Is Alpha-Fetoprotein (AFP) used as a tumor marker for seminoma?

Alpha-Fetoprotein (AFP) Should Not Be Used as a Tumor Marker for Pure Seminoma

Pure seminoma does not produce AFP, and any elevation of AFP in a patient with histologically diagnosed seminoma indicates the presence of nonseminomatous elements, requiring management as a nonseminomatous germ cell tumor.

Relationship Between AFP and Seminoma

AFP in Seminoma Diagnosis

• AFP is not produced by pure seminoma cells 1
• AFP is a serum tumor marker specifically produced by nonseminomatous cells, particularly embryonal carcinoma and yolk sac tumor components 1
• The approximate half-life of AFP is 5-7 days 1, 2

Diagnostic Implications

• When patients with histologically "pure" testicular seminoma have an elevated AFP level, it is generally assumed that an undetected focus of nonseminoma is present 1
• Patients with raised AFP should be managed as having nonseminoma, even if histology shows pure seminoma 1
• A significantly elevated serum AFP can establish the diagnosis of a mixed germ cell tumor in a patient whose histopathologic diagnosis is pure seminoma 1

Clinical Management Considerations

Pre-Orchiectomy Testing

• All patients suspected of having testicular germ cell tumors should have blood drawn for measurement of serum AFP and hCG before diagnostic orchiectomy 1
• Pre-orchiectomy marker testing helps establish the diagnosis and aids in interpreting post-orchiectomy tumor marker levels 1

Borderline AFP Elevations

• Borderline elevated AFP values should be interpreted cautiously 1
• Some research suggests that minor elevations (≤16 ng/mL) of AFP in patients with otherwise pure seminoma may not always indicate hidden nonseminomatous elements 3
• Approximately 2% of seminoma patients may have unspecific mild AFP elevations 4

Treatment Implications

• If AFP is positive in a patient with histologically diagnosed seminoma, the patient should be treated as having nonseminoma 1
• This distinction is critical because nonseminomas are more clinically aggressive than seminomas and require different treatment approaches 1

Monitoring and Follow-up

• In follow-up for seminoma patients, AFP is typically included in the panel of markers monitored, along with hCG and LDH 1
• For patients with advanced seminoma, rising marker levels may be the earliest sign of relapse 1

Pitfalls to Avoid

• Failing to measure AFP before orchiectomy, which complicates interpretation of post-surgical values
• Misinterpreting borderline AFP elevations without considering other clinical factors
• Ignoring an elevated AFP in a patient with histologically diagnosed seminoma, which could lead to inadequate treatment
• Not considering rare cases of false-positive AFP elevations due to liver disease or other non-malignant conditions 2

In clinical practice, the presence of AFP elevation in a patient with testicular cancer is a key factor that guides treatment decisions and should never be overlooked, even when histology suggests pure seminoma.