Gagandeep Brar, MD, is a board-certified hematologist and medical oncologist in Los Angeles, California.
Non-small cell lung cancer (NSCLC) is the most common form of lung cancer, accounting for 80 to 85% of all cases of lung cancer. There are different stages of NSCLC, ranging from 0 to 4; higher-numbered stages indicate the cancer has spread further and tumors are larger.
Symptoms and treatment options depend on the stage of your lung cancer along with what type of NSCLC you're diagnosed with. There are three primary types: adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.
Lung cancer remains a difficult disease to completely overcome. However, improvements in screening are enabling doctors to catch lung cancer earlier than in previous generations, and advancements in treatments have been improving survival rates for all stages of NSCLC.
Smoking is still the leading cause of non-small cell lung cancer, but there are other significant risk factors. Secondhand smoke accounts for approximately 7,330 deaths from lung cancer per year. Radon exposure is the leading cause of lung cancer in nonsmokers. Family history, occupational exposures, lung disease (such as COPD), and air pollution also contribute.
Staging can help determine the spread of the disease and inform treatment.
Stage 0/In situ: Known as precancer. Typically no symptoms.
Stage 1: Tumor is invasive but has not spread to lymph nodes.
Stage 2: Cancer is localized to one lung/lymph nodes on that side of the lung.
Stage 3: Cancer is larger, or has spread to different lymph nodes than stage 2 or to nearby tissues.
Stage 4: Metastatic; cancer has spread to the other lung, further in the affected lung, or other parts of the body.
In general, non-small cell lung cancer may be curable if it is localized (up to stage 3). Unfortunately, although cure is possible in the majority of patients with stage 0, at present, only a minority of patients with stage 3 are cured. Many treatment options are available, including local and systemic methods. Treatments are most successful when cancer is detected early. However, not all types of NSCLC show early symptoms, making diagnosis difficult.
Roughly 50% of cases of NSCLC are adenocarcinomas of the lung, in which tumors start to develop in the outer portion of the lungs. Symptoms are less obvious than in other forms of lung cancer, and are fairly general at first, manifesting as fatigue, chest pain, and subtle shortness of breath. In later stages, chronic cough and bloody sputum are common.
A high-energy radiation from X-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. For NSCLC, radiation can be used in one of four ways: adjuvant therapy (treating remaining cancer cells post-surgery), neoadjuvant therapy (decreasing tumor size presurgery), palliative treatment (decreasing pain in cancers that cannot be cured), or curative treatment (as an alternative to surgery).
A much less common form of lung cancer than NSCLC, accounting for around 15% of all cases.1 Small cell carcinoma is highly malignant (aggressive) and is often only diagnosed after the cancer has spread and surgery is no longer possible. Small cell carcinoma is mostly found in smokers.
Another form of NSCLC, squamous cell carcinoma forms in the tissues that line the air passages in the lungs. Because larger airways like the bronchi are affected, usually, symptoms manifest earlier than in adenocarcinoma. Squamous cell carcinoma is closely tied to smoking, and it is the most common cause of Pancoast syndrome (cancers forming near the top of the lungs).
A classification system used to stage cancer spread/severity.
TNM takes into account the size of the main tumor (T), the number of lymph nodes that have been impacted by cancer (N), and whether the cancer has metastasized (spread) to other organs/tissues (M). NSCLC stages range from 0 to 4, with 4 being the most advanced.
American Cancer Society. What is lung cancer? Updated October 1, 2019.
U.S. Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General. 2014.
American Cancer Society. Signs and symptoms of lung cancer. Updated October 1, 2019
Wang Y, Pang Z, Chen X, Yan T, Liu J, Du J. Development and validation of a prognostic model of resectable small-cell lung cancer: a large population-based cohort study and external validation. J Transl Med. 2020;18(1):237. doi:10.1186/s12967-020-02412-x
National Cancer Institute. Cancer staging. Updated March 9, 2015.
American Cancer Society. Treatment choices for non-small cell lung cancer, by stage. Updated October 7, 2020.
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