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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. [ABSTRACT FROM AUTHOR]

Background: Chronic radiation proctitis (CRP), a common complication after radiotherapy for pelvic malignancies, compromises patient quality of life. Vascular damage and aberrant angiogenesis in the mucosal layer are essential histological features, but changes to the submucosal layer are unclear. Thus, we evaluated the histological characteristics and distribution changes of key angiogenic factors in full-layered human CRP samples.Methods: Thirty paraffin-embedded CRP and twenty-nine non-CRP tissues were used to evaluate histopathological changes. Immunohistochemistry with anti-CD34 antibody was performed to calculate microvascular density (MVD). Frozen tissues from eight CRP patients and five non-CRP controls were collected and analyzed by antibody array, which contained sixty human angiogenesis-related factors. Quality controls with positive and negative controls were performed during antibody array analysis. Two differentially expressed factors were confirmed by ELISA.Results: CRP lesions showed vasculopathy, fibrosis, mucosal ulceration, edema, and inflammatory cell infiltration. Human angiogenesis antibody array and ELISA confirmed the increased angiostatin in CRP lesions. Immunohistochemical staining showed dispersed distribution of angiostatin throughout the mucosal and submucosal layers in CRP lesions, while angiostatin accumulated within the vessel lumens in non-CRP tissues. MVD significantly decreased in the submucosal layer of CRP, suggesting a potential association with increased angiostatin.Conclusions: Angiostatin increased and had a distinct distribution in CRP lesions. Compensatory telangiectasia in the mucosa, vessel stenosis, and reduced MVD might attenuate blood flow in the submucosa and contribute to CRP progression. Restoration of vascular functionality by promoting angiogenesis in the submucosal layer may help alleviate CRP in clinical practice. [ABSTRACT FROM AUTHOR]