What Is Nonsmall Cell Lung Cancer?
Nonsmall cell lung cancer, or NSCLC, is the most common form of lung cancer, making up roughly 85% of all cases. It grows and spreads more slowly than the small cell type, and it includes several distinct subtypes. Understanding the specific diagnosis is the first step toward a treatment plan that fits the individual.
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Main Subtypes of NSCLC
NSCLC is not a single disease. The three major subtypes are named for the cells where the cancer originates, and each may respond differently to treatment.
- Adenocarcinoma: The most common subtype, often found in the outer parts of the lung. It occurs in both smokers and nonsmokers and includes many genetic mutations that can be targeted with therapy.
- Squamous Cell Carcinoma: Typically linked to smoking, it tends to start in the central airways near the bronchi.
- Large Cell Carcinoma: A less common subtype that can appear anywhere in the lung and may grow quickly.
How NSCLC Is Diagnosed
Diagnosis usually starts with imaging, such as a chest X-ray or CT scan, when symptoms like a persistent cough, shortness of breath, or unexplained weight loss appear. A biopsy is needed to confirm NSCLC and identify the subtype. Pathologists examine the tissue under a microscope, and molecular testing may be done to look for specific gene changes, such as EGFR, ALK, or ROS1 alterations, that guide treatment choices.
Staging NSCLC
Staging describes how far the cancer has spread and is based on the size of the tumor, involvement of lymph nodes, and whether it has reached distant organs. The system most commonly used is the TNM classification, which stands for Tumor, Nodes, and Metastasis.
| Stage | What It Means |
|---|---|
| Stage I | Tumor is small and contained to the lung; no lymph node involvement. |
| Stage II | Tumor may be larger or has spread to nearby lymph nodes within the lung. |
| Stage III | Cancer has spread to lymph nodes in the chest but not to distant sites. |
| Stage IV | Cancer has metastasized to distant organs such as the liver, bones, or brain. |
Treatment Options for NSCLC
Treatment depends on the stage, subtype, overall health, and molecular features of the tumor. Options are often used in combination.
Surgery
For early-stage NSCLC, surgery to remove the tumor and part of the lung is often the first choice. Procedures range from a wedge resection to a lobectomy or pneumonectomy, depending on the tumor's size and location.
Radiation Therapy
Radiation can be used before surgery to shrink a tumor, after surgery to kill remaining cancer cells, or as the main treatment for patients who cannot have surgery. Stereotactic body radiotherapy offers a precise, high-dose approach for early-stage tumors in patients who are not surgical candidates.
Chemotherapy
Chemotherapy uses drugs to kill rapidly dividing cells throughout the body. It may be given before surgery, after surgery, or as a primary treatment for advanced disease.
Targeted Therapy
Targeted drugs attack specific genetic changes in cancer cells. For example, EGFR inhibitors work for tumors with EGFR mutations, and ALK inhibitors are used for ALK rearrangements. These therapies often have fewer side effects than chemotherapy.
Immunotherapy
Immunotherapy helps the body's immune system recognize and attack cancer cells. Checkpoint inhibitors such as pembrolizumab and nivolumab are used for advanced NSCLC, often in combination with chemotherapy or as a first-line treatment when the tumor expresses PD-L1.
Prognosis and What Patients Can Do
The outlook for NSCLC varies widely by stage at diagnosis and the presence of treatable mutations. Early-stage disease has a much better prognosis than advanced disease, and the availability of targeted therapies and immunotherapies has improved survival for many patients. Quitting smoking, following the treatment plan closely, and attending regular follow-up visits are among the most impactful steps a patient can take.