Decision analysis to assess the efficacy of routine sentinel lymphadenectomy in patients undergoing prophylactic mastectomy

BACKGROUND. Patients who have invasive breast cancer identified after prophylactic mastectomy (PM) require axillary lymph node dissection (ALND) for lymph node staging (ie, directed ALND). Because the majority of these patients will be lymph node negative, sentinel lymphadenectomy (SLND) has been advocated at the time of PM to avoid the sequelae of unnecessary ALND. The objective of this study was to compare the efficacy of 2 surgical strategies, routine SLND versus directed ALND, in PM patients. METHODS. A decision-analytic model was created to compare the 2 surgical strategies. Model estimates were derived from a systematic literature review. The endpoints that were examined to compare the 2 strategies were the number of SLNDs performed per breast cancer detected, the number of SLNDs attempted to avoid 1 ALND in a lymph node-negative patient with occult invasive cancer, and the number of axillary complications associated with each strategy. RESULTS. The prevalence of invasive cancer in patients undergoing PM was estimated at 1.9%. At this rate, 37 SLNDs were performed per 1 breast cancer detected, and 73 SLNDs were required to avoid 1 ALND in a lymph node-negative PM patient. In 1 model scenario, the probability of complications per breast cancer detected was 9-fold greater with the SLND strategy than with the directed ALND strategy (2.7 vs 0.3). The complication rates for the 2 strategies become equivalent in the model scenario when the prevalence of occult invasive cancer was projected to 28%. CONCLUSIONS. Routine SLND for patients undergoing PM is not warranted given the large number of procedures required to benefit 1 patient and the potential complications associated with performing SLND in all patients.