Sigmoid Colon Metastasis from Endometrioid Carcinoma after a Long Disease-Free Interval Following Radiotherapy for Vaginal Recurrence: A Case Report and Review of the Literature.

A 76-year-old woman presented to a primary physician with a chief complaint of bloody stool. Nine years ago, she had undergone a total hysterectomy with bilateral salpingo-oophorectomy and pelvic lymphadenectomy for endometrioid carcinoma in the Department of Gynecology at our hospital. Her disease had been diagnosed as pT3aN0M0, Stage IIIA, with positive peritoneal cytology. Six years ago, she developed a vaginal recurrence and received 6 cycles of paclitaxel plus carboplatin chemotherapy, followed by external beam radiotherapy (54 Gy in 27 fractions) for the recurrent tumor, achieving a radiological complete response. A left ureteral stent had been placed for hydronephrosis associated with the vaginal recurrence, and she subsequently remained disease-free for 5 years. Her abdomen was soft and flat without tenderness, and a lower midline surgical scar was observed. Laboratory tests were almost within normal limits. Tumor markers were not elevated, with CEA 0.9 ng/mL and CA19-9 7 U/mL. CA125 measured 1 month ago during gynecologic follow-up was within the normal range (13 U/mL). Colonoscopy revealed a circumferential tumor at the sigmoid–descending colon junction ( Fig. 1 ). Gastrografin enema demonstrated an apple-core sign, and the endoscope could not be advanced beyond the stenotic segment. Biopsy specimens were obtained from the lesion. Contrast-enhanced CT showed wall thickening at the same location ( Fig. 2 ), without evidence of lymph node involvement or distant metastasis. Based on these findings, the patient was clinically diagnosed with primary sigmoid colon cancer and was referred to our department for surgery before the biopsy results were available. She was admitted the following day and underwent laparoscope-assisted sigmoidectomy 4 days later. Laparoscopic inspection of the abdominal cavity revealed a tumor at the sigmoid–descending colon junction. Although the lesion was adherent to the small intestine, no definitive invasion was identified. Peritoneal dissemination and endometriotic lesions were absent. No radiotherapy-related adhesions or fibrosis were observed within the radiotherapy field for the local recurrence. After adhesiolysis of the small intestine, laparoscopic sigmoidectomy with a systematic D3 lymph node dissection was completed as planned in accordance with the standard surgical strategy for primary sigmoid colon cancer. The histopathological findings of the preoperative biopsy, which had not been available at the time of surgery, became known after surgery. Biopsy revealed a tubular adenocarcinoma with relatively uniform, well-formed glands and no apparent irregular glandular architecture as seen in conventional colorectal adenocarcinoma. Immunohistochemical profiling was consistent with endometrioid carcinoma involving the colon. In the resected specimen, tumor cells morphologically similar to those identified in the biopsy were present. Their cytologic and architectural features closely resembled those of the uterine endometrioid carcinoma that had been resected 9 years ago ( Fig. 3 ). The colonic tumor showed no serosal involvement ( Fig. 3A , shaded area). Elastic Van Gieson staining demonstrated vascular invasion ( Fig. 3B ). Immunohistochemically, the tumor was positive for ER, PAX8, CK7, and vimentin, and negative for CDX2 and CK20 ( Fig. 4 ). No pathological lymph node metastasis was identified in the resected regional lymph nodes. Based on these histological and immunophenotypic findings, the lesion was diagnosed as metastatic endometrioid carcinoma to the sigmoid colon. The patient had an uneventful postoperative course and was discharged on POD 8. She subsequently received 6 cycles of paclitaxel plus carboplatin as adjuvant chemotherapy in the Department of Gynecology at our institution. She remains disease-free 25 months after sigmoidectomy. CDX2, caudal-type homeobox 2; CK7, cytokeratin 7; CK20, cytokeratin 20; ER, estrogen receptor; PAX8, paired box gene 8

Endometrioid carcinoma has an approximately 8% 5-year recurrence rate, with local recurrence, including vaginal recurrence, being the most common pattern of failure. 1 ) Distant metastases commonly involve the lungs, peritoneum, liver, and bones, 2 ) whereas colorectal metastasis is exceedingly rare and has been described only in isolated case reports. We report a case of metastasis to the sigmoid colon that developed after a 5-year disease-free interval following radiotherapy for vaginal recurrence of endometrioid carcinoma.

