More than half of lung cancer patients die within one year of diagnosis without treatment. For any hope of survival, medical or surgical treatment is necessary.
Life expectancy after being diagnosed with lung cancer depends on the stage of the cancer at the time of diagnosis, as well as a person’s age, their overall health, and whether they have other medical conditions. Once the cancer has spread (metastasized) to other parts of the body the survival rate is much lower. Lung cancer is often not detected until it has spread.
Life expectancy for cancers is typically expressed as a 5-year survival rate (the percent of patients who will be alive 5 years after diagnosis). Overall, the 5-year survival rate for lung cancer is lower than other cancers, at 18.6%. The lung cancer 5-year survival rate is 56% when the cancer is detected while the disease is still localized in the lungs. Once the lung cancer has spread, the 5-year survival rate drops to just 5%.
There are many cancers that affect the lungs, but we usually use the term “lung cancer” for two main kinds: non-small cell lung cancer and small cell lung cancer.
Non-small cell lung cancer (NSCLC)
Non-small cell lung cancer (NSCLC) is the most common type of lung cancer. It accounts for over 80% of lung cancer cases. Common types include adenocarcinoma and squamous cell carcinoma. Adenosquamous carcinoma and sarcomatoid carcinoma are two less common types of NSCLC.
Small cell lung cancer (SCLC)
Small cell lung cancer (SCLC) grows more quickly and is harder to treat than NSCLC. It’s often found as a relatively small lung tumor that’s already spread to other parts of your body. Specific types of SCLC include small cell carcinoma (also called oat cell carcinoma) and combined small cell carcinoma.
Other types of cancer in the lungs
Other types of cancer can start in or around your lungs, including lymphomas (cancer in your lymph nodes), sarcomas (cancer in your bones or soft tissue) and pleural mesothelioma (cancer in the lining of your lungs). These are treated differently and usually aren’t referred to as lung cancer.
Lung cancer is caused by cells that keep dividing even though they shouldn’t. While cell division is a normal process, all cells have a built-in off switch that keeps them from dividing into more cells (senescence) or causes them to die off (apoptosis) when necessary. The off switch is triggered when a cell has divided too many times or has too many changes (mutations).
Cancer cells are normal cells in your body that have gained mutations that remove the off switch. Cells keep multiplying, unchecked, and interfere with your normal cells. Cancer cells can get into your bloodstream or lymph nodes and move to other places in your body, spreading the damage.
We’re not sure what causes these changes that lead to cancer in some people and not others, but certain factors, including smoking tobacco products, can put you at higher risk for damage to your cells that can cause lung cancer.
While there are many factors that can increase your risk of lung cancer, smoking any kind of tobacco products, including cigarettes, cigars or pipes is the biggest single risk factor. Experts estimate that 80% of lung cancer deaths are smoking-related.
Other risk factors include:
- Being exposed to secondhand tobacco smoke.
- Being exposed to harmful substances, like air pollution, radon, asbestos, uranium, diesel exhaust, silica, coal products and others.
- Having previous radiation treatments to your chest (for instance, for breast cancer or lymphoma).
- Having a family history of lung cancer.
Most lung cancer symptoms look similar to other, less serious illnesses. Many people don’t have symptoms until the disease is advanced, but some people have symptoms in the early stages. For those who do experience symptoms, it may only be one or a few of these:
- A cough that doesn’t go away or gets worse over time.
- Trouble breathing or shortness of breath (dyspnea).
- Chest pain or discomfort.
- Wheezing.
- Coughing up blood (hemoptysis).
- Hoarseness.
- Loss of appetite.
- Unexplained weight loss.
- Unexplained fatigue (tiredness).
- Shoulder pain.
- Swelling in the face, neck, arms or upper chest (superior vena cava syndrome).
- Small pupil and drooping eyelid in one eye with little or no sweating on that side of your face (Horner’s syndrome).
Diagnosing lung cancer can be a multi-step process. Your first visit to a healthcare provider will usually involve them listening to your symptoms, asking you about your health history and performing a physical exam (like listening to your heart and lungs). Since lung cancer symptoms are similar to many other, more common illnesses, you provider may start by getting blood tests and a chest X-ray.
If your provider suspects you could have lung cancer, your next steps in diagnosis would usually involve more imaging tests, like a CT scan, and then a biopsy. Other tests include using a PET/CT scan to see if cancer has spread, and tests of cancerous tissue from a biopsy to help determine the best kind of treatment.
Cancer is usually staged based on the size of the initial tumor, how far or deep into the surrounding tissue it goes, and whether it’s spread to lymph nodes or other organs. Each type of cancer has its own guidelines for staging.
Lung cancer staging
Each stage has several combinations of size and spread that can fall into that category. For instance, the primary tumor in a Stage III cancer could be smaller than in a Stage II cancer, but other factors put it at a more advanced stage. The general staging for lung cancer is:
- Stage 0 (in-situ): Cancer is in the top lining of the lung or bronchus. It hasn’t spread to other parts of the lung or outside of the lung.
- Stage I: Cancer hasn’t spread outside the lung.
- Stage II: Cancer is larger than Stage I, has spread to lymph nodes inside the lung, or there’s more than one tumor in the same lobe of the lung.
- Stage III: Cancer is larger than Stage II, has spread to nearby lymph nodes or structures or there’s more than one tumor in a different lobe of the same lung.
- Stage IV: Cancer has spread to the other lung, the fluid around the lung, the fluid around the heart or distant organs.
