A large cohort study found that black women with early-stage invasive breast cancer were significantly less likely than white patients to undergo the less invasive axillary sentinel lymph node (SLN) biopsy. Black women also had a higher rate of lymphedema, due largely to that difference in treatment modalities.
“SLN is now a safe and integral part of the surgical management of early invasive breast cancer,” said Dalliah M. Black, MD, an assistant professor of surgical oncology at MD Anderson Cancer Center in Houston, in a press release. She presented the cohort study’s results earlier today at the San Antonio Breast Cancer Symposium (SABCS).
From an initial SEER/Medicare database cohort of 51,063 women with invasive breast cancer diagnosed between 2002 and 2007, researchers drew a final study cohort of 31,274 women. All patients had negative axillary lymph nodes on pathology and documented axillary surgical procedure. Of the total, 1,767 (5.7%) were black; 27,856 (89%) were white; and the remaining 1,651 (5.3%) were of other or unknown race.
Over the full study period, 62% of black patients and 74% of white patients underwent sentinel lymph node biopsy (P < .001). Both races saw an increase in the use of SLN over the course of the study, but the strong disparity persisted throughout; the procedure was an “acceptable alternative” in 2002, but became the preferred method for appropriate patients by 2007. At the end of the study, 83% of white patients and 70% of black patients were undergoing SLN biopsy.
The rate of lymphedema varied substantially based on which treatment was used. The five-year cumulative incidence of lymphedema was 12.1% for those undergoing axillary lymph node dissection (ALND) compared to 6.9% in those who underwent SLN biopsy. Among patients who did undergo biopsy, the risk of lymphedema was essentially the same, regardless of race. The cumulative incidence among black patients undergoing ALND was 18%, compared with 12.2% for white patients undergoing that procedure. Among those undergoing SLN biopsy, the rates were 8.8% for black patients and 6.8% for white patients.
Benjamin Smith, MD, an assistant professor at MD Anderson and the study’s senior author, said that “this ties the treatment disparity to a disparity in outcome.”
Dr. Black said the treatment disparity’s persistence even through 2007, when SLN biopsy had become the preferred treatment modality, surprised her and her team. She noted that data extending to more recent years is needed to further address the treatment disparity issue.
“Improving patient education and creating ways to ensure all healthcare providers know practice guidelines which they are able to implement, will help with this disparity,” Black said. “No early-stage, appropriate patient should opt for less if properly educated.”
The median age of women included in the study was 74 years. Three-quarters of patients had a tumor between 2 cm or smaller in size; 62% underwent a lumpectomy, and a total of 73% of the cohort did undergo a SLN biopsy.