Morbidity of sentinel node biopsy in breast cancer: the relationship between the number of excised lymph nodes and lymphedema.

BACKGROUND: Despite the reduced morbidity associated with sentinel lymph node biopsy (SLNB), lymphedema remains a clinically relevant complication. We hypothesized that a higher number of lymph nodes (LNs) removed during SLNB is associated with a higher risk of lymphedema.
METHODS: Six hundred patients with clinically node-negative breast cancer who underwent SLNB were prospectively studied. Circumferential bilateral upper extremity measurements were performed preoperatively and at 3-8 years after surgery. Association of lymphedema with total number of LNs excised and other clinicopathologic variables was analyzed by the Spearman rank correlation coefficient, Fisher's exact test, Wilcoxon rank sum test, and logistic regression.
RESULTS: At a median follow-up of 5 years, 5% of patients had developed lymphedema. Factors associated with lymphedema included weight and body mass index. There was no association between the number of LNs removed and the change in upper extremity measurements or in the incidence of lymphedema. Among patients with lymphedema (n = 31) compared to those without, the mean (3.9 vs. 4.2), median (4 vs. 3), and range (1-9 vs. 1-17) of number of LNs removed were similar (P = 0.93). Among the 33 women with ≥ 10 LNs removed, none developed lymphedema.
CONCLUSIONS: In this population of 600 women who underwent SLNB, there is no correlation between number of LNs removed and change in upper extremity circumference or incidence of lymphedema. These data suggest that other factors, such as the global disruption of the lymphatic channels during axillary lymph node dissection, play a larger role in development of lymphedema than does the number of LNs removed.