Breast cancer treatment at high-volume centers is associated with an 11% reduction in overall mortality compared with lower-volume centers, according to study results published in the Annals of Surgery in February 2018. Although improved outcomes were seen for all stages, patients with stage 0-I, ER+/PR+, and ER+/PR- breast cancers received the most benefit.
With a cohort of more than 1 million patients, the study is the largest series to examine the effect of hospital volumes on patient outcomes in breast cancer. It is also the first to define case volume thresholds based on clinical outcome rather than arbitrary cutoffs.
These results can help patients with breast cancer decide where to undergo treatment, the authors noted. The American Society of Clinical Oncology and the American College of Surgeons Commission on Cancer currently recommend that women select a surgeon based on specialization and practitioner experience. The authors suggest that hospital case volume should also contribute to that decision.
“Regardless of patient age or tumor biology, all individuals with breast cancer benefit from receipt of treatment at high-volume centers, just like other less common malignancies,” says the study’s lead author, Rachel Greenup, MD, MPH, a breast cancer surgeon at Duke. “Case volume most likely reflects the subspecialty expertise and infrastructure required to deliver tailored contemporary breast cancer care.”
To examine the association between hospital volume and mortality, investigators queried the American College of Surgeons/American Cancer Society National Cancer Database. All patients between 18 and 90 years of age who were diagnosed with unilateral stage 0-III in situ or invasive breast cancer from 2004 to 2012 and treated with lumpectomy or unilateral or contralateral mastectomy were included in the analysis.
Investigators used restricted cubic spline analysis to create 3 hospital volume groups: low volume
(< 148 cases/year; 51.3% of patients), moderate volume (148-298 cases/year; 30.8% of patients), and high volume (> 298 cases/year; 17.9% of patients). Collected covariates included age at diagnosis, gender, race/ethnicity, income level, insurance status, and hospital type, among others.
Rates of lumpectomy, unilateral mastectomy, chemotherapy, endocrine therapy, and radiation therapy were similar between groups. And, although contralateral mastectomy was also slightly increased at higher-volume centers, studies have shown that this approach does not affect survival. It is more likely, the authors argued, that volume in breast cancer is a proxy for the subspecialty infrastructure required for excellence in multidisciplinary oncology care.