Unit Converter
Squamous cell carcinoma (SCC)
(Serum Tumor Marker for Squamous Cell Malignancies - Used for Monitoring, Prognosis & Recurrence Detection)
Synonyms
- SCC
- SCC antigen
- SCCA
- TA-4 antigen
- Squamous cell carcinoma antigen
- Serpin B3/B4 (molecular family)
Units of Measurement
- ng/mL
- ng/dL
- ng/100 mL
- ng%
- ng/L
- µg/L
Unit Conversions
1 ng/mL=1 µg/L1\ \text{ng/mL} = 1\ \text{µg/L}1 ng/mL=1 µg/L 1 ng/mL=1000 ng/L1\ \text{ng/mL} = 1000\ \text{ng/L}1 ng/mL=1000 ng/L 1 ng/mL=100 ng/dL1\ \text{ng/mL} = 100\ \text{ng/dL}1 ng/mL=100 ng/dL \text{ng%} = \text{ng/dL}
Description
SCC (Squamous Cell Carcinoma Antigen) is a serine protease inhibitor (serpin) family protein released from:
- Squamous epithelial cells
- Squamous cell tumors
It is primarily used as a tumor marker for:
- Cervical cancer
- Head & neck squamous cancers
- Lung squamous carcinoma
- Esophageal squamous carcinoma
- Anal canal cancers
SCC is not used to diagnose cancer but is helpful for monitoring progression, treatment response, and recurrence.
Physiological Role
- Regulates cell differentiation
- Helps control protease activity
- Linked to epithelial integrity
However, its elevation in serum mainly reflects tumor cell turnover or release from damaged squamous cells.
Clinical Significance
HIGH SCC Ag
1. Squamous Cell Carcinomas
Elevated in:
- Cervical carcinoma (especially stages IIB–IV)
- Head & neck squamous cancer
- Lung squamous carcinoma
- Esophageal SCC
- Anal SCC
- Skin SCC metastasis
Higher levels correlate with:
- Larger tumor burden
- Advanced stage
- Lymph node involvement
- Recurrence
- Poor prognosis
Typical Levels
| Condition | SCC Ag Level |
| Healthy | < 2.0 ng/mL |
| Localized SCC | 2–5 ng/mL |
| Advanced SCC | 5–15 ng/mL |
| Metastatic/recurrence | >15 ng/mL |
NON-MALIGNANT Causes of High SCC
Important for interpretation:
- Chronic kidney disease (reduced clearance)
- Psoriasis
- Eczema / atopic dermatitis
- Asthma
- Sarcoidosis
- Tuberculosis
- Pelvic inflammatory disease
- Benign esophageal disease
- Severe skin disorders
Always interpret SCC Ag within complete clinical context.
LOW / NORMAL SCC
- Normal individuals typically have <2.0 ng/mL
- Normal SCC does not rule out malignancy (low sensitivity for early cancers)
Reference Intervals
(Tietz 8E + Mayo + ARUP)
Serum SCC Ag
- < 2.0 ng/mL → Normal
- 2.0–4.0 ng/mL → Borderline
- > 4.0 ng/mL → Elevated (evaluate malignancy or benign causes)
- > 10 ng/mL → Suggestive of advanced disease or recurrence
- > 15–20 ng/mL → Strongly predictive of metastatic SCC
Diagnostic Uses
1. Monitoring Cervical Cancer
- Assess response to chemoradiation
- Detect local recurrence
- Evaluate residual disease
- Guide prognosis
2. Head & Neck Cancer
SCC Ag correlates with tumor size, node involvement.
3. Lung Squamous Carcinoma
Useful in monitoring treatment response.
4. Esophageal Squamous Carcinoma
5. Anal & Vulvar SCC
6. Prognostic Marker
Higher SCC prior to therapy = worse outcomes.
Analytical Notes
- Measured via immunoassays (CLIA, ELISA).
- Not a screening test for general population.
- Serum should be promptly separated to avoid protein degradation.
- Important to ensure consistency of assay manufacturer during follow-up.
Clinical Pearls
- SCC Ag correlates with tumor burden - good for monitoring but poor for early detection.
- High levels after treatment usually indicate recurrence before imaging shows changes.
- Renal impairment may cause falsely high SCC - check eGFR.
- In cervical cancer, SCC Ag is often combined with HPV-DNA, imaging, and clinical staging.
- Not specific - always confirm with imaging and pathology.
Interesting Fact
SCC antigen belongs to the serpin B3/B4 family, discovered originally as TA-4, a squamous-cell–associated protein in cervical carcinoma tissues.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Tumor Markers
- NCCN Guidelines - Cervical, Head & Neck, Lung, Esophageal Cancers
- ESMO Clinical Practice Guidelines
- Mayo Clinic Laboratories - SCC Antigen
- ARUP Consult - Tumor Markers
- WHO Cervical Cancer Screening Resources