Stage II Oral Tongue Cancer: Survival Impact of Adjuvant Radiation Based on Depth of Invasion.

OBJECTIVE: To determine if adjuvant radiation therapy for patients with pT2N0 oral cavity tongue cancer affects overall survival.

STUDY DESIGN: Retrospective cohort study.

SETTING: National Cancer Database.

SUBJECTS AND METHODS: Cases diagnosed between 2004 and 2013 with pathologic stage pT2N0 oral cavity tongue cancer with negative surgical margins were extracted from the National Cancer Database. Data were stratified by treatment received, including surgery only and surgery + postoperative radiation therapy. Univariate analysis was performed with a 2-sample t test, chi-square test, or Fisher exact test and log-rank test, while multivariate analysis was performed with Cox regression models adjusted for individual variables as well as a propensity score.

RESULTS: A total of 934 patients were included in the study, with 27.5% of patients receiving surgery with postoperative radiation therapy (n = 257). In univariate analysis, there was no significant difference in 3-year overall survival between the patient groups ( P = .473). In multivariate analysis, there was no significant difference in survival between the treatment groups, with adjuvant radiation therapy having a hazard ratio of 0.93 (95% CI, 0.60-1.44; P = .748). Regarding tumors with a depth of invasion >5 mm, there was no survival benefit for the patients who received postoperative radiation therapy as compared with those who received surgery alone (hazard ratio = 0.93; 95% CI, 0.57-1.53; P = .769).

CONCLUSION: An overall survival benefit was not demonstrated for patients who received postoperative radiation therapy versus surgery alone for pT2N0 oral cavity tongue cancer, irrespective of depth of tumor invasion.