Immediate DIEP flap breast reconstruction following neoadjuvant therapy: Histopathological assessment of vascular integrity in internal mammary and deep inferior epigastric arteries.

BACKGROUND: The impact of neoadjuvant chemotherapy (CT) and radiotherapy (RT) on the microvasculature critical for autologous breast reconstruction remains unclear. The internal mammary artery (IMA) and deep inferior epigastric artery (DIEA) are key conduits in deep inferior epigastric perforator (DIEP) free flap surgery. Prior studies suggest that radiation and chemotherapeutic agents may induce vascular injury; however, the clinical relevance of such alterations in flap viability is debated. We aimed to evaluate whether neoadjuvant CT or combined CT+RT induce histopathological changes in the IMA and DIEA that could affect microvascular anastomosis or DIEP flap outcomes. METHODS: This single-center retrospective cohort study included 83 female patients with breast cancer who underwent nipple-sparing mastectomy followed by immediate DIEP flap reconstruction between 2019 and 2023. Patients were divided into three groups: no neoadjuvant therapy (Group 1), CT only (Group 2), and CT+RT (Group 3). Arterial segments from IMA and DIEA were histologically examined for tunica media thickness, lumen area, atherosclerosis, calcification, and elastic fiber fragmentation. Clinical parameters including anastomosis time and flap loss were also analyzed. Statistical analyzes were performed using ANOVA, Kruskal-Wallis, chi-square, or Fishers's exact tests, as appropriate. RESULTS: No significant differences were observed among the groups in terms of tunica media thickness (IMA, p = 0.230; DIEA, p = 0.327), lumen area (IMA, p = 0.061; DIEA, p = 0.134), atherosclerosis scores, or calcification. Elastic fiber fragmentation in the IMA also did not differ significantly (p = 0.627). Flap loss occurred in 5 of 83 patients (6%) and was comparable across the groups (p = 0.131). Mean anastomosis times were 60.7 ± 13.3, 55.1 ± 11.7, and 66.1 ± 14.8 in groups 1, 2, and 3, respectively (p = 0.011). CONCLUSION: Neoadjuvant CT and RT do not appear to cause significant histopathological deterioration of the IMA or DIEA. Immediate DIEP flap reconstruction performed at the time of mastectomy after neoadjuvant therapy appears to be microsurgically feasible and clinically safe.