Whole pelvic radiation therapy improves survival in high-risk prostate cancer

Prostate cancer (PCa) patients with higher lymph node (LN) risk scores and Gleason grade who are treated with whole pelvis radiotherapy (WPRT) have better overall survival (OS), reports a study.

“Men with unfavourable intermediate-risk (UIR-PCa) or high-risk PCa (HR-PCa) are often treated with definitive external beam radiotherapy (EBRT) plus androgen deprivation therapy,” the investigators said. “Treatment is frequently intensified by electively treating the pelvic LNs with WPRT, but practice patterns and the benefits of WPRT are not well defined.”

In this study, the investigators reviewed records of men diagnosed between 2008–2015 with UIR-PCa or HR-PCa and treated with prostate EBRT±androgen deprivation therapy (72–86.4 Gy) with (n=15,175) or without (n=13,549) WPRT from the National Cancer Database.

The Memorial Sloan Kettering Cancer Center nomogram was used to calculate the risk of LN involvement. Finally, the investigators balanced measured confounders with inverse probability of treatment weighting and generated OS hazard ratios (HRs) using multivariable Cox regression.

More than half of the men (53 percent) received WPRT. Every 1-percent increase in the risk of LN involvement was associated with a 1-percent increase in mortality risk (p<0.001).

WPRT appeared to lead to improvements in OS in all men with UIR-PCa and HR-PCa (HR, 0.95, 95 percent confidence interval [CI], 0.90‒1.006; p=0.055). In addition, WPRT was associated with improved OS in men with Gleason 9 and 10 disease (HR, 0.87, 95 percent CI, 0.78‒0.98; p=0.02) or risk of LN involvement ≥10 percent (HR, 0.93, 95 percent CI, 0.87–0.99; p=0.03).

“These results complement the recent POP-RT randomized trial in mostly positron emission tomography/computerized tomography-staged patients, demonstrating that a more heterogeneous population of men staged without functional imaging benefits from WPRT,” the investigators said.