Can magnetic resonance imaging be used to select patients for sentinel lymph node biopsy in prophylactic mastectomy?

BACKGROUND: Sentinel lymph node biopsy (SLNB) in the setting of prophylactic mastectomy (PM) remains controversial. In the current study, recent experience with PM was described and the value of preoperative magnetic resonance imaging (MRI) was analyzed in selecting patients for PM with or without SLNB.

METHODS: Between January 1999 and January 2006, 529 patients underwent 613 PMs. Both preoperative magnetic resonance imaging (MRI) and SLNB were performed selectively at the discretion of the surgeon.

RESULTS: Occult cancer was identified in 33 of 613 PMs (5%) (10 invasive and 23 ductal carcinoma in situ cases). PM with SLNB was performed in 393 of 529 patients (74%), 178 of whom underwent MRI. Of these, occult cancer was found in 6 of 178 patients (3%), all of whom had negative SLNB. Preoperative MRI was concordant with PM in 4 of 6 cases with occult carcinoma. The remaining 215 of 393 patients (55%) underwent PM with SLNB without MRI. Occult cancer was found in 18 of 215 patients (8%); 3 had positive SLNB. Overall, PM with SLNB spared 4 of 393 patients (1%) from axillary lymph node dissection (ALND). Among 136 patients undergoing PM alone, 57 had preoperative MRI. MRI detected 5 cancers and PM revealed an additional 4 occult carcinomas not detected by MRI. Overall, 9 of 136 patients (7%) undergoing PM alone were found to have occult cancer, 3 of which were invasive, raising the decision of reoperation with ALND.

CONCLUSIONS: Occult cancer was identified in 5% of PMs. PM with or without SLNB spared only 4 of 393 patients (1%) from undergoing ALND, whereas PM alone identified unsuspected invasive disease in 3 of 136 patients (2%). When performed, MRI accurately ruled out the presence of an invasive cancer in the prophylactic breast, suggesting that MRI can be used to select patients for PM without SLNB.