Association of Social-Ecological Factors With Delay in Time to Initiation of Postoperative Radiation Therapy: A Prospective Cohort Study.

Importance: Timely initiation of postoperative radiation therapy (PORT) is associated with reduced recurrence rates and improved overall survival in patients with head and neck squamous cell carcinoma (HNSCC). Measurement of the association of social-ecological variables with PORT delays is lacking. Objective: To assess individual and community-level factors associated with PORT delay among patients with HNSCC. Design, Setting, and Participants: This prospective cohort study carried out between September 2018 and June 2022 included adults with untreated HNSCC who were enrolled in a prospective registry at a single academic tertiary medical center. Demographic information and validated self-reported measures of health literacy were obtained at baseline visits. Clinical data were recorded, and participant addresses were used to calculate the area deprivation index (ADI), a measure of community-level social vulnerability. Participants receiving primary surgery and PORT were analyzed. Univariable and multivariable regression analysis was performed to identify risk factors for PORT delays. Exposures: Surgical treatment and PORT. Main Outcomes and Measures: The primary outcome was PORT initiation delay (>42 days from surgery). Risk of PORT initiation delay was evaluated using individual-level (demographic, health literacy, and clinical data) and community-level information (ADI and rural-urban continuum codes). Results: Of 171 patients, 104 patients (60.8%) had PORT delays. Mean (SD) age of participants was 61.0 (11.2) years, 161 were White (94.2%), and 105 were men (61.4%). Insurance was employer-based or public among 65 (38.5%) and 75 (44.4%) participants, respectively. Mean (SD) ADI (national percentile) was 60.2 (24.4), and 71 (41.8%) resided in rural communities. Tumor sites were most commonly oral cavity (123 [71.9%]), with 108 (63.5%) classified as stage 4 at presentation. On multivariable analysis, a model incorporating individual-level factors with health literacy in addition to community-level factors was most predictive of PORT delay (AOC= 0.78; R2, 0.18). Conclusions and Relevance: This cohort study provides a more comprehensive assessment of predictors of PORT delays that include health literacy and community-level measures. Predictive models that incorporate multilevel measures outperform models with individual-level factors alone and may guide precise interventions to decrease PORT delay for at-risk patients with HNSCC.