Whole pelvis radiotherapy (WPRT) may improve treatment outcomes among patients with intermediate- or high-risk prostate cancer compared with prostate-only radiotherapy (PORT), a new study suggests.
A team led by Peter J. Hoskin, MD, PhD, of Southampton General Hospital in Southampton, UK, compared the approaches in a prospective cohort study that included 812 men with intermediate- or high-risk prostate cancer. All patients received external beam radiotherapy (EBRT) and high-dose-rate brachytherapy. Of the 812 men, 401 men received WPRT and 411 received PORT. The EBRT dose in the WPRT cohort was 46 Gy delivered in 23 fractions; the dose in the PORT group was 37.5 Gy delivered in 15 fractions.
After a median follow-up of 4.7 years, the biochemical progression-free survival (bPFS) rate was significant higher for WPRT than PORT recipients overall (89% vs 81%) and among patients with high-risk disease (84% vs 77%), Dr Hoskin and his collaborators reported in the International Journal of Radiation Oncology Biology Physics. The differences in bPFS between the groups remained significant after adjusting for Gleason score, presenting PSA level, T stage, and duration of androgen deprivation therapy. The study found no difference in overall survival.
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The authors noted that WPRT may improve outcomes by sterilization of micrometastatic pelvic nodal disease compared with PORT.
“With optimization of dose escalation to the prostate, prophylactic pelvic nodal irradiation in appropriately selected patients may be of clinical benefit,” the authors concluded.
The investigators reported low rates of post-treatment toxicities between the groups, with the rate of grade 3 or higher toxicities not exceeding 1.5% at any follow-up time point. WPRT, however, was associated with an increased prevalence and cumulative incidence of acute genitourinary and acute gastrointestinal toxicity. Dr Hoskin’s team observed no difference between the cohorts in late radiation toxicity.
Study inclusion criteria included the presence of stage T2c or higher disease and/or a Gleason score of 7 or higher and/or presenting PSA of 10 ng/mL or higher, and no evidence of nodal or other metastatic disease.
Reference
Tharmalingam H, Tsang Y, Choudhury A, et al. External beam radiotherapy (EBRT) and high-dose rate (HDR) brachytherapy for intermediate and high-risk prostate cancer: the impact of EBRT volume [published online October 11, 2019]. Int J Radiat Oncol Biol Phys.
doi: 10.1016/j.ijrobp.2019.09.044
