Endometrial Cancer Metastatic to the Sigmoid Colon and Pelvic Retroperitoneal Space: A Case Report.

Background/aim: The majority of colorectal tumors are primary colorectal cancers (CRCs), which commonly develop distant metastases in advanced stages. In contrast, secondary involvement of the colon by tumors originating from other organs is rare. Endometrial cancer (EC) typically metastasizes to the vagina, lungs, and peritoneum, with colonic metastasis being exceedingly uncommon.

Case report: A 76-year-old female patient presented with abdominal pain. Her medical history was notable for multiple malignancies, including Stage I left breast cancer, Stage IA endometrial cancer, and Stage IIA right breast cancer. Laboratory tests showed elevated levels of cancer antigen (CA)125 (234.5 U/ml) and CA19-9 (110.0 U/ml) were elevated. Contrast-enhanced computed tomography revealed large pelvic cystic tumor and irregular wall thickening of the sigmoid colon. Intraoperative findings showed that the small intestine and sigmoid colon were adherent to the pelvic tumor, forming a large single mass. To achieve en bloc and R0 resection, pelvic tumor resection, high anterior resection, enterectomy, and temporary ileostomy were performed. The histopathological diagnosis confirmed metastasis of EC to the sigmoid colon and pelvic retroperitoneal space, with 2 of 12 lymph nodes positive for metastasis. All surgical margins were negative, and no recurrences were observed nine months post-discharge.

Conclusion: We present a rare case of EC metastasis to the colon and pelvic retroperitoneal space with lymph node metastases, successfully treated with en bloc surgical resection. Because EC and CRC exhibit morphological and pathological similarities, laboratory testing for tumor markers, including CA125, may be useful for the preoperative diagnosis of colonic tumors in patients with a history of EC.