Dose to Pharyngeal Constrictors and Esophagus Is Associated with Activity Decline during Concurrent Chemoradiation for Head and Neck Cancer

Abstract

While concurrent chemoradiation (CCRT) for head and neck cancer (HNC) has been successful in achieving high cure rates, it is often accompanied by significant morbidity and declining quality of life. In this study, we explore dosimetric predictors of activity decline in a cohort of patients who prospectively underwent activity monitoring during concurrent chemoradiotherapy for locally advanced cancers of the head and neck. We identified patients treated with CCRT for HNC from three prospective studies in which fitness trackers were used to measure step count. In each subject, we measured the mean dose delivered to organs at risk in the head and neck including the oral cavity, parotid glands, and pharyngeal constrictors and esophagus as one structure. Mean doses were compared to the percentage change in mean weekly step count. Linear regression was used to evaluate dosimetric data as a predictor of activity change. Fifty-five subjects met eligibility criteria. Nineteen subjects were treated for oropharyngeal cancer, 14 for laryngeal cancer, 8 for nasopharyngeal cancer, 6 for hypopharyngeal cancer, 6 for oral cavity cancer, and 2 for other cancers of the head and neck. Median age was 61 (interquartile range [IQR]: 51 to 66). Median daily step count average was 5,319 (IQR: 2,830 to 7,486) before starting chemoRT and fell to 3,798 (IQR: 2,321 to 5,107) five weeks into chemoRT. Median mean dose to the pharyngeal constrictors and esophagus was 45 Gy (IQR: 39 to 49 Gy). Mean dose to the pharyngeal constrictors and esophagus was associated with the rate of activity decline, with a 3.8% reduction in step count per week for every 10 Gy increase in mean dose (p=0.019, 95% CI: 0.6 to 7.0%). Mean dose to other structures evaluated did not significantly correlate with rate of activity decline. For a patient who averages 6,000 steps per day at baseline and is treated with a 7-week course of CCRT, the predicted daily step count post-treatment with a mean dose of 30 Gy to the pharyngeal constrictors and esophagus is approximately 2,600, compared to 1400 with a mean dose of 50 Gy. The mean dose to the pharyngeal constrictors and esophagus was associated with the rate of physical activity decline during CCRT for head and neck cancer. This data provides additional support that lowering mean dose to the pharyngeal constrictors and esophagus without compromising target volume coverage is key to minimizing treatment toxicities and improving tolerability of treatment.