Effects of timing in the applications of radiotherapy after transverse rectus abdominis musculocutaneous flap in rats

The present study aimed to investigate flap status in relation to the timing of radiotherapy (RT) in an experimental rat model of irradiated transverse rectus abdominis musculocutaneous (TRAM) flap.

Fifty-six adult male Sprague-Dawley experiments were separated in seven groups in terms of flap surgery and RT. The groups comprised sham group, control (Ctrl) group, RT group, and RT plus surgery (RT+Surg) group, which was further separated in four groups depending on the timing of postoperative RT as RT+Surg-10 (RT on postoperative 10th day), RT+Surg-20 (RT on postoperative 20th day), RT+Surg-30 (RT on postoperative 30th day), and RT+Surg-40 (RT on postoperative 40th day). All the rats were sacrificed 8 weeks after the RT administration for histopathological analysis.

Compared with the RT+Surg-10 and RT+Surg-20 groups, the hyalinization and collagenization scores in RT+Surg-30 were determined to be significantly lower. Fibrosis scores were lower in the RT+Surg-30 group compared with the RT+Surg-20 group, whereas significantly lower inflammation scores were determined in the RT + Surg-40 group and significantly higher dermal thickness in the RT+Surg-30 group compared with the RT+Surg-10 group.

The findings from this model of irradiated flap revealed the significance of the time lag among flap application and postoperative RT for histopathological outcome, emphasized the potential role of at least a 30- to 40-day interval between surgery and RT in achieving more favorable flap status.