Extreme Oncoplasty: Oncologically Safe When Compared with Mastectomy.

Background: Extreme oncoplasty is a breast-conserving operation using oncoplastic techniques in a patient who does not meet the traditional criteria for breast conservation and in whom most physicians would suggest a mastectomy. These tumors are generally multicentric and/or multifocal, they span more than 50 mm, or they can be large recurrences in a previously irradiated breast.

Methods: A prospective single institution database was queried from 2008 through mid 2023 for patients who met the criteria for extreme oncoplasty and were treated with excision plus whole-breast radiation therapy (WBRT) or mastectomy without WBRT. Patients with recurrent breast cancer were excluded. Endpoints were local, regional, and distant recurrence as well as overall and breast-cancer-specific survival.

Results: 272 patients were treated with oncoplastic mammaplasty, using a standard or split reduction excision followed by postoperative WBRT. An additional 101 patients elected to be treated with mastectomy without postoperative radiation therapy. With a median follow-up of 7 years, there were no significant differences in local, regional, or distant recurrence, nor in breast-cancer-specific survival or overall survival.

Conclusions: We strongly support extreme oncoplasty plus WBRT as the default procedure of choice for patients with large multifocal/multicentric lesions amenable to reconstruction with volume displacement mammaplasty.