In a National Cancer Database analysis reported in JAMA Network Open, Patel et al found that treatment at facilities with high vs low radiation case volumes was associated with improved overall survival in men with node-positive prostate cancer receiving curative-intent external-beam radiation therapy and androgen-deprivation therapy.

As stated by the investigators, “Long-term control of node-positive (N1) prostate cancer, the incidence of which is increasing, is obtainable with aggressive treatment, and definitive external-beam radiation therapy with long-term androgen-deprivation therapy is an increasingly preferred option. Caring for these patients is complex and may require resources more readily available at high-volume centers.”

Study Details

The study involved data from 1,899 men diagnosed with T1 N1 M0 to T4 N1 M0 prostate cancer. Patients were treated with curative-intent external-beam radiation therapy and androgen-deprivation therapy between January 2004 and December 2016 at U.S. facilities reporting to the National Cancer Database.

Overall survival was compared for patients treated at centers with high vs low average cumulative facility volume (ACFV), defined as the total number of prostate radiation cases at the individual patient’s treatment facility from 2004 until the year of that patient’s diagnosis.

Key Findings

Median follow-up was 102.8 months. The median ACFV was 57.2 cases/yr (range = 2–651), with the optimal ACFV cutoff for high vs low volume being defined as 66.4 cases/yr. Overall, 1,114 patients (58.7%) were treated at low ACFV centers and 785 (41.3%) at high ACFV centers.

Median overall survival was 111.1 months (95% confidence interval [CI] =101.5–127.9 months) among men treated at high ACFV facilities vs 92.3 months (95% CI = 87.7–103.9 months) among those treated at low ACFV facilities (P = .01). Estimated 10-year overall survival was 44.7% (95% CI = 37.7%–51.6%) vs 35.6% (95% CI = 30.1%–41.1%).  After propensity score–based adjustment, weighted median overall survival was 111.1 months (95% CI = 101.5–127.9 months) vs 94.5 months (95% CI = 88.2–105.8 months; P = .04).

On multivariate analysis, treatment at a low vs high ACFV facility was associated with increased risk of death (hazard ratio [HR] =1.22, 95% CI = 1.02–1.46, P = .03). Treatment at a low ACFV facility was also associated with increased risk of death on multivariate analysis in the propensity score–weighted sample (adjusted HR = 1.20, 95% CI, 1.01–1.43; P = .04).

The investigators concluded: “This cohort study found a significant association of facility case volume with long-term outcomes in men with N1 prostate cancer undergoing external-beam radiation therapy with androgen-deprivation therapy. Specifically, treatment at a facility with high radiation case volume was independently associated with longer overall survival. Further studies should focus on identifying which factors unique to high-volume centers may be responsible for this benefit.”

Benjamin W. Fischer-Valuck, MD, of the Department of Radiation Oncology, Winship Cancer Institute at Emory University, is the corresponding author for the JAMA Network Open article.

Disclosure: The study was supported by the Breen Foundation, National Institutes of Health, National Cancer Institute, and Biostatistics and Bioinformatics Shared Resource of the Winship Cancer Institute. For full disclosures of the study authors, visit jamanetwork.com.