Selective use of sentinel lymph node surgery during prophylactic mastectomy

BACKGROUND. Patients with invasive cancer identified at the time of prophylactic mastectomy (PM) will require axillary lymph node dissection for staging; therefore, many surgeons advocate sentinel lymph node (SLN) surgery at the time of PM. The current study investigates the invasive cancer rate in PM and evaluates factors associated with invasive cancer to guide SLN surgery use. METHODS. Patients undergoing PM at the M. D. Anderson Cancer Center between January 2000 and July 2005 were identified from a prospective database. Clinical, radiographic, and pathologic data were collected. RESULTS. A total of 409 patients (436 PM cases) were identified; 382 underwent contralateral PM (CPM) and 27 underwent bilateral PM (BPM). Cancer was identified in 22 of 436 PM cases (5%). Of these, 14 patients (64%) had ductal carcinoma in situ (DCIS). Only 8 patients (1.8%) had invasive cancer, with a mean tumor size of 5 mm (range, 2-9 mm). There was no difference in the occult cancer rate between CPM and BPM. No cases of invasive cancer were identified in the 23 patients with BRCA mutations. Significantly increased risk of invasive cancer in the PM breast was seen in postmenopausal patients (3.7%; P = .007), patients age > 60 years (7.5%; P = .008), and patients with history of invasive lobular carcinoma (9.7%; P = .0002) or lobular carcinoma in situ (LCIS) (7.7%; P = .008). CONCLUSIONS. The frequency of cancer in PM is very low and the majority represents DCIS. Therefore, routine use of SLN surgery in all patients undergoing PM is not warranted. However, patients at higher risk for whom SLN surgery should be considered include older women and patients with a history of lobular cancer or LCIS.