https://www.selleckchem.com/products/avelumab.html Transanal minimally invasive surgery (TAMIS) is mainly used for benign tumors of the rectum, but there are few reports on treating malignant tumors of the rectum with a large volume. The aim of this study was to evaluate the feasibility and safety of TAMIS for resection of rectal malignant tumors. A 57-year-old patient was pathologically diagnosed as rectal malignancy before surgery. Computed tomography (CT), magnetic resonance imaging (MRI), fludeoxyglucose-18F (18F-FDG), and endoscopic mucosal biopsy were performed to assess the tumor location and preoperative size. There were no contraindications in all preoperative examinations. We applied TAMIS technology to perform the operation on this patient, And the operative time, the amount of blood loss, the length of hospital stay, the cost of hospital stay, surgical complications, postoperative complications and other relevant data were all collected. The operation was successful, the operation time was 45 min, 10 mL of intraoperative blood loss, and the length of stay was 3 days, a tumor of a maximum diameter of 4 cm being completely removed. There were no related complications or recurrence during postoperative follow-up. The pathological results were tubular villous adenoma with low-grade intraepithelial neoplasia, and a focal area of high-grade intraepithelial neoplasia. The pathological stage was T1N0M0. At 3-month follow-up there were no signs of recurrence. The patient was followed up for 5 years after the operation and there was no tumor recurrence or metastasis in other parts and no other discomfort. TAMIS is less commonly used in rectal malignancies, especially for tumors with larger diameters. We successfully performed complete resection of a 4-cm rectal malignant tumor with TAMIS. Given its low risk, low cost, simple operation, and few complications, TAMIS can be used for more indications of rectum diseases.Hyperprogressive disease (HPD) is a phenomenon de