When is a lymph node dissection a lymph node dissection? the number of lymph nodes resected in sentinel and axillary lymph node dissections

Purpose: We sought to compare the number of lymph nodes (LN) resected in axillary lymph node dissections (ALND) and sentinel lymph node dissections (SLND), and to assess the validity of registry reporting for axillary staging in breast cancer. Methods: Women in the California Cancer Registry who underwent surgical axillary staging for T1/T2, M0 breast cancer between 2004 and 2008 were evaluated. The number of LN resected in patients reported as having SLND+ALND and ALND were assessed for compliance with 6 and 10 LN threshold definitions for ALND. The proportion of patients with ≤3 LN removed was assessed for patients receiving SLND only. Results: Of 71,907 patients, 45.5 % had SLND, 24.0 %, SLND+ALND, and 30.5 %, ALND. The median number of LN resected with SLND cases was 2 (range 1-41); SLND+ALND, 9 (range 1-63); and ALND, 11 (range 1-81) (p < 0.0001). Of patients undergoing ALND, 56.7 % had ≥10 LN removed; 46.2 % of patients with SLND+ALND had ≥10 LN removed (p < 0.0001). Overall, 75.5 % of patients with ALND had ≥6 LN removed and 67.8 % of patients with SLND+ALND had ≥6 LN removed (p < 0.0001). Of those receiving only SLND, 83.4 % had ≤3 LN removed. Conclusions: A significant proportion of patients did not meet the minimum LN count thresholds for full ALND or had excess LN removed in a SLND. Further investigation is required to determine whether absolute LN number or reported operative procedure and implied surgical technique better defines axillary staging in a registry database. © 2012 Society of Surgical Oncology.