Identifying signs of lung cancer: Understanding markers and diagnostic tests for non-small cell lung cancer
Non-Small Cell Lung Cancer (NSCLC) is a formidable foe, but understanding its intricacies can help in the battle against it. Tumor markers, specific substances found in higher concentrations in cancer cells, play a crucial role in the diagnosis, treatment, and management of NSCLC.
Common tumor markers for NSCLC include CEA (carcinoembryonic antigen), CYFRA 21-1 (cytokeratin 19 fragment), and PD-L1 (programmed death-ligand 1). These markers are instrumental in helping detect malignant lung lesions, monitoring disease progression, and guiding treatment decisions.
CEA and CYFRA 21-1 are frequently elevated in NSCLC patients and are used clinically for their diagnostic and monitoring capabilities [3]. On the other hand, PD-L1 expression is a critical biomarker for guiding immunotherapy prescriptions, particularly for immune checkpoint inhibitors (ICIs) targeting PD-1/PD-L1. Higher PD-L1 expression correlates with better responses to immunotherapy in NSCLC [2][4].
Molecular markers, such as KRAS mutations and HER2 alterations, help categorize NSCLC molecular subtypes and allow targeted drug therapies to be applied, improving treatment personalization [5]. Other markers like microsatellite instability-high (MSI-H) and immune cell markers like tumor-infiltrating lymphocytes provide additional prognostic and predictive information but are less established in routine NSCLC diagnostics [2].
However, it's essential to note that tumor markers are not a certainty. People may have cancer without notable changes in tumor markers, and some conditions have few reliable tumor markers to check for [6]. Nevertheless, a panel that includes testing for PRL, CEA, and CYFRA21-1 has been found to be relatively sensitive and specific for diagnosing NSCLC compared to testing for individual tumor markers [7].
The three main tumor markers doctors use to diagnose NSCLC are CYFRA21-1, CEA, and SCC-Ag. CYFRA21-1 was the most sensitive single marker for NSCLC according to research from 2017 [8]. Higher levels of CEA and CA125 are often found in adenocarcinoma, higher levels of SCC in squamous tumors, and higher levels of CA125 in large cell lung cancer [9].
Tumor markers may help differentiate between types of lung cancer and subtypes, such as small cell carcinoma or different types of NSCLC. The upper limits for "normal" levels of CEA, CA125, and CA19-9 tumor markers are 5 nanograms (ng) per milliliter (ml), 35 units per ml, and 35 units per ml respectively, as per research from 2024 [10].
In summary, tumor markers, particularly CEA, CYFRA 21-1, and PD-L1, are invaluable tools in the diagnosis, treatment, and management of NSCLC. They aid in detecting malignant lung lesions, monitoring disease progression, and guiding treatment decisions, particularly immunotherapy and targeted therapies. However, it's crucial to remember that tumor markers are not a definitive diagnosis and should be used in conjunction with other tests for comprehensive results.
- Non-Small Cell Lung Cancer (NSCLC) patients often exhibit elevated levels of the tumor markers CEA and CYFRA 21-1, which are clinically useful for diagnosis and monitoring purposes.
- PD-L1 expression is a biomarker critical for guiding immunotherapy prescriptions, particularly for immune checkpoint inhibitors, and higher PD-L1 expression correlates with better responses to immunotherapy in NSCLC.
- Other cancer-related medical conditions such as small cell carcinoma or different types of NSCLC can be differentiated using tumor markers like CEA, CA125, and CA19-9.
- Tumor markers, including CEA, CYFRA 21-1, and PD-L1, are essential for health-and-wellness management, as they help diagnose, treat, and manage chronic diseases like NSCLC and guide therapies and treatments for these conditions.
