Survival slightly higher at high-volume radiation treatment centers


Most readers will know by now that prostate cancer surgery results are significantly better at high-volume centers (see this link). Unsurprisingly, the same holds true for primary radiation treatment of high-risk patients.

Chen et al. analyzed the National Cancer Database (NCDB) to find data on 19,465 high-risk patients treated at 1,099 radiation facilities between 2004 and 2006 and followed up through 2012. Patient data included age, race, insurance status, co-morbidity, clinical stage, Gleason score, type of radiation, use of ADT, type of facility, household income, education level, and location.It should be noted, however, that the NCDB is a hospital-based cancer registry and so the NCDB includes only data from patients diagnosed and treated at Commission on Cancer accredited institutions; thus, the NCDB probably does not include data from large numbers of self-standing, physician-owned radiotherapy centers.

The 20 percent of radiotherapy facilities with the highest patient volumes treated half the patients, and that was arbitrarily chosen as the definition of “high volume.” After a median 81 months of follow-up, Chen et al. found that:

  • High-volume facilities treated an average (median) of 223 patients per year.
  • Low-volume facilities treated a median of 76 patients per year.
  • High-volume facilities were more likely to be
    • Associated with an academic medical center
    • Located in metropolitan areas.
  • Patients treated at high-volume facilities were
    • More likely to have higher Gleason scores, clinical stage T3, and lower PSA levels
    • Twice as likely to receive brachy boost therapy (17 vs. 8 percent).

“Brachy boost” therapy is the combined use of brachytherapy with a follow-up course of external beam radiation. The researchers adjusted for all relevant variations in patient data in their analysis.

Chen et al. were only able to retrieve data on overall mortality, not prostate cancer-specific mortality. The key finding was that for every additional 100 patients treated, mortality risk was reduced by 3 percent. So, a typical high-volume facility treating 223 patients over the study time period had 4.4 percent fewer deaths than a typical low-volume facility treating 76 patients.

Incidental findings of mortality risk included:

  • 33 percent lower risk among patients who received brachy boost therapy
  • 17 percent lower risk among patients who received brachytherapy
  • 5 percent increase in risk for every year of age
  • 30 percent lower risk among Hispanics compared to Caucasians or African Americans
  • 40 percent higher risk among those using Medicaid
  • Higher risk among those with incomes < $35,000 per annum and with less education
  • Higher risk among those with more co-morbidities, higher tumor stage, and higher Gleason scores

Unfortunately, there were no available data in this analysis on physician experience.

While the effect of treatment volume on overall mortality is small, it is statistically significant. What is most striking, however, is the overwhelming effects of age, poverty, and other risk factors. There is an important interaction effect as well: brachy boost therapy, which requires the coordination of various specialists, is often only available at high volume centers. As we’ve seen both here and in recent clinical trials, oncologic outcomes are significantly improved by the combination therapy.
Higher volume facilities tend to have the best equipment, attract the best doctors and have experienced treatment teams. However, the individual doctor’s experience and abilities is of much greater importance. With brachy boost therapy, it is not necessary that the external beam therapy and the brachytherapy be performed at the same facility, only that the radiation oncologists coordinate their treatments. Often, it is more convenient to travel to an experienced brachytherapist, but to have the time-consuming external beam portion of the treatment done locally. The patient should primarily find the most qualified doctor(s) for his treatment.

Editorial note: This commentary was written for The “New” Prostate Cancer InfoLink by Allen Edel.

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