Adjuvant Radiation Therapy Underused in High-Risk Prostate Cancer Patients
Patients who undergo radical prostatectomy for high-risk prostate cancer seldom receive adjuvant radiation therapy.
NEW ORLEANS—Patients who undergo radical prostatectomy for high-risk prostate cancer (PCa) seldom receive adjuvant radiation therapy (ART), despite evidence that it is associated with better outcomes, researchers reported at the 2015 American Urological Association annual meeting.
In a study of 105,226 men who underwent radical prostatectomy and had high-risk PCa features found on final pathology, only 7,741 (7.4%) received ART, according to a research team at the University of Chicago Medical Center led by Charles U. Nottingham, MD.
For the study, the investigators defined high-risk features as pT2 tumors with a positive surgical margin (PSM) or pT3 and pT4 tumors with or without a PSM. The study excluded patients with lymph node involvement and metastatic disease. They defined ART as receipt of radiation therapy within 6 months of surgery.
Younger age was among the significant predictors of ART receipt. Compared with patients younger than 65 years, those aged 65–75 and older than 75 years were 24% and 51% less likely to receive ART.
Other patient factors that significantly predicted receipt of ART included residing within the zip code of the treatment facility, surgery at a low-volume facility (50 cases or fewer per year), private insurance, a preoperative PSA level of 10 ng/mL or higher, a Gleason score of 7–10 at prostatectomy, and pT3 and pT4 cancers regardless of margin status.
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Compared with patients who had surgery at a facility in their zip code, patients who had surgery at a facility 61–120 miles and more than 120 miles away were 59% and 69% less likely to receive ART.
Compared with patients who had surgery at a facility that treats 50 or fewer prostatectomy cases per year (first quartile), those who had surgery at facilities in the second, third, and fourth quartiles were 43%, 58%, and 67% less likely to receive ART.
The lower use of ART at higher-volume centers may reflect a propensity to perform surveillance on high-risk patients and preferential treatment with salvage radiation therapy, Dr. Nottingham's team concluded.
Privately insured patients were 24% more likely to receive ART than uninsured patients. Patients with a preoperative PSA level of 10–20 and more than 20 ng/mL were 17% and 49% more likely to receive ART than those with a PSA level below 10 ng/mL.
Patients with a Gleason score of 7 and 8–10 were 1.8 and 4.7 times more likely to receive ART than those with a Gleason score of 6. Patients with pT3 or pT4 tumors with a negative surgical margin and those with pT3 or pT4 tumors with a PSM were 1.3 and 3.9 times more likely to undergo ART than patients with pT2 tumors with a PSM.