Prostate cancer (PCa) patients experience better survival when they are treated at high-volume radiation centers, a new study finds.
“The primary implication of our study is that similar to patients seeking the best surgical outcomes, patients seeking the best radiation outcomes should also seek out facilities that treat a high volume of patients with radiation,” Paul L. Nguyen, MD, of Dana-Farber Cancer Institute and Brigham and Women’s Hospital in Boston, and colleagues wrote in International Journal of Radiation Oncology.
To determine whether a volume effect existed for radiation treatment of PCa, the investigators used the National Cancer database, a nationwide hospital-based database capturing 70% of newly diagnosed PCa cases. They identified 19,565 high-risk patients with non-metastatic PCa and followed them for a median of 81 months to see if there was a difference in overall survival. Patients received external beam radiation therapy (EBRT) and/or brachytherapy during 2004-2006; the researchers did not examine other forms of radiation.
After analyzing the radiation case volume of each hospital, the investigators discovered that each increment of 100 radiation-treated patients was associated with a 3% increase in overall survival. They adjusted results for known confounders, such as radiation type, use of androgen deprivation therapy (ADT), tumor stage, insurance status, and co-morbidities.
The top 20% of facilities treated half of PCa patients. Using the 80th percentile of case volume as the cutoff, Dr. Nguyen’s team found that high-volume radiation centers (43 patients/year) were associated with improved survival (7-year overall survival 76% vs. 74%). When they tested other cutoffs, the association remained significant. High-volume radiation centers tended to be academic hospitals located in metropolitan areas.
Researchers have noted a so-called “volume effect” for PCa surgery and with other types of cancers. Dr. Nguyen and his colleagues cited several possible reasons for a similar effect for radiation treatment of PCa. First, the quality of radiation treatment may be greater at high-volume centers. The health care team may be more experienced at selecting the right targets for radiation and may feel more comfortable delivering higher doses; for example, these centers were more likely to use combined EBRT and brachytherapy. Second, these centers may have experts from multiple disciplines on site, allowing for greater collaboration and consistency of care; for example, the optimal staging and duration of ADT.
The study examined overall rather than cancer-specific survival, so it remains possible that healthier patients sought treatment at high-volume facilities. The investigators also were unable to determine the duration of ADT.