 5-year rates of control, distant metastasis, and survival were the main outcome measures.
Results: We found no differences in the risk profile of patients with and without postoperative adjuvant RT, the only exceptions being a higher frequency of tumor depth ≥10 mm (78.6% vs. 48.0%, P = .001) and close margins ≤4 mm (11.9 % vs. 2.7%, P = .043) in those treated by adjuvant RT. Tumor depth ≥10 mm was the only independent prognostic factor for 5-year local control, disease-free survival, and disease-specific survival in multivariable analysis. Tumor depth ≥13 mm was the only independent prognostic factor for the 5-year rate of distant metastases (16% [7 of 50] vs. 2% [1 of 67]). After stratification for tumor depth and adjuvant RT, patients with pT3N0 disease who received adjuvant RT did not show a survival advantage.
Conclusions: Tumor depth ≥10 mm was the only prognostic factor identified in patients with pT3N0 disease. Adjuvant RT did not improve outcomes in pT3N0 patients, regardless of tumor depth. Patients with pT3N0 and tumor depth ≥13 mm (43% of pT3N0) were at the highest risk for distant metastases.