Background: Regional lymph node dissection (RLND) is currently the most effective therapy for metastatic melanoma in groin lymph nodes. With thorough surgery, RLND lymph node (LN) retrieval numbers have a predictable distribution. Whether patients have inguinal or ilioinguinal dissection varies between institutions. This study was designed to provide LN retrieval parameters for inguinal and ilioinguinal LN dissections, and secondarily, to analyze known predictors for survival outcomes, including LN ratio, i.e., involved/total number LN removed.
Methods: A prospective database was used to identify 189 patients who had 200 groin dissections between July 2002 and February 2008 to derive parameters of LN retrieval. A subgroup of 177 patients who had one RLND was assessed for predictors of survival outcome.
Results: Inguinal dissection had median LN retrieval of 11 (interquartile range, 10-14); 8 LN or more were retrieved in 90% of cases, and 38% of cases had 10 LN or less. Ilioinguinal dissection had median LN retrieval of 21.5 (interquartile range, 17-25); 14 LN or more were retrieved in 90% of cases, and 0 cases had 10 LN or less. The strongest predictors of survival on multivariate analysis were LN ratio, macroscopic LN disease, and ulceration of the primary melanoma. Overall 39% of ilioinguinal dissections had positive pelvic LNs, but only 9.3% of those completed after positive sentinel node biopsy.
Conclusions: Thorough groin RLNDs have a predictable LN yield. LN ratio is the strongest predictor of outcome. Because pelvic LNs are frequently positive ilioinguinal dissection should be considered for all patients, especially those with macroscopic metastases to groin LNs.