The Impact of Radiation and Its Timing on Donor Internal Mammary Vessel Histopathology at the Time of Autologous Microvascular Breast Reconstruction
We evaluate the impact of radiation and its early versus late effects on internal mammary vessel histomorphometry and implications for autologous breast reconstruction.Methods
Patients received no radiation or radiation within the previous 6 weeks (early) or at least 6 months prior to biopsy (late) of the internal mammary vessels during free flap surgery. Clinical outcomes, and vessel measurements and markers for macrophages, smooth muscle actin (SM-ACTIN), elastin, and collagen were analyzed.Results
We analyzed 36 internal mammary arteries (IMAs) and veins (IMV) in 22 patients. Six had no radiation, 12 had radiation less than 6 weeks, and 18 had radiation more than 6 months ago. Demographics, surgical variables, and cardiovascular comorbidity did not differ between groups. Macrophage counts were higher in patients who had radiation (p < 0.001) and in the early group when compared with the late group (p = 0.03). There were similar findings in the IMV. Intimal thickness of the IMA increased significantly after radiation (p < 0.001), particularly in the late group when compared with the early group (p = 0.007). Intima-media thickness of the IMV was significantly elevated (p = 0.02) after radiotherapy. Radiation decreased percentage of SM-ACTIN in the IMA (p = 0.05). Other histomorphometric parameters did not differ significantly.Conclusion
Higher macrophage counts but less intimal thickening of the IMA differentiates donor vessels utilized within 6 weeks of radiotherapy and those performed after 6 months or more. Although the timing of reconstruction is based on several other factors, histologic parameters support reconstruction within 6 weeks of radiation therapy.