A 62-year-old woman is diagnosed with endometrial cancer and undergoes staging investigations. Which is the most common site of metastasis in endometrial cancer?

Explanation

## Metastatic Spread in Endometrial Cancer **Key Point:** The most common site of metastasis in endometrial cancer is the **pelvic and para-aortic lymph nodes**, reflecting the lymphatic drainage pattern of the uterus. ### Lymphatic Drainage and Metastatic Pattern | Site of Metastasis | Frequency | Mechanism | Clinical Significance | | --- | --- | --- | --- | | **Pelvic & para-aortic lymph nodes** | 5–20% (Stage III) | Direct lymphatic drainage from uterus | Determines staging and treatment (radiation, chemotherapy) | | Lungs | 5–10% (distant metastasis) | Hematogenous spread | Late manifestation, usually with advanced disease | | Liver | 2–5% (distant metastasis) | Hematogenous spread | Less common than lung metastasis | | Brain | <1% (distant metastasis) | Hematogenous spread | Rare; usually terminal event | ### Pathways of Spread 1. **Lymphatic spread (most common):** - Uterine lymphatics drain to pelvic nodes (obturator, internal iliac, external iliac) - Further drainage to para-aortic (lumbar) nodes - This is the primary route of metastasis in endometrial cancer 2. **Hematogenous spread (less common):** - Via uterine veins → pelvic veins → IVC → lungs - Lungs are the most common distant organ involved 3. **Peritoneal spread:** - Direct extension through myometrium and serosa - Peritoneal cytology is part of staging **High-Yield:** Lymph node metastasis is the most important prognostic factor in endometrial cancer. Pelvic lymph node involvement alone = Stage IIIC1; para-aortic involvement = Stage IIIC2. This distinction drives adjuvant therapy decisions. ### Clinical Pearl **Clinical Pearl:** In early-stage endometrial cancer (Stage I–II), lymph node metastasis is present in 5–10% of cases. However, in high-risk histologies (serous, clear cell) or high-grade tumors, the risk of nodal involvement increases significantly (up to 20–30%), necessitating comprehensive staging with pelvic and para-aortic lymphadenectomy. **Warning:** Distant metastases (lungs, liver, brain) are uncommon at presentation and usually indicate advanced disease. Do not confuse lymph node metastasis (Stage III, regional) with distant metastasis (Stage IV).