Evaluation of Breast Volume following Lumpectomy Combined with Oncoplastic Reduction Mammaplasty and Radiation Therapy.

Abstract

Results of breast conserving therapy with adjuvant radiation therapy (RT) may be impacted by RT effects on breast symmetry, ptosis, and volume. This investigation sought to quantify these effects on breast volume in the setting of oncoplastic reduction mammaplasty performed at the time of lumpectomy. A single-center, retrospective review included women who underwent bilateral oncoplastic reduction mammaplasty simultaneous with lumpectomy (2017 to 2021). Breast volumes were calculated using mammograms 1, 2, and 3 years after RT. Paired t tests compared volumes of irradiated to nonirradiated breasts each year. Multivariable regression explored effects of other variables on volume changes. Thirty-two patients completed 2 years of mammograms, and 28 completed 3 years. At year 1, an irradiated breast comprised approximately 93% of the volume of its nonirradiated counterpart, decreasing approximately 5% (95% CI, 0.4% to 11%; P = 0.04), to 88% of volume at year 2. Comparing years 1 and 3, an irradiated breast comprised 84% of the volume of its nonirradiated counterpart, a 9% volume loss (95% CI, 2.5% to 15%; P = 0.008). Comparing baseline to year 3, multivariable regression demonstrated increasing age was protective against greater volume differences, with a 0.70% increase in volume retained per year of age (95% CI, 0.12% to 1.28%; P = 0.02). Findings demonstrate significant volume discrepancies between irradiated and contralateral nonirradiated breasts over a 3-year period following oncoplastic reduction/RT. Volume difference increased over time, highlighting the long-term impact of RT and need for continuing interventions to address asymmetry. These results may guide preoperative planning and patient counseling regarding long-term results.