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Overview

Lung cancer is the leading cause of cancer-related deaths globally, with non-small cell lung cancer (NSCLC) accounting for approximately 80–85% of cases. While early detection significantly improves treatment outcomes and prognosis, the majority of patients are unfortunately diagnosed at an advanced stage.

Among the various blood tests used to support clinical management, Cyfra 21-1 is a vital biomarker, particularly valuable for NSCLC, especially the squamous cell carcinoma subtype.

What is Cyfra 21-1?

• Cyfra 21-1 is a soluble fragment of Cytokeratin 19, a structural protein found in epithelial cells.

• When lung cancer cells, specifically squamous cell carcinomas, undergo damage or rapid turnover, Cytokeratin 19 is released into the bloodstream, causing Cyfra 21-1 levels to rise.

• Consequently, measuring serum Cyfra 21-1 levels serves as a clinical window into the disease status.

Normal Reference Ranges

• Healthy Individuals: Cyfra 21-1 is typically < 3.3 ng/mL.

• Note: Reference values may vary slightly depending on the specific laboratory and testing equipment used.

Causes of Elevated Cyfra 21-1

1. Malignancies

• Non-small cell lung cancer (NSCLC): The most significant association, particularly squamous cell carcinoma.

• Other cancers: Esophageal, bladder, thyroid, and cervical cancer.

2. Benign Conditions

• Chronic lung diseases: Tuberculosis, pneumonia, or pulmonary fibrosis.

• Chronic kidney failure.

• Liver disease or cirrhosis.

👉 While Cyfra 21-1 is not entirely exclusive to lung cancer, a marked elevation is strongly indicative of NSCLC.

Clinical Significance

1. Screening

• Cyfra 21-1 is not recommended for general population screening.

• Low-dose CT scans (LDCT) remain the preferred method for high-risk individuals (such as heavy smokers over age 50).

2. Diagnosis

• Cyfra 21-1 acts as a supportive diagnostic tool for NSCLC.

• It offers a sensitivity of 50–70% and a high specificity of 85–95% for squamous cell carcinoma.

• Diagnostic accuracy improves significantly when combined with other markers like CEA, NSE, or ProGRP.

3. Prognosis

• Higher Cyfra 21-1 levels correlate with a poorer prognosis.

• Levels exceeding 10 ng/mL often suggest tumor progression, metastasis, or an advanced stage.

4. Post-Treatment Monitoring

This is the most critical application of the test.

• Levels typically decrease following successful surgery or chemotherapy.

• A subsequent rise in Cyfra 21-1 may signal disease recurrence or progression.

• Regular monitoring allows physicians to assess treatment response in real-time.

Limitations of Cyfra 21-1 test

• Non-specific: Levels can rise due to benign lung or kidney conditions.

• No substitute for biopsy: Lung tissue biopsy remains the gold standard for a definitive diagnosis.

• Low sensitivity in SCLC: It is less effective for small-cell lung cancer (SCLC), requiring coordination with markers like NSE or ProGRP.

When is a Cyfra 21-1 Test needed?

• For diagnosed NSCLC patients: To track treatment efficacy and detect early relapse.

• Pre-intervention: To establish a baseline for severity and prognosis.

• Post-treatment surveillance: Scheduled periodic testing to monitor the disease course.

Note: Cyfra 21-1 should not be used as the sole diagnostic criteria for healthy individuals.

Procedure of a Cyfra 21-1 test

1. A standard venous blood draw; no fasting is required.

2. Samples are analyzed using immunoassay techniques.

3. Results are generally available within 1–2 business days.

Conclusion

Cyfra 21-1 is a key biomarker for managing non-small cell lung cancer, particularly squamous cell carcinoma. It provides essential data for diagnosis, prognosis, and post-treatment monitoring.

However, it must be used in conjunction with bronchoscopy, imaging, and biopsies to ensure an accurate clinical decision.

FAQ

1. At what level is Cyfra 21-1 considered abnormal?

Levels above 3.3 ng/mL are elevated. Levels exceeding 10 ng/mL indicate a significantly higher risk of lung malignancy.

2. Is this test used for routine lung cancer screening?

No. Low-dose CT scans are the gold standard for screening high-risk groups.

3. Does a high Cyfra 21-1 level always mean lung cancer?

Not necessarily. Chronic lung infections or kidney failure can also cause elevated results.

4. When should I re-test after lung cancer treatment?

Typically 4–6 weeks post-treatment to evaluate response, followed by checks every 2–3 months as directed by your oncologist.

5. Do I need to fast before the test?

No. It is a simple blood test that can be performed at any time of day.

To schedule a Cyfra 21-1 test and lung health consultation at DYM Medical Center Vietnam, please contact us:

• DYM Medical Center Saigon: Room B101-B103, Basement 1, mPlaza Saigon Building, No. 39 Le Duan, Sai Gon Ward, Ho Chi Minh City

• DYM Medical Center Phu My Hung: Room 3A01, 3A Floor, The Grace Building, 71 Hoang Van Thai Street, Tan My Ward, Ho Chi Minh City

• DYM Medical Center Hanoi: B1 Basement, Epic Tower, Alley 19 Duy Tan, Cau Giay Ward, Ha Noi

• Hotline: 1900 29 29 37