Surgeon Experience Affects Likelihood of Sentinel Lymph Node Biopsy in Older Women With Breast Cancer
Sentinel lymph node biopsy is standard of care for axillary staging in clinically node-negative breast cancer, and underuse of sentinel lymph node biopsy could be associated with unnecessary axillary lymph node dissection and lymphedema. In a study reported in JAMA Surgery, Yen et al assessed the impact of a surgeon's volume and percentage of cases involving breast cancer on use of sentinel lymph node biopsy in older women with invasive breast cancer. They found that younger patients and those who are treated by surgeons with higher volume and greater concentration of breast cancer cases are more likely to receive sentinel lymph node biopsy.
Study Details
This population-based prospective cohort study, conducted in California, Florida, and Illinois, included 1,703 women aged 65 to 89 years identified from Medicare claims as having had incident invasive breast cancer surgery in 2003. Surgery was performed by 863 surgeons. The percentage of operations performed for breast cancer and annual volume of breast cancer cases for surgeons were determined from Medicare claims.
Patients had a mean age of 73 years, 91% were white, 63% had a National Cancer Institute combined comorbidity score of 0, 70% had stage T1 tumors and 19% had T2 tumors, 21% had lymph node involvement, and 62.5% underwent breast-conserving surgery and 37.5% underwent mastectomy.
Among surgeons, the median annual Medicare volume of breast cancer cases was 6.0 (range, 1.5–57) and the median percentage of breast cancer cases was 4.5% (range, 0.4%–100%). Overall, breast cancer accounted for ≥ 10% of operations for 21% of surgeons, and 24% of surgeons had ≥ 12 breast cancer cases per year, including 55% of surgeons with ≥ 10% breast cancer concentration. Surgeons with the higher percentage of breast cancer operations were more likely to be female, to be a surgical oncologist, to be a member of the American Society of Breast Surgeons or Society of Surgical Oncology, and to have an academic affiliation.
Predictors of Sentinel Lymph Node Biopsy
Of the 1,703 women, 56% received an initial sentinel lymph node biopsy, 37% initial axillary lymph node dissection, and 6% no axillary surgery. Multivariate analysis including the 1,585 women who underwent axillary surgery (60% sentinel lymph node biopsy, 40% axillary lymph node dissection) and adjusting for comorbidity, body mass index, and geographic location showed that women undergoing surgery by members of the American Society of Breast Surgeons (odds ratio [OR] = 1.98, P < .001) or Society of Surgical Oncology (OR = 1.59, P = .02) were significantly more likely to receive sentinel lymph node biopsy.
There was no significant interaction between society memberships (P = .92), indicating that the effects of membership were additive. The odds ratio for sentinel lymph node biopsy among women undergoing surgery by surgeons who were members of both societies was 3.14 (95% confidence interval [CI] = 2.02-4.87).
Patient age was also a significant predictor of sentinel lymph node biopsy, with patients aged 70 to 74 years (OR = 0.70), 75 to 79 years (OR = 0.87), and ≥ 80 years (OR = 0.50) being significantly less likely to undergo the procedure compared with those aged 65 to 69 years (P < .001 for trend). Surgeon years since graduation from medical school was not a significant predictor of procedure.
Interaction of Volume and Concentration
The likelihood of sentinel lymph node biopsy increased with both higher surgeon breast cancer volume and higher percentage of breast cancer cases. However, these effects were not additive, as indicated by a significant interaction between the two (P < .001) on multivariate analysis. Using the odds ratio for sentinel lymph node biopsy for a surgeon with a volume of six breast cancer surgeries per year and a concentration of 3% as a reference value, odds ratios for identical concentration percentages (eg, 5%, 10%, 15%, or 20%) increased with increasing surgeon volume up to the highest level of surgeon volume (eg, 24 cases per year), at which point there were no differences according to concentration percentages.
Similarly, odds ratios increased as surgeon volume increased from 6 to 12 and 24 cases per year. However, as surgeon concentration percentage increased, the effect of surgeon volume on odds ratio decreased, such that at surgeon concentration of 30% (4% of the study surgeons), the incremental effect of surgeon volume was negligible.
Overall, the likelihood of sentinel lymph node biopsy increased significantly from an odds ratio of 1.05 (95% CI = 1.02–1.09) for surgeon concentration of 5% to 1.96 (95% CI = 1.03–3.05) for concentration of 30%. At a volume of 12 breast cancer cases annually, the odds ratio for sentinel lymph node biopsy ranged from 1.40 (95% CI = 1.25–1.56) to 2.09 (95% CI = 1.44–3.05) as surgeon concentration increased from 5% to 30%.
The investigators concluded: “Patients who receive treatment from surgeons with more experience with and focus on breast cancer are significantly more likely to undergo [sentinel lymph node biopsy], highlighting the importance of receiving initial treatment by specialized providers. Factors relating to specialization in a particular area, including our novel surgeon percentage measure, require further investigation as potential indicators of quality of care.”
Tina W. F. Yen, MD, MS, of Medical College of Wisconsin, is the corresponding author for the JAMA Surgery article.
The study was supported by grants from the National Cancer Institute.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
