Obesity influences outcome of sentinel lymph node biopsy in early-stage breast cancer

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Abstract
Background: Sentinel lymph node biopsy is a rapidly emerging standard of care for staging the axilla in invasive breast cancer. Factors influencing success must be identified to understand the procedure's limitations and challenges. Increasing body mass with age has an inverse relationship to success. A proportion of SLN biopsy patients are both senior and overweight, so measurement of the body mass to age relationship is essential. Study design: We reviewed mapping successes and failures in 2,495 SLN biopsy procedures performed between September 1996 and June 2001. Clinical stage T1 N0 to T3 N0 breast cancer cases were included. We used a combined technique (radioisotope and blue dye) to detect SLNs. Failure was defined as the inability to identify any nodes with either blue dye or by in vivo counts. Body- mass index (BMI) for each patient was measured by height and weight data (kg/m2), and cases were stratified by BMI and age. Results: Among 2,495 cases, there were 62 failed and 2,433 successful mappings (failure rate = 2.48%). Mean age, weight, and BMI were significantly higher in the failure group. The success of SLN biopsy was inversely related to BMI (r = −0.98, p = 0.002). When stratified by patient age (< 50 versus ≥50 years), this relationship was more pronounced in the ≥ 50 group. Multivariate analysis of age, weight, and BMI found age (p = 0.011) and BMI (p = 0.00001) to be predictive of SLN mapping success, with weight alone not significant. Conclusions: Increasing age and BMI do not appear to be contraindications for SLN biopsy. Rather, surgeons should be aware that increasing body mass and age are potential risk factors for a failed procedure, in which case a completion axillary node dissection for staging is required.