The rate of sentinel lymph node dissection as the standard of care for node-negative breast cancer has persistently trailed among black women, with negative clinical consequences as the result.
Use remained roughly 12 to 14 percentage points lower than among white women throughout the period from 2002 through 2007 as the procedure became established as preferred over completion axillary node dissection, Dalliah M. Black MD, of the University of Texas MD Anderson Cancer Center in Houston, and colleagues found.
The disparity was independent of patient age, tumor characteristics, type of tumor surgery, and other factors in the study of the linked Surveillance, Epidemiology, and End Results (SEER) and Medicare databases.
It was also associated with a doubling in lymphedema risk, the group reported here at the San Antonio Breast Cancer Symposium.
The sentinel lymph node is the first node said to be “standing guard” for your breast. In sentinel lymph node dissection, the surgeon looks for the very first lymph node that filters fluid draining away from the area of the breast that contained the breast cancer. If cancer cells are breaking away from the tumor and traveling away from your breast via the lymph system, the sentinel lymph node is more likely than other lymph nodes to contain cancer.
The idea behind sentinel node dissection is to spare women more invasive surgeries and their lingering side effects.
In the procedure, the surgeon would remove ten or more lymph nodes and analyze all of them to look for cancer, while removing only the one node that is most likely to have it. If this node is clean, chances are the other nodes have not been affected. In reality, the surgeon usually removes a cluster of two or three nodes—the sentinel node and those closest to it.
Studies have shown that after almost five years, women who had just the sentinel node removed were as likely to be alive and free of cancer as women who had more lymph nodes removed.
Although the retrospective claims data didn’t provide an explanation, Black suggested that socio-economic factors may be playing a dominant role in explaining why the alternative to axillary node dissection is less common among African-American women. Axillary node dissections often lead to full mastectomies with women with more invasive breast cancers.
“Patients who are from regions of lower income, lower education, and patients from regions with lower surgeon density were less likely to have a sentinel node biopsy; so there probably are some socio-economic things,” she told MedPage Today, referring to preliminary data from an analysis not reported at the session.
Race may be just a surrogate for socio-economic factors, suggested Clifford A. Hudis, MD, chief of the breast cancer medicine service at Memorial Sloan-Kettering Cancer Center in New York City.
“This is one of many studies that show an association between socio-economics and access to care, and sometimes quality of care and outcomes,” he said in an interview.
Since no clear solution has appeared, there’s no reason to suspect that the disparity would have disappeared since 2007, Hudis noted.
“It is an issue, but I don’t know what the take home is other than it’s bad to be poor,” he concluded.
Black’s group examined a cohort of 31,274 women in the SEER/Medicare database diagnosed with non-metastatic, invasive breast cancer from 2002 through 2007 who had pathologic negative axillary lymph nodes and an axillary node surgical procedure documented in Medicare claims.
The overall rate of sentinel lymph node dissection was 62 percent among black patients, 65 percent among other non-white patients, and 74 percent among white patients.
Use increased over the study period for both black and white patients from 2002 when sentinel lymph node biopsy for axillary staging was first suggested as an alternative in stage I or II breast cancer by the National Comprehensive Cancer Network (NCCN) and American Society of Breast Surgeons.
By 2007, when it was recommended as preferred in the NCCN guidelines, the rates reached 83 percent among white patients and compared with 70 percent among black patients.
Rates persistently showed a two- to three-year lag for the black patients.
Black women’s 33 percent lower likelihood of sentinel lymph node biopsy after adjustment for other factors was nearly identical in sensitivity analyses looking only at those who got mastectomy and only those who got lumpectomy.
That disparity had an impact on five-year cumulative lymphedema incidence. Rates were:
- 18 percent among black women who got completion axillary lymph node dissection
- 12.2 percent among white women who got completion axillary lymph node dissection
- 8.8 percent among black women who got sentinel lymph node dissection
- 6.8 percent among white women who got sentinel lymph node dissection
Since lymphedema risk in black patients who had sentinel node biopsy was in the seven percent to nine-percent range like that of white patients, “this suggests that when black patients had the appropriate surgery they were not at an increased risk of lymphedema,” Black told attendees.
Axillary dissection and black race both independently predicted elevated lymphedema risk.