Radiation-induced injury on surgical margins:a clue to anastomotic leakage after rectal-cancer resection with neoadjuvant chemoradiotherapy?

Background:Few studies on anastomotic condition after rectal-cancer resection and its effect on anastomotic leakage(AL)are available up to now.This study aimed to investigate potential radiation-induced injury left on surgical margins of anterior resection after neoadjuvant chemoradiotherapy(nCRT)and its association with AL.Methods:We retrospectively identified 161 consecutive patients who underwent anterior resection with nCRT,neoadjuvant chemotherapy without radiation(nCT)or no neoadjuvant therapy between 2014 and 2015.Tissue samples of resection margins were assessed using a specific histopathological score and microvessel density in submucosa.Propensity score matching was used to balance the baseline characteristics.Association between AL and histopathological features was analysed.Results:AL occurred in 13 of 54 patients undergoing nCRT,5 of 48 patients undergoing nCT and 7 of 59 patients without neoadjuvant therapy.Comparisons after matching showed median(range)histopathological scores as follows:3(0–8)vs 0(0–3)vs 0(0–2)for the proximal margin(P<0.001);4(2–9)vs 0(0–4)vs 0(0–3)for the distal margin(P<0.001).Correspondingly,mean(SD)microvessel densities were as follows:21.7(7.9)vs 27.2(8.6)vs 27.3(9.4)for the proximal margin(P=0.003);18.1(9.3)vs 25.2(12.9)vs 24.9(7.4)for the distal margin(P<0.001).Among patients undergoing nCRT,AL was associated with increased histopathological score(P=0.003)and decreased microvessel density(P=0.004)on the proximal margin.Conclusions:Surgical margins of rectal-cancer resection are exposed to certain radiation-induced injury after nCRT.AL is associated with aggravated radiation damage on the proximal margin.