The Association Between Use of Hypofractionated Radiation Therapy for the Treatment of Prostate Cancer and Treatment Completion

Abstract

While hypofractionated (HF) radiation therapy (RT) is recognized as a suitable treatment for low and intermediate risk prostate cancer, it is not yet the standard of care. As HF RT requires the patient to attend fewer appointments, it is potentially easier for patients to complete than conventional fractionation (CF) RT. Since noncompletion of RT has been shown to lead to inferior outcomes, use of HF RT may be a way to increase treatment adherence. This study examines whether there is a difference in treatment completion rates for HF RT versus CF RT in the context of prostate cancer.Radiation therapy order data from a prior authorization program and health plan claims data were extracted. The data related to patients belonging to commercial and Medicare Advantage health plans from a national organization. The patients included had early-stage prostate cancer, had not had prostatectomy, were not receiving palliative care, had no prior prostate cancer RT orders, and received their order for RT between July 1st, 2016 and September 30th, 2019. Orders were categorized as HF if they were authorized for 5 to 28 fractions of RT, and CF if they were authorized for 29 to 48 fractions. Each RT order was assigned a target date for completion, and completion was assessed on the basis of whether the patient had received the number of fractions authorized by that date. Patients with orders for 5 fractions were considered to have completed treatment if they received 3+ fractions, as these were stereotactic body RT regimens that are adjusted based upon treatment response. A Chi-square test was used to evaluate the association between the authorized regimen and completion. A multivariate logistic regression was used to assess the same, after controlling for age, urbanicity, the median income of the patient's home ZIP code, if the order was placed at a hospital, and if the ordering facility's name suggested an academic affiliation. Finally, a multivariate logistic regression was used to assess whether any of the control variables were associated with the authorization of a HF regimen.Of the 936 orders included, 309 (33.0%) were for HF and 627 (67.0%) were for CF. The completion rate significantly (P < 0.01) differed between the groups; 64.7% (200/309) for HF orders and 55.8% (350/627) for CF orders. Multivariate analysis found HF orders were significantly associated with treatment completion, relative to CF orders; 1.49 (95% CI: 1.12-1.99) adjusted odds. None of the other covariates were significantly associated with completion. Patients had significantly higher odds of having an order for HF if they came from a < $40,000 median income ZIP code (OR: 1.40; 95% CI: 1.01-1.93), or if the site of service at which the order was placed was a hospital (OR: 1.75; 95% CI: 1.26-2.42).Patients with orders for HF regimens completed their RT more frequently than patients with orders for CF regimens. The potential for greater treatment adherence should be considered as a possible benefit of HF.