Colorectal anastomotic leakage after conversion surgery for advanced endometrial cancer treated with lenvatinib plus pembrolizumab: a case report.

The combination therapy of lenvatinib plus pembrolizumab (LP) is increasingly recognized as an important second-line regimen for advanced or recurrent endometrial cancer (EC). However, the safety and efficacy of conversion surgery with low anterior rectal resection for unresectable EC following LP therapy is unknown. A 37-year-old woman was referred with unresectable EC with pleural fluid, peritoneal dissemination, and ascites. After the failure of first-line platinum-based chemotherapy, she was administered LP as second-line treatment. After 10 treatment cycles, uterine and peritoneal tumors significantly reduced in size, except the left ovarian metastatic tumor which became slightly larger. Cytoreductive surgery, including low anterior resection of the rectum and colorectal anastomosis, achieved complete resection. However, on postoperative day 11, the patient experienced an anastomotic leakage around the colorectal anastomosis site, necessitating a double-barreled colostomy and percutaneous drainage. She was discharged 15 days after the second surgery and resumed LP therapy after 44 days following the second surgery. We report a case in which conversion surgery after LP therapy was conducted for unresectable advanced endometrial cancer. Our findings indicate that if bowel resection is required, a longer preoperative withdrawal period may be necessary to prevent postoperative anastomotic leakage.