We performed surgery for a sigmoid colon metastatic recurrence that developed 9 years after surgery for endometrioid carcinoma and 5 years after treatment for vaginal recurrence. Although direct invasion of the colon or recurrence due to peritoneal dissemination from endometrial cancer is occasionally observed, colorectal metastasis as a distant hematogenous or lymphatic spread is rare. To our knowledge, a PubMed search of all available years up to September 2025 using the terms “endometrial cancer,” “colonic metastasis,” and “colorectal metastasis,” together with screening of related articles, identified 14 cases in total. 3 – 16 ) No language restrictions were applied. These reported cases and our case are summarized in Table 1 . The histological subtype was endometrioid carcinoma in 13 cases and serous carcinoma in 2 cases. Only about half of the reported cases were correctly diagnosed as colorectal metastasis before surgery, which suggests the diagnostic difficulty. The median interval from primary tumor surgery to colorectal metastasis was 6.5 years. This finding indicates that such metastases may occur as late recurrences. Muratori et al. summarized recurrences occurring more than 10 years after primary surgery for endometrial cancer and reported recurrence sites in the lung (3 cases), local or pelvic sites (3 cases), surgical scar (1 case), and colorectum (2 cases). 17 ) Although based on a limited number of cases, these findings suggest that atypical patterns of recurrence, such as colorectal metastasis, may occur in late recurrences. Including our case, there were 2 recurrent cases before the colorectal metastasis, and both were vaginal recurrences. None of the reported cases experienced recurrence after surgical resection of the colorectal metastasis during the reported follow-up period. These findings suggest that surgical resection of a colorectal metastasis may contribute to disease control. N/A, not available Immunohistochemistry is useful for differentiating primary colorectal cancer from colorectal metastasis of endometrioid carcinoma. Colorectal cancer typically shows CDX2 and CK20 positivity, whereas endometrioid carcinoma expresses ER, vimentin, CK7, and PAX8. 18 ) The immunoprofile of the tumor was consistent with the latter and lacked CDX2 and CK20. In combination with the histopathological findings, this supported a diagnosis of colorectal metastasis from endometrioid carcinoma rather than primary colorectal cancer. In the present case, the tumor showed no serosal exposure and demonstrated a growth pattern extending from the muscularis propria toward the mucosal surface. This morphology suggested that direct invasion from intra-abdominal local recurrence or disseminated lesions was unlikely. Because tumor cells were observed within vascular spaces and no pathological lymph node metastasis was identified, these findings suggested a possible hematogenous metastatic recurrence. Intraoperative peritoneal cytology should also have been performed at the time of sigmoidectomy to help assess the route of recurrence. Other reports have described endometrioid carcinoma arising in the colon in association with ectopic endometriosis. 19 , 20 ) However, in the present case, the patient had no history of endometriosis, and no evidence of endometriotic lesions was identified in the abdominal cavity and resected specimen, making this mechanism improbable. Chronic radiation-induced injury to the intestine may cause a variety of complications, including fibrosis, stricture, fistula formation, and adhesion. 21 ) In this case, radiotherapy had been performed as localized treatment for vaginal recurrence, so its effect on the operative field was expected to be limited. We began with laparoscopic inspection through the umbilical port and planned conversion to open surgery if severe adhesions were encountered. However, no apparent radiation-induced changes were observed, and laparoscopic surgery was completed safely. Radiotherapy for vaginal recurrence has been reported to achieve a 5-year pelvic control rate of 82%–92% and a 5-year overall survival rate of 50%–83% 22 – 26 ) and is therefore regarded as one of the standard treatment options. However, it has also been reported that approximately one-fourth of patients develop distant progression after salvage radiotherapy (5-year metastasis-free interval of 75.5%), 23 ) indicating the need for appropriate post-treatment management. Because distant metastases are associated with poor prognosis in endometrial cancer, 26 ) controlling metastatic lesions that occur after radiotherapy is a critical issue. Complete resection is an important prognostic factor for distant metastatic recurrence; therefore, surgery should be considered when metastases are resectable. 27 , 28 ) Although colorectal metastasis is rare, surgical treatment can still offer effective disease control when complete resection is achievable, as in the present case. In this case, no definitive pathological diagnosis could be made before surgery. Based on the endoscopic appearance, the lesion was regarded as a primary sigmoid colon cancer, and surgery was performed. A preoperative diagnosis of colorectal metastasis from endometrioid carcinoma would have been ideal. However, definitive diagnosis would have required additional immunohistochemical evaluation, and early surgical intervention was considered appropriate because the lesion exhibited stenosis. If metastatic endometrioid carcinoma had been diagnosed preoperatively, we would have performed PET-CT to search for other metastatic lesions and discussed the treatment strategy with the Department of Gynecology. We would also have adopted a more careful surgical approach, including peritoneal cytology, before proceeding to sigmoidectomy. Even after a prolonged disease-free interval, late recurrence of endometrial cancer should be kept in mind. Although such recurrence patterns are rare in long-term survivors after treatment for endometrial cancer, we should consider this possibility when determining the treatment strategy.

We encountered an extremely rare case of colorectal metastasis occurring 9 years after primary surgery and 5 years after radiotherapy for vaginal recurrence of endometrioid carcinoma. This case suggests that colonic metastatic recurrence, although rare, should be considered in long-term survivors of endometrial cancer. These findings illustrate the importance of recognizing atypical late recurrence when planning surgery in long-term survivors of endometrial cancer and suggest that complete surgical resection may provide effective disease control when colorectal metastasis is amenable to resection.

caudal-type homeobox 2 cytokeratin 7 cytokeratin 20 estrogen receptor paired box gene 8