Surgeon-associated variation in breast cancer staging with sentinel node biopsy

Background: Sentinel lymph node biopsy is the gold standard for axillary staging in early-stage, clinically node-negative breast cancer, so it is paramount that this operation be both precise and accurate, because excessive sentinel lymph node removal increases morbidity, whereas understaging risks inadequate treatment. The goal of this study was to assess surgeon variation in the number of sentinel lymph nodes removed and the oncologic yield of sentinel lymph node biopsy for breast cancer.

Methods: All patients in the Surveillance, Epidemiology, and End Results-Medicare database who underwent operative treatment for breast cancer from 2007-2011 were eligible for inclusion. Deidentified provider codes were used to track operations performed by individual surgeons. Only records in which an individual surgeon could be linked to a specific breast cancer operation were analyzed. The total number of sentinel lymph nodes removed and the number that were pathologically positive (oncologic yield) were recorded. Surgeon variation by T stage was analyzed using linear mixed-effects regression and logistic mixed-effects regression models.

Results: Query of the database identified 15,571 patients who met inclusion criteria, representing 2,478 providers. The mean number of sentinel lymph node procedures performed per provider per year was 1.3 (range 1-103). The lowest quartile of providers performed 1 or fewer sentinel lymph node procedures per year. The highest quartile of providers performed >8 sentinel lymph node procedures per year. The average number of sentinel lymph node removed per operation increased with increasing T stage for all providers (P < .001), including when N0 (P < .001) and node-positive (P = .003) patients were evaluated separately. There was surgeon-associated variation in the number of sentinel lymph node removed for each T stage (P < .001). In addition, there was surgeon-associated variation in the oncologic yield (sentinel lymph node positivity rate) by T stage (P < .001).

Conclusion: This study found surgeon-associated variation in axillary sentinel lymph node staging of breast cancer patients, which suggests the need to improve standardization of surgical practices to optimize the oncologic yield of these procedures and ensure accurate staging.