Analysis of Skin Flap Thickness and Residual Breast Tissue After Mastectomy.

PURPOSE: Residual breast tissue (RBT) after mastectomy represents an unknown risk for local recurrence or development of a new cancer and affects decisions regarding adjuvant radiation therapy. This study used breast magnetic resonance imaging to evaluate the frequency of RBT and provide average thickness skin flap measurements in patients with total mastectomy, skin-sparing mastectomy, and nipple-sparing mastectomy (NSM) followed by breast reconstruction.

METHODS AND MATERIALS: We carried out a retrospective analysis of 7432 consecutive postoperative breast magnetic resonance imaging examinations performed between August 2008 and July 2013, selecting 367 women (mean ± standard deviation age, 46.7 ± 8.7 years) who had undergone therapeutic or prophylactic mastectomy with reconstruction, for a total of 501 cases. The variables analyzed included fibroglandular tissue presence, skin flap thickness at 11 pre-established points, age, weight, height, body mass index, laterality, surgical indication, surgery type, reconstruction type, adjuvant therapy, and cancer treatment history. Statistical analyses were descriptive and comparative and included logistic regression models (P < .05).

RESULTS: At 9 of the 11 points of measure, the median thickness of the flap exceeded 5.5 mm. Excluding the areolar region, RBT was identified in 29.9% of the cases: 21.3% of the therapeutic mastectomy cases and 51% of the NSM cases. The variables independently associated with the presence of RBT were flap thickness (P < .001), patient height (P < .03), mastectomy indication (P < .001), mastectomy type (P < .012 for skin-sparing mastectomy and P < .001 for NSM and total mastectomy), and breast reconstruction with flap (P < .019).

CONCLUSIONS: All forms of mastectomy leave RBT. Our study has demonstrated that the RBT amount can be variable and quite prevalent. Because of the low quality of the evidence to ensure the oncological safety of sparing mastectomies, we suggest that knowledge of the extent of the remaining breast tissue is important for guiding additional surveillance and therapeutic interventions, including radiation therapy.