Trends of Adjuvant Radiation After TORS in Clinically Node Negative Oropharyngeal Cancer.

OBJECTIVE

Frequency of adjuvant treatment for clinically node negative (cN0) oropharyngeal cancer (OPC) patients, candidates for single modality treatment, is not well established. We aimed to determine the rate and clinical predictors of adjuvant radiation therapy (aRT) among cT1-T2 N0 patients undergoing transoral robotic surgery (TORS).

METHODS

The National Cancer Database was retrospectively reviewed for cT1-T2 N0 OPC patients who received TORS as definitive treatment between 2010 and 2017. Demographic, oncologic data, and the proportion of patients receiving aRT were collected. Multivariable logistic regression was performed to determine clinical predictors of aRT. Adjusted Odds Ratios (aOR) with 95% Confidence Intervals (95% CI) were calculated.

RESULTS

1173 cN0 OPC patients underwent TORS (mean age 62 ± 9 years). 95% of patients were pT1-T2 and 59% were pN0. Overall, 29% of patients received aRT, including 21% of cT1 patients and 37% of cT2 patients. 32% of patients with tonsil/lateral pharyngeal wall and 29% with base of tongue tumors received aRT. Among those with negative margins, 25% received aRT. Positive margins (aOR 4.0, 95% CI 2.7-5.8), base of tongue subsite (aOR 2.7, 95% CI 1.5-4.7), and salivary gland malignancies (aOR 2.9, 95% CI 1.6-5.3) had an increased likelihood of adjuvant RT. Compared to pT1 patients, pT2 was associated with receiving adjuvant RT (aOR 1.9, 95% CI 1.4-2.6). HPV status was not a significant predictor of aRT.

CONCLUSION

Nationally, most cT1-T2 N0 OPC patients undergoing TORS ultimately do not receive adjuvant radiation therapy, thus representing excellent candidates for single-modality treatment in most cases.

LEVEL OF EVIDENCE: N/A.