Assessing BF in Patients With Prostate Cancer Treated With Radiation

The risk of biochemical failure (BF) increases over time for patients with prostate cancer (PCa) initially treated with radiation (RT), according to a study presented at the 2022 American Society for Radiation Oncology Annual Meeting Annual Meeting.

In this study, presenting author Gregory S. Alexander, MD, and colleagues assessed 2591 patients with low- or intermediate-risk PCa enrolled in the Radiation Therapy Oncology Group (RTOG) 0126 or 0415 or treated with RT alone. They estimated overall survival using Kaplan-Meier analysis at different survival points. The investigators assessed BF rates using cumulative incidence and used multivariable Cox proportional hazards modeling (MVA) to analyze for risk of the following factors: Gleason score (GS), T stage, prostate-specific antigen (PSA), and dose equivalent of 2 Gy per fraction (EQD2) of prescribed dose.

Following analysis, the results showed that the 3-, 5-, and 8-year rates of BF from time of treatment were 7.1%, 12.5%, and 22.3%, respectively. Among patients surviving 1, 3, and 5 years without BF, the rates of BF in the next 5 years were 14.2%, 17.2%, and 18.8%, respectively. The results of MVA showed that GS 7 (hazard ratio [HR], 1.907; P<.001), T2 disease (HR, 1.375; P<.001), and increasing PSA (HR, 1.114; P<.001) were markedly correlated with an augmented risk of BF, whereas increasing EQD2 was associated with decreased BF rates (HR, 0.922; P<.001). The researchers further observed that for patients who survived 5 years without BF, all baseline prognostic factors remained statistically significant, including GS 7 (HR, 2.401; P<.001), stage T2 (HR, 1.344; P=.0396), PSA (HR, 1.109; P<.001), and EQD2 (HR, 0.887; P<.001).

“Conditional risk of BF increases over time for patients with PCa initially treated with RT. Initial biologic and treatment variables remain prognostic at long-term follow-up, with dose-escalated RT continuing to be associated with decreased BF,” the researchers concluded. “This data can be used to counsel patients for their risk of BF in follow-up and to help decide on the frequency of PSA monitoring.”

Source: Alexander GS, Krc RF, Assif JW, et al. Conditional survival of patients with prostate cancer undergoing external-beam radiotherapy on RTOG 0126 and 0415. Abstract 1003. Presented at the 2022 ASTRO Annual Meeting; October 23-26, 2022; San Antonio, TX.