Timing of chemotherapy and radiation delivery for patients receiving chemoradiation for head and neck cancer: When does "concurrent" mean concurrent?

Purpose: To analyze practice patterns focusing on variations in the timing of chemotherapy relative to radiation in patients treated with concurrent chemoradiation for head and neck cancer. Methods and Materials: The medical records of 302 consecutive adult patients treated with concurrent chemoradiation for head and neck cancer between April 2014 and February 2022 were reviewed. After excluding 38 patients who received non-platinum-based regimens, induction chemotherapy, and/or had non-squamous cell histology, a total of 264 patients formed the primary population. To study the variability in which concurrent chemoradiation was delivered, descriptive statistics were used to determine the percentage of patients who deviated from starting chemotherapy and radiation on the same day. The chi-square statistic was used to compare differences in proportion among various subsets. A Cox proportional hazards model was then used to perform a multi-variate analysis to identify factors which independently influenced the likelihood for non-adeherence. Results: Among the 264 patients, a total of 187 patients (70.8%) had chemotherapy and radiation started on the same day with 171 of these (91.4%) receiving chemotherapy prior to radiation delivery. On multivariate analysis, both non-Caucasian ethnicity (OR: 1.13, 95% C.I. 1.01-1.20) and being non-English speaking (OR: 1.39; 95% C.I. 1.18-1.51) was significantly associated with greater likelihood of the receipt of radiation and chemotherapy on different days. Conclusion: Significant variation exists in the timing of chemotherapy relative to radiation for concurrent chemoradiation in the clinical setting. The potential repercussions on outcome warrante further invesigtation and are discussed.