Changes in Skin Vascularity in a Murine Model for Postmastectomy Radiation.

Background Postmastectomy radiation causes persistent injury to the breast microvasculature, and the prevailing assumption is that longer delays before breast reconstruction allow for recovery of blood supply. This study uses a murine model to examine the effects of radiation on skin vascularity to help determine when radiation-induced effects on the microvasculature begin to stabilize. Study Design Isogenic Lewis rats were divided into 2 groups: radiation therapy (XRT) (n = 24) and control (n = 24). The XRT rats received a breast cancer therapy human dose-equivalent of radiation to the groin, whereas control rats received no radiation. Animals were sacrificed at 4, 8, 12, and 16 weeks after completion of radiation. The vasculature was injected with Microfil, and groin skin was harvested for radiomorphometric analysis by microcomputed tomography. One-way analysis of variance with post hoc Tukey tests was used to determine significance between groups. Results Augmentation in vascularity was observed in the XRT group at 4 weeks after radiation compared to the control group (P = 0.045). Vessel number was decreased at 12 weeks (P = 0.002) and at 16 weeks (P = 0.001) in the XRT rats compared to control rats. Vessel separation in the XRT group was higher than that in the control group at 12 weeks (P = 0.009) and 16 weeks (P = 0.001). There was no change in vessel number and separation between weeks 12 and 16. Conclusions A period of augmented skin vascularity is seen after radiation injury followed by decreased vascularity which demonstrates stabilization at approximately 12 weeks in this murine model. This model can be used to further study breast flap vascularity and the optimization of the timing of delayed breast reconstruction.