A 52-year-old man with cirrhosis presents with a hepatic nodule detected on ultrasound. Serum alpha-fetoprotein (AFP) is markedly elevated at 1200 ng/mL. Which malignancy is most commonly associated with elevated AFP levels in this clinical context?

Explanation

## Tumor Marker: Alpha-Fetoprotein (AFP) ### Clinical Context AFP is a glycoprotein normally produced by fetal liver and yolk sac. Elevated levels in adults are pathologic and associated with specific malignancies. ### Most Common Association: Hepatocellular Carcinoma (HCC) **Key Point:** AFP >400 ng/mL in a cirrhotic patient with a nodule >1 cm is diagnostic of HCC without need for biopsy (AASLD criteria). **High-Yield:** - **Sensitivity:** ~60–70% for HCC (varies by stage) - **Specificity:** ~95% when >400 ng/mL - **Cutoff for HCC diagnosis:** >20 ng/mL (elevated); >400 ng/mL (highly specific) ### AFP in Other Malignancies | Malignancy | AFP Elevation | Frequency | Clinical Note | |---|---|---|---| | **Hepatocellular carcinoma** | Very common | 60–70% | Most common source of elevated AFP | | Gastric cancer | Rare | <5% | Only in advanced/diffuse type | | Pancreatic cancer | Rare | <2% | Not a useful marker | | Cholangiocarcinoma | Rare | <5% | Mild elevation if any | | Germ cell tumors | Common | 50–80% | Yolk sac component | **Clinical Pearl:** AFP is also elevated in benign conditions (cirrhosis, chronic hepatitis B/C, pregnancy) but the combination of cirrhosis + nodule + very high AFP (>400 ng/mL) is virtually diagnostic of HCC. ### Why HCC is the Answer In a cirrhotic patient with imaging findings and markedly elevated AFP, hepatocellular carcinoma is the overwhelming most common malignancy. HCC is the most frequent cancer complication of cirrhosis and AFP is its hallmark tumor marker.