Single case report documents ruptured ovarian metastases after colon cancer surgery

A 54-year-old woman developed bilateral ovarian metastases from colon cancer 19 months after apparently curative surgery, and one tumor ruptured with active bleeding as surgeons entered her abdomen. The case, reported by Zheng and colleagues, combined a stage pT4aN0M0 ascending colon adenocarcinoma, eight cycles of adjuvant XELOX chemotherapy, extensive peritoneal seeding, and pathology showing metastatic colorectal adenocarcinoma without signet-ring cells. Although the absence of signet-ring cells meant that the tumors did not meet the strict definition of a Krukenberg tumor, their bilateral growth, large size, and rupture demonstrated that this non-signet-ring form can also behave aggressively. As a single-patient case report, the findings cannot establish the effectiveness of the treatment strategy, but they provide a detailed account of a rare and potentially fatal pattern of colorectal cancer recurrence.

The patient initially underwent laparoscopic right hemicolectomy in July 2024. Pathology classified the 2.5 by 2.5 by 0.7-centimeter tumor as moderately to well-differentiated adenocarcinoma that had invaded the visceral peritoneum, designated pT4a. All 23 examined lymph nodes were negative, and there was no omental metastasis, giving the original tumor a stage IIB, or pT4aN0M0, classification. Perineural invasion was also identified. She completed eight cycles of XELOX, comprising oxaliplatin and oral capecitabine, between August 2024 and March 2025, after which surveillance was scheduled every three months with clinical examinations, tumor markers, ultrasound, and contrast-enhanced CT every six months. She attended two follow-up visits without symptoms or detected abnormalities but did not return for later appointments for personal reasons.

Progressive lower-abdominal distension and mild discomfort finally prompted evaluation in February 2026. The remaining serum marker results were markedly abnormal: CEA reached 188.25 nanograms per milliliter, compared with a reference value below 5; CA19-9 reached 462.77 units per milliliter, versus below 35; and CA125 reached 303.91 units per milliliter, also versus below 35. Ultrasonography showed bilateral adnexal masses. CT then identified multiple cystic-solid pelvic masses, the largest measuring 94 by 73 millimeters, together with diffuse peritoneal thickening and apparent involvement of the bladder and rectal walls. Colonoscopy found no recurrence at the colonic anastomosis. Whole-body fluorine-18 fluorodeoxyglucose PET-CT showed heterogeneous uptake in the pelvic masses and diffuse peritoneal abnormality with ascites, leading clinicians to consider metastatic colorectal cancer involving the ovaries, although a primary ovarian malignancy could not be excluded radiologically.

A multidisciplinary team including radiologists, gastrointestinal and gynecologic surgeons, anesthesiologists, and medical oncologists judged the pelvic disease potentially resectable even though complete cytoreduction was not expected because of the visible peritoneal involvement. They selected surgery rather than a purely palliative approach, reasoning that delay could allow further growth, hemorrhage, or bowel obstruction and could narrow the opportunity for macroscopic tumor removal. When the abdominal cavity was opened in March 2026, however, the team encountered massive hemorrhagic ascites and a tense cystic-solid mass about 14 centimeters across with active bleeding from ruptured surfaces. The authors could not determine the precise time of rupture and proposed that it may have occurred at some point before surgery. The procedure included bilateral salpingo-oophorectomy, omentectomy, placement of a hyperthermic intraperitoneal chemotherapy catheter, and exploration of the abdominal cavity.

Surgery also revealed numerous miliary peritoneal implants, and complete cytoreduction was not achieved; the residual disease was classified as CC-2/3. The previous colonic anastomosis was intact, without obstruction or local recurrence. Microscopic examination confirmed bilateral ovarian metastatic adenocarcinoma of colorectal origin. Immunohistochemistry was CK7-negative, CK20-positive, and CDX2-positive, while SATB2 was partially positive and PAX-8 negative. No signet-ring cells were found, excluding a true Krukenberg tumor, and the metastatic lesions retained a mismatch-repair-proficient, microsatellite-stable profile. The Ki-67 index rose from 50% in the primary tumor to 70% in the ovarian metastases, and p53 showed mutant-type expression. Genetic testing of the metastases identified eight somatic variants, including NRAS p.G12D and TP53 p.C176R, with no germline variants detected. The tumor mutation burden was 8.33 mutations per megabase, classified as high.

After surgery, the patient received three sessions of hyperthermic intraperitoneal chemotherapy on postoperative days one, three, and five. Each 4,000-milliliter perfusion contained sterile water, 4 milligrams of raltitrexed, and 200 milligrams of oxaliplatin and was delivered at a target intraperitoneal temperature of 42 to 43 degrees Celsius for 60 minutes. The regimen was individualized according to the institution’s experience and the patient’s tolerance, rather than tested in a controlled comparison. Catheters were removed on postoperative day seven after drainage became clear and the daily volume fell below 100 milliliters. During 90 days of postoperative surveillance, the patient experienced no major complication: there was no anastomotic leak, intra-abdominal infection, recurrent hemorrhage, bowel obstruction, or catheter-related event requiring intervention. Her Clavien-Dindo complication grade was 0 to 1.

Following multidisciplinary review of the molecular findings, the patient began XELOX chemotherapy every three weeks together with bevacizumab and serplulimab, an antibody targeting PD-1. The researchers cited the phase 2 portion of the randomized ASTRUM-015 trial as supporting this combination. In that first-line trial of metastatic colorectal cancer, adding serplulimab and a bevacizumab biosimilar to XELOX was associated with longer median progression-free survival than placebo plus bevacizumab and XELOX: 17.2 versus 10.7 months, with a hazard ratio of 0.60. The report also noted benefits in microsatellite-stable and KRAS-mutant subgroups, but the NRAS subgroup was very small. After six cycles of triplet treatment, imaging and tumor-marker assessments showed stable disease. The anti-PD-1 drug was subsequently withheld because of an immune-related adverse event, and the patient remained under regular follow-up at the time of publication.

Ovarian metastasis is uncommon among women with colorectal cancer, with reported frequencies of approximately 0.8% to 7.4%, and is generally associated with unfavorable outcomes. A strict Krukenberg tumor contains signet-ring cells in more than 10% of the lesion, whereas non-signet-ring metastases may retain glandular features resembling the primary adenocarcinoma. Because Krukenberg tumors are often regarded as particularly aggressive and chemoresistant, other histologic forms can sometimes appear less threatening. This case challenges that simple distinction. The patient had no signet-ring cells, yet her tumors involved both ovaries, reached at least 14 centimeters, accompanied extensive peritoneal dissemination, ruptured with active hemorrhage, and recurred after a standardized adjuvant regimen. The report therefore emphasizes that the absence of signet-ring cells does not guarantee indolent behavior. It does not, however, establish that all non-signet-ring ovarian metastases are equally aggressive, a conclusion that would require data from larger series.

The timing was also consistent with patterns described in the report’s small literature review. Among cases of metachronous ovarian metastasis following curative resection of colorectal cancer without initial distant metastasis, the interval ranged from about 12 months to three years, with most occurring within two years. Many previous reports involved unilateral, relatively localized disease without peritoneal implants, whereas this patient had bilateral tumors and widespread seeding. Her spontaneous rupture was not identified in the other summarized cases. The pT4a classification may be important because invasion of the visceral peritoneum can expose tumor cells directly to the peritoneal cavity, potentially enabling transcoelomic spread to the ovaries and peritoneal surfaces without requiring lymph-node involvement. This provides a plausible route in a patient whose sampled nodes were negative. It remains a proposed mechanism, however, rather than a route directly demonstrated in this individual patient.

The case is also limited by several important constraints. It describes one patient, so the observed course and disease stabilization cannot be extrapolated to other people with colorectal ovarian metastases or establish a treatment benefit. The contribution of hyperthermic intraperitoneal chemotherapy is especially uncertain: the report notes that the phase 3 PRODIGE 7 trial did not demonstrate a significant overall-survival benefit from adding HIPEC to complete cytoreductive surgery in the setting studied, and complete cytoreduction was not achieved here. Follow-up was also relatively short, long-term survival was unknown, and systemic treatment was modified after an immune-related adverse event. The selection of surgery, HIPEC, bevacizumab, and serplulimab was therefore individualized and partly based on emerging evidence. What the case reliably documents is a rare rupture of bilateral non-signet-ring ovarian metastases after treated pT4a colon cancer, followed by cytoreductive surgery and systemic therapy that produced stable disease at the reported follow-up. It highlights the need for further prospective evidence while showing how molecular testing and multidisciplinary review shaped care in one complex recurrence.

Subject of Research: Ruptured bilateral ovarian metastases following resection of stage pT4a colorectal cancer

Article Title: Metachronous bilateral ovarian metastasis with spontaneous rupture following curative resection of stage T4a colon cancer: a case report and literature review

Article References: Zheng, Y., & Zhang, Z. (2026). Metachronous bilateral ovarian metastasis with spontaneous rupture following curative resection of stage T4a colon cancer: a case report and literature review. Frontiers in Oncology, 16, Article 1950347. https://doi.org/10.3389/fonc.2026.1950347

Image Credits: AI Generated

DOI: 10.3389/fonc.2026.1950347

Keywords: colorectal cancer, ovarian metastasis, tumor rupture, peritoneal carcinomatosis, NRAS mutation, high tumor mutational burden, cytoreductive surgery, HIPEC, immune checkpoint therapy, case report, Metachronous, bilateral