SAN FRANCISCO—In prostate cancer patients with postoperative high-risk features for biochemical failure following radical prostatectomy, whole pelvic radiotherapy may improve biochemical outcome, according to results of a study completed recently by Jae-Sung Kim, PhD, and colleagues.
The researchers presented results of their study during a poster session at the 2014 Genitourinary Cancers Symposium. The poster was titled Whole Pelvic Irradiation for Prostate Cancer Patients with a Biochemical Relapse following Radical Prostatectomy: The Era of Robot-Assisted Minimally Invasive Surgery.
The study period was August 2004 to April 2012. During that time, the researchers identified 180 patients who experienced biochemical failure following radical prostatectomy and who had been treated with salvage radiotherapy. The primary end point of the current study was biochemical relapse-free survival defined as no prostate-specific antigen (PSA) failure and no additional salvage treatments.
The 180 patients were stratified into three groups:
- prostate bed radiotherapy alone (n=52)
- prostate bed radiotherapy with hormone (n=85)
- whole pelvic radiotherapy with hormone (n=43)
The effects of whole pelvic radiotherapy combined with hormone were measured in high-risk patients defined as pN1 stage or inadequate pelvic lymph node dissection (harvested lymph nodes <4). When genitourinary or gastrointestinal (GI) adverse events occurred, the researchers noted toxicity from the treatment.
In the prostate bed radiotherapy alone group, the risk of biochemical failure following salvage radiotherapy was
Median follow-up was 43 months (range, 8-103 months). Independent predictors for poor biochemical relapse-free survival were time to PSA failure ≤1 year, PSA at salvage >1 ng/mL, PSA doubling time <6 months, and prostate bed radiotherapy alone.
In the prostate bed radiotherapy-alone group, the risk of biochemical failure following salvage radiotherapy was significantly higher compared with the whole pelvic radiotherapy with hormone group (HR = 3.9; 95% CI 1.8-8.3; p < 0.001). There were no statistically significant differences in outcomes between the prostate bed radiotherapy with hormone group and the whole pelvic radiotherapy with hormone group.
The benefit of whole pelvic radiotherapy with hormone over prostate bed radiotherapy alone was seen only in the high-risk patients (HR = 5.7; 95% CI 1.8-17.7; p = 0.003); there was no significant benefit seen in other patients.
Patients who received whole pelvic radiotherapy had more grade 2 or higher GI events compared with those who received prostate bed radiotherapy (17% vs. 5%; p = 0.01).
In summary, the researchers cautioned, “Patients with postoperative high risk features could benefit from whole pelvic radiotherapy and hormone therapy for postoperative biochemical failure. The additional toxicity by whole pelvic radiotherapy and long-term outcomes warrant further investigation.”
Source: Kim JS, Kang HC, Byun SS, et al. Whole pelvic irradiation for prostate cancer patients with a biochemical relapse following radical prostatectomy: the era of robot-assisted minimally invasive surgery. Abstract presented at 2014 Genitourinary Cancers Symposium, San Francisco, California. January 31, 2014.