A 48-year-old woman with a history of ovarian cancer (stage IIIC, serous adenocarcinoma) completed 6 cycles of platinum-based chemotherapy 8 months ago. She now presents with rising serum CA-125 levels (from 12 U/mL to 85 U/mL over 2 months) and mild abdominal discomfort. Clinical examination is unremarkable. What is the most appropriate next investigation to assess for recurrence?

Explanation

## Investigation for Suspected Ovarian Cancer Recurrence ### Clinical Context: Biochemical Recurrence **Key Point:** Rising CA-125 in a patient with prior ovarian cancer is highly suggestive of recurrence. The next investigation should localize the site(s) of recurrent disease and guide treatment decisions (surgery vs. chemotherapy). **High-Yield:** In ovarian cancer surveillance: - **Biochemical recurrence** (rising CA-125 alone) precedes clinical/radiological recurrence by weeks to months - Imaging should be performed when CA-125 rises to guide intervention - CECT is the first-line imaging modality for detecting recurrent disease ### Why CECT Abdomen and Pelvis? | Investigation | Sensitivity for Recurrence | Clinical Role | Limitation | |---|---|---|---| | **CECT abdomen/pelvis** | 60–80% | First-line imaging; detects nodal, peritoneal, visceral recurrence | May miss small peritoneal deposits (<5 mm) | | Diagnostic laparoscopy | ~95% | Gold standard for peritoneal disease; therapeutic (debulking) | Invasive; not first-line; reserved for selected cases | | TVS with Doppler | 40–50% | Limited to pelvic masses; poor for peritoneal/distant spread | Insensitive for recurrence detection | | PET-CT | 70–85% | High sensitivity; useful for equivocal CT findings | Expensive; not first-line; reserved for staging before secondary debulking | **Clinical Pearl:** CECT is preferred because: 1. It detects the majority of recurrent disease (peritoneal, nodal, visceral) 2. It guides treatment decisions (resectable vs. unresectable recurrence) 3. It is non-invasive and reproducible for follow-up 4. It is cost-effective and widely available ### Management Pathway Based on CECT Findings ```mermaid flowchart TD A[Rising CA-125 in ovarian cancer survivor]:::outcome --> B[CECT abdomen and pelvis]:::action B --> C{Findings?}:::decision C -->|Localized, resectable disease| D[Secondary cytoreductive surgery]:::action C -->|Extensive peritoneal/distant spread| E[Platinum-based chemotherapy]:::action C -->|No findings on CT| F[Consider laparoscopy or PET-CT]:::decision D --> G[Optimal debulking improves survival]:::outcome E --> H[Assess response with CA-125 and imaging]:::outcome ``` **High-Yield:** Secondary cytoreductive surgery is considered in patients with isolated recurrence and good performance status. CECT helps identify candidates by determining resectability.