David D Yang, Vinayak Muralidhar, Brandon A Mahal, Clair J Beard, Kent W Mouw, Neil E Martin, Peter F Orio, Martin T King, Paul L Nguyen

Following radical prostatectomy (RP), adjuvant radiation therapy (RT) decreases biochemical recurrence and potentially improves metastasis-free and overall survival for patients with high-risk pathologic features. Since adjuvant RT typically occurs daily over several weeks, the logistical challenges of extensive traveling may be a significant barrier to its use. We examined the association between distance to treatment facility and use of adjuvant RT. We identified 97,568 patients in the National Cancer Database diagnosed from 2004 through 2011 with cT1-4N0-xM0-x prostate cancer and found to have high-risk pathologic features (pT3-4 stage and/or positive surgical margins) at RP. Multivariable logistic regression adjusting for sociodemographic and clinicopathologic factors was used to examine the association between travel distance and receipt of adjuvant RT, defined as radiotherapy initiated within 12 months after RP. Overall, 10.6% (10,346) of the study cohort received adjuvant RT. On multivariable analysis, increasing travel distance was significantly associated with decreased use of adjuvant RT, with adjusted odds ratios of 1.0 (reference), 0.67, 0.46, 0.39, and 0.32 (all P<0.001) and prevalence of use at 12.6%, 8.8%, 6.3%, 4.9%, and 3.7% for patients living ≤25.0, 25.1 to 50.0, 50.1 to 75.0, 75.1 to 100.0, and >100.0 miles away, respectively. Increasing travel distance was strongly associated with decreased use of adjuvant RT in this national cohort of postprostatectomy patients with high-risk pathologic features. These results strongly suggest that the logistical challenges of extensive travel are a significant barrier to the use of adjuvant RT. Efforts aimed at improving access to radiotherapy and reducing treatment time are urgently needed.