Lung Cancer: Types, Causes, Symptoms & Treatment

Lung cancer is the name giving to cancers that start in your lungs usually in the airways (bronchi or bronchioles) or small air sacs (alveoli). Cancers that start in other places and move to your lungs are usually named for where they start (your healthcare provider may refer to this as cancer that’s metastatic to your lungs).

Lung cancer occur as a disease which is caused by uncontrolled cell division in your lungs. Your cells divide and make more copies of themselves as a part of their normal function. But sometimes, they get changes (mutations) that cause them to keep making more of themselves when they shouldn’t. Damaged cells dividing uncontrollably create masses, or tumors of tissue that eventually keep your organs from working properly.

People who smoke have the greatest risk of lung cancer, though lung cancer can also occur in people who have never smoked. The risk of lung cancer increases with the length of time and number of cigarettes you’ve smoked. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer.

Symptoms of lung cancer

The early stages of lung cancer don’t always cause symptoms. When early symptoms do occur, they can include signs such as shortness of breath, along with unexpected symptoms, such as back pain.

Back pain can occur when tumors cause pressure in your lungs or when they spread to your spinal cord and ribs.

Other early signs of lung