Radiation center volume linked to prostate Ca outcomes

Prostate cancer patients treated at radiation facilities with higher prostate cancer radiation volumes tend to have better overall survival than those treated at lower volume radiation centers, according to a new study.

“Our paper shows that experience counts," said senior author Paul Nguyen, MD, of Brigham and Women's Hospital, Boston, in a press release from that institution.

Researchers analyzed data from 19,565 high-risk prostate cancer patients treated with radiation at 1,099 facilities. Among their findings: Men treated at facilities seeing more than 43 patients annually, which are centers in the top 20% by prostate radiation volume, had 76% 7-year overall survival, versus 74% 7-year overall survival for men treated at facilities in the bottom 80% of volume. This association remained significant when radiation case volume was dichotomized at 37 patients per year (or the 75th percentile), 60 patients per year (90th percentile), and 84 patients per year (95th percentile), but not the 50th percentile, with 19 patients per year, according to the paper, which was published in the International Journal of Radiation Oncology • Biology • Physics (2016; 94:683-90).

Adam S. Kibel, MD, who was not involved with the study, told Urology Times that a 2% improvement in survival at 7 years is fairly striking, “particularly if the only thing you have to change is volume.”

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“We spend hundreds if not millions of dollars per year on novel treatments to improve survival for cancer patients. This is a fairly easy, low-cost way to improve outcomes,” said Dr. Kibel, of Brigham and Women’s Hospital.

Next: Concept of specific associations between volume and radiation novel

The concept that volume is associated with outcomes is well established, according to Dr. Kibel, but the specific associations between volume and radiation for prostate cancer is more novel.

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“Radiation therapy is fairly standard across all centers. The differences between a low-volume and high-volume center are going to be small. So, what is particularly interesting about this finding is that these small differences do translate to an improved outcome for patients. This illustrates the well-known phrase that practice makes perfect. It also suggests that the observed improvement is likely due to small changes in treatment, which add up to a positive impact on patients’ outcomes,” Dr. Kibel said.

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Not only do radiation oncologists at high-volume centers have more experience, but the multidisciplinary team, including urologists, medical oncologists, radiologists, and pathologists, also have more expertise in making accurate diagnoses and tailoring systemic therapy regimens to ensure optimal patient outcomes, according to Dr. Nguyen.

Next: Findings give urologists a reason to consider volume at radiation centers they use

The new findings give urologists a reason to consider volume at the radiation centers they use, Dr. Kibel said.

“Radiation, just like surgery, is not something to dabble in,” Dr. Kibel said. “The findings suggest that a particularly low-volume center should probably be avoided.”

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The question about why the association exists remains, but Dr. Kibel has a theory.

“The question is always, why? Is it due to volume per se; ie, if you do more, you just get technically better? Or could it be that the radiation oncologist at higher volume centers are more specialized, so they understand the nuances of the treatment better?  Or is it something completely different about the center itself?” Dr. Kibel said.

“I believe that patients with access to a team of clinicians that includes urologists, radiation oncologists, and medical oncologists are often guided to better treatment options. So, it may be that it is not necessarily the treatment that is better at a higher volume facility, but rather that the patient selection is better.”

More on Prostate Cancer:

ASCO endorses prostate Ca active surveillance guideline

Utility of PCa markers in African-Americans differs

Surveillance: Reclassification risk drops after 2 years

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