West Asia Organization for Cancer Prevention (WAOCP), APOCP's West Asia Chapter. Asian Pacific Journal of Cancer Prevention 1513-7368 24 8 2023 08 01 Pretreatment Microvessel Density for Predicting of Tumor Responsiveness to Neoadjuvant Chemoradiotherapy of Locally Advanced Rectal Cancer 2697 2703 90755 10.31557/APJCP.2023.24.8.2697 EN Chinakrit Boonya-Ussadorn Department of Surgery, Phramongkutklao Hospital, Thailand. 0000000247595916 Thirayost Nimmanon Department of Pathology, Phramongkutklao College of Medicine, Thailand. 0000000187651268 Sahaphol Anannamcharoen Department of Surgery, Phramongkutklao Hospital, Thailand. 000000030274564X Journal Article 2023 03 24 Objective: This study aimed to assess whether pretreatment tumor tissue microvessel density (MVD) could be a potential predictive marker for Mandard response in LARC treated with nCRT. Methods: A retrospective analysis was performed in pretreatment paraffin-embedded specimens of 31 pathologically confirmed rectal adenocarcinoma. All patients received nCRT and subsequent total mesorectal resection. Tumor MVD was determined by an average number of counted CD34-stained endothelial cells from two selected fields at 200x magnification in each slide and categorized into two groups: low MVD (</=60) and high MVD (> 60). The tumor response was determined using the Mandard tumor regression grading system. The subjects were grouped according to their TRG into responder (TRG 1-3) and non-responder (TRG 4–5). Result: Twenty out of thirty-one patients (64.5%) were defined as responders. Eleven patients (35.5%) were defined as non-responders. MVD was significantly associated with tumor responsiveness to nCRT (p < 0.05). High MVD was shown to be an independent risk factor associated with tumor resistance to nCRT (OR, 22.58; 95% CI, 1.943-262.34; p = 0.013). A strong correlation was found between MVD and TRG (correlation coefficient value of 0.642, p <0.01), between MVD and vascular invasion (correlation coefficient value of 0.618, p <0.01), and between nodal involvement and vascular invasion (correlation coefficient value of 0.521, p <0.01). A moderate correlation was found between nodal involvement and vascular invasion (correlation coefficient value of 0.406, p <0.05). Conclusion: High MVD in pretreatment tumor tissue was significantly associated with the tumor resistance to nCRT. https://journal.waocp.org/article_90755_1d347663cbd39dbd18a117221dac8a59.pdf