SCC (Squamous Cell Carcinoma Antigen) Test: Uses & Levels

What Is Squamous Cell Carcinoma Antigen (SCC)?

When a patient comes to my clinic after treatment for cervical, lung, or head and neck cancer, one of the first questions they ask is about surveillance. The SCC antigen blood test offers one piece of that puzzle — but it's never the whole story. SCC, or Squamous Cell Carcinoma Antigen, is a tumour marker produced by cells that line the surfaces of organs, particularly those that are squamous (flat and scale-like).

In healthy individuals, very small amounts of this protein circulate in the bloodstream. However, when squamous cell cancers grow, they often release higher quantities into the blood, making SCC a useful tool for monitoring disease activity over time.

Why Is the SCC Test Ordered?

The SCC test is not a screening tool for the general population. I typically order it for patients already diagnosed with squamous cell cancers, especially:

• Cervical cancer (most common indication)
• Non–small cell lung cancer (squamous subtype)
• Head and neck cancers (oral, laryngeal, pharyngeal)
• Oesophageal squamous cell carcinoma
• Anal and vulvar cancers

Serial measurements help me assess treatment response — for example, a falling SCC level after radiation or chemotherapy suggests the tumour is shrinking. A rising level may indicate recurrence before symptoms appear.

Normal Reference Ranges for SCC

Ranges may vary slightly between labs. Always interpret the result alongside the reference range provided on your report. There is no significant gender difference in baseline SCC levels, though smokers — regardless of gender — tend to have higher baseline readings.

What Does a High SCC Level Mean?

An elevated SCC antigen is not a definitive diagnosis of cancer. In my practice, I always consider the full clinical picture. Potential causes of a raised SCC include:

Cancers

• Squamous cell carcinoma of the cervix, lung, head and neck, oesophagus, or anus
• Large tumour burden or metastatic disease often correlates with higher levels

Benign Conditions

• Psoriasis, eczema, and other inflammatory skin diseases
• Chronic kidney disease or renal failure (reduced clearance)
• Liver cirrhosis
• Benign lung diseases like pneumonia or tuberculosis
• Pregnancy — levels can rise slightly due to hormonal changes

Technical Artifacts

• Haemolysis of the blood sample
• Contamination with sweat or skin cells during collection (rare)

Can SCC Be Used to Diagnose Cancer?

No — I strongly advise my patients not to rely on a single SCC value for diagnosis. Its primary role is monitoring, not detection. False positives are common in benign inflammatory states, and false negatives occur in early-stage disease. Tissue biopsy remains the gold standard for diagnosis.

SCC During Pregnancy

Pregnancy can modestly raise SCC levels due to desquamation of cervical epithelium and hormonal shifts. In my experience, values up to 2.0 ng/mL are not unusual in the second and third trimesters. This must be factored in when monitoring a pregnant woman with a history of cervical cancer.

Limitations of the SCC Test

The test has moderate sensitivity and specificity. A normal SCC does not rule out cancer, and a high level does not prove recurrence. I always combine SCC with imaging (CT, MRI, PET) and clinical examination. Also, not all squamous cell cancers produce SCC — for example, skin squamous cell carcinomas rarely cause elevated blood levels.

Final Thoughts from the Clinic

When my patients receive an unexpected SCC result, we sit down and go through the numbers together. I explain that this marker is a clue, not a verdict. Used correctly — in serial measurements, with proper context — it can be an invaluable guide in the journey through cancer treatment and survivorship.