Radiation therapy (RT) can be effective for managing patients with oligometastatic prostate cancer (OPCa), according to investigators at Johns Hopkins University School of Medicine in Baltimore.

A team led by Phuoc T. Tran, MD, PhD, based that conclusion on a study of 156 men with OPCa (median age 65.5 years) who underwent stereotactic ablative radiation (SABR) therapy to 354 metastatic lesions (54.2% in lymph nodes, 49.2% in bone, and 2.9% in visceral sites). Patients had a median follow-up of 24.6 months.

“This study represents, to the best of our knowledge, the largest single institutional series of men with OPCa treated with definitive intent RT to oligometastatic lesions,” Dr Tran’s team wrote in a paper published in the International Journal of Radiation Oncology Biology Physics.

At 24 months, the cumulative incidence of local failure was 7.4%. The median biochemical progression-free survival (bPFS) for the entire cohort was 12.9 months and 52% at 1 year, Dr Tran and colleagues reported. The time to the next intervention following SABR was 21.6 months.

Compared with men who had castration-resistant disease, those with hormone-sensitive disease had a significantly longer survival time (17.2 vs 7.2 months) and lower cumulative incidence of local failure at 24 months (4.8% vs 12.1%).

The investigators analyzed 28 men with hormone-sensitive disease treated with a course of peri-radiotherapy (RT) androgen deprivation therapy (ADT). All had recovery of testosterone after discontinuing ADT. After a median 33.5 months of follow-up, the median bPFS for the group had not been reached and the 24-month bPFS rate was 77%.

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On multivariate analysis, peri-RT ADT, smaller gross tumor volume, and hormone-sensitive disease were significantly associated with improved bPFS, according to the investigators.

“These findings appear to indicate the optimal time for intervention is with lower volume disease,” the authors wrote.

A total of 150 men had toxicity data available. Of these, 53 (35%) had acute grade 1 toxicity, 8 (5%) had grade 2, and none had grade 3 toxicity, Dr Tran’s team reported. Late toxicities developed in 13 patients (9%).

Reference

Deek MP, Yu C, Phillips R, et al. Radiotherapy in the definitive management of oligometastatic prostate cancer: The Johns Hopkins experience. Int J Radiat Oncol Biol Phys. 2019. doi: 10.1016/j.ijrobp.2019.08.008