Melaku A Arega, David D Yang, Trevor J Royce, Brandon A Mahal, Edward Christopher Dee, Santino S Butler, Sybil Sha, Kent W Mouw, Paul L Nguyen, Vinayak Muralidhar

Following radical prostatectomy, men with adverse pathologic features or a persistent post-operative detectable PSA are candidates for postoperative radiation therapy (PORT). Previous data have suggested disparities in receipt of adjuvant radiation therapy for adverse pathologic features according to travel distance. Among patients without adverse pathologic features (pT2 disease and negative margins), the main indication for PORT is a persistent post-operative detectable PSA. However, it remains unknown whether the rate of receipt of PORT in this cohort of men with persistently detectable PSA is related to travel distance from the treating facility. Using the National Cancer Database, we identified 170,379 men with prostate cancer diagnosed in 2004-2015 managed with upfront surgery who were found to have pT2 disease with negative surgical margins. Multivariable logistic regression defined adjusted odds ratios (AORs) with 95% confidence intervals (95CI) of receiving PORT as the primary dependent variable and distance (< 5, 5-10, 10-20, > 20 miles from the treatment facility) as the primary independent variable. Within our cohort, progressively farther distance from the treatment facility was associated with lower rates of PORT. In patients living <5 miles, 5-10 miles, 10-20 miles, and >20 miles from the treating facility, rates of PORT of were 1.37% (referent), 1.16% (AOR 0.90, 95CI 0.79-1.04, p=0.158), 0.98% (AOR 0.80, 95CI 0.70-0.93, p=0.003), and 0.64% (AOR 0.47, 95CI 0.41-0.54, p<0.001) respectively CONCLUSIONS: For men with localized prostate cancer without adverse pathologic features managed with surgery, increasing distance from treatment facility was associated with lower receipt of PORT. Given that the rate of a persistent post-operative detectable PSA is unlikely to depend on the distance to the treatment facility, these findings raise the possibility that the geographic availability of radiation treatment facilities influences the decision to undergo PORT for patients with persistent post-operative detectable PSA.