A 42-year-old woman undergoes cervical biopsy for a CIN3 lesion identified on colposcopy. The pathologist reports a 2 cm lesion with invasion into the superficial stroma. What is the most appropriate next investigation to assess for metastatic disease?

Explanation

## Staging Investigation for Early Invasive Cervical Cancer **Key Point:** MRI pelvis with contrast is the gold standard imaging modality for local and regional staging of early invasive cervical cancer. It provides superior soft-tissue contrast for assessing parametrial involvement, vaginal extension, and pelvic lymph node status. ### Pathological Findings Indicating Invasive Disease The biopsy shows: - Invasion into superficial stroma (Stage IB1 or early IB2 cervical cancer) - Requires complete staging workup to guide treatment (surgery vs. chemoradiation) ### Role of MRI in Cervical Cancer Staging **High-Yield:** MRI pelvis is superior to CT for: - Assessing **parametrial invasion** (critical for treatment planning) - Evaluating **vaginal involvement** - Detecting **pelvic lymph node metastases** (though less sensitive than PET-CT for distant nodes) - Determining **tumor size and extent** within the cervix **Mnemonic: MRI for LOCAL staging** — Magnetic Resonance Imaging evaluates parametrial and local extension; CT/PET for distant metastases. ### Staging Workup Algorithm ```mermaid flowchart TD A[Histologically confirmed invasive cervical cancer]:::outcome --> B{Stage assessment needed}:::decision B --> C[MRI pelvis with contrast]:::action C --> D{Parametrial involvement?}:::decision D -->|Yes| E[Stage IB2-IIA2]:::outcome D -->|No| F[Stage IB1]:::outcome F --> G[Consider chest imaging + labs]:::action E --> H[Consider chest imaging + labs]:::action ``` ### Complementary Investigations After MRI: - **Chest X-ray:** To exclude pulmonary metastases (Stage IVB) - **CBC, renal function:** Baseline before chemoradiation - **PET-CT:** Reserved for advanced disease (Stage IB2 with high-risk features) or to assess distant metastases **Clinical Pearl:** In resource-limited settings (including India), MRI may not always be available; CT pelvis + chest X-ray is an acceptable alternative, though less sensitive for parametrial invasion.