In the Era of PET Scans, Is Unilateral Radiation Therapy Enough to Treat Squamous Cell Carcinomas of the Head and Neck From an Unknown Primary?

Abstract

The goal of this study was to examine the effects of radiation treatment volume on overall survival and rates of recurrences among a population of head and neck cancer patient with unknown primaries at two different cancer institutes. Clinical characteristics were abstracted from the medical records of 62 patients with unknown primaries of the head and neck treated between 2000 and 2015 at Roswell Park Cancer Institute (Buffalo, NY, n = 33) and Upstate Medical University (Syracuse, NY, n = 29). Patients either received radiation therapy to one side of the head and neck, unilateral radiation (n = 34, RPCI = 28, Syracuse = 6), or radiation therapy to both sides of the head and neck, bilateral radiation (n = 28, RPCI = 5, Syracuse = 23). Mann Whitney U tests for ordinal data and χ2 and Fischer exact tests for categorical data were conducted to compare demographic and outcome factors between patients treated unilaterally and patients treated bilaterally. Overall survival (OS) and disease-free survival (DFS) trends for unilaterally and bilaterally treated patients were estimated using the Kaplan-Meier method. The effect of treatment volume on overall survival and disease-free survival was examined using multivariate Cox proportional hazard regression models. Models were adjusted for age and nodal stage. No significant differences in the frequency of local (P = .32), regional (P = .50), or distant (P = .76) failures were observed between patients treated unilaterally and those treated bilaterally. No significant differences were found in OS (3-year OS bilateral = 71.67%, unilateral = 77.90%, P =.503) or DFS (3-year DFS bilateral = 77.92%, unilateral = 69.43%, P = .626). Results from univariate (HR = 0.74, 95% CI 0.30, 1.80, P = .504) and multivariate analysis (HR = 0.74, 95% CI 0.31, 1.81, P = .511) for the effect of treatment volume on overall survival showed no significant difference in risk of mortality between the two treatment volumes. There was no statistically significant effect of treatment volume on disease free survival in both univariate (HR = 0.77, 95% CI 0.28, 2.18, P = .627) and multivariate (HR: 0.68, 95% CI 0.24, 1.93, P = .465) analyses. Unilateral radiation therapy is as effective in controlling disease as bilateral radiation therapy with similar overall survival in patients with squamous cell carcinomas of the head and neck from unknown primaries. In addition, unilateral radiation therapy may reduce acute and late toxicity effects of treatment as well as lower the risk of toxicity should a contralateral recurrence emerge.