What is the role of endoscopy (procedure that visually examines the upper part of the gastrointestinal tract) in diagnosing and staging ovarian carcinoma in a postmenopausal woman with abdominal symptoms?

Endoscopy in Ovarian Carcinoma: When and Why It's Indicated

Endoscopy (colonoscopy/gastroscopy) is needed in ovarian carcinoma when tumor markers suggest a gastrointestinal primary rather than ovarian origin—specifically when the CA-125/CEA ratio is ≤25 or when CEA and CA 19-9 are elevated. 1, 2

Primary Diagnostic Pathway

The initial evaluation of suspected ovarian cancer does not routinely include endoscopy. The standard approach prioritizes:

• Transvaginal ultrasonography with color Doppler as the first-line imaging modality 1
• Serum tumor markers including CA-125, CEA, and CA 19-9 measured simultaneously 1, 2
• Contrast-enhanced CT of abdomen and pelvis (with oral contrast) as the imaging modality of choice for staging 3

Specific Indications for Endoscopy

When Gastrointestinal Origin is Suspected

Endoscopy becomes necessary when distinguishing between primary ovarian cancer and gastrointestinal metastases to the ovary. This clinical scenario arises because:

• Mucinous ovarian tumors can be difficult to differentiate from gastrointestinal primaries that have metastasized to the ovaries 2
• The CA-125/CEA ratio provides critical guidance: a ratio >25 favors ovarian origin, while a ratio ≤25 suggests gastrointestinal origin and warrants colonoscopy/gastroscopy 1, 2, 4
• Elevated CEA or CA 19-9 in addition to CA-125 should prompt consideration of endoscopy to exclude colorectal or pancreatic primary tumors 1, 2

Clinical Algorithm

The European Society of Gynecologic Oncology recommends this approach 1:

1. Perform transvaginal ultrasound and measure CA-125, CEA, and CA 19-9
2. Calculate the CA-125/CEA ratio
3. If ratio ≤25: Proceed with colonoscopy and/or gastroscopy before surgical exploration
4. If ratio >25 and ultrasound shows malignant features: Proceed directly to surgical exploration for definitive diagnosis and staging

Why This Matters for Patient Outcomes

Distinguishing primary ovarian cancer from gastrointestinal metastases fundamentally changes surgical approach and prognosis. 3, 5

• Primary ovarian cancer requires aggressive cytoreductive surgery by a gynecologic oncologist, including total hysterectomy, bilateral salpingo-oophorectomy, omentectomy, and lymph node assessment 3
• Gastrointestinal primaries with ovarian metastases require different surgical strategies focused on the primary tumor site and may involve colorectal surgeons 1
• Optimal cytoreduction (residual disease <1.5 cm) significantly improves survival in true ovarian cancer, making accurate preoperative diagnosis critical 5, 6

Common Pitfalls to Avoid

Do not perform endoscopy routinely in all ovarian cancer cases—this is unnecessary and delays appropriate treatment. 3 The ACR Appropriateness Criteria explicitly state that contrast enema is not routinely used for preoperative staging of ovarian cancer, with the exception being when there is concern about colonic versus ovarian primary based on imaging findings and tumor marker ratios. 3

Do not rely on CA-125 alone to make surgical decisions, as it has only 50% sensitivity for stage I disease and can be elevated in benign conditions like endometriosis, pelvic inflammatory disease, and cirrhosis. 3, 2

Imaging Takes Priority Over Endoscopy

For confirmed ovarian cancer staging and follow-up, imaging modalities supersede endoscopy:

• CT with IV and oral contrast remains the gold standard for initial staging and detecting recurrence 3
• FDG-PET/CT is considered equivalent to CT and provides management-changing information about resectability 3
• Second-look laparotomy is no longer routinely performed because noninvasive imaging adequately diagnoses gastrointestinal recurrence 3

The role of endoscopy in ovarian carcinoma is therefore highly selective and limited to cases where the differential diagnosis includes gastrointestinal primary malignancy based on specific tumor marker patterns. 1, 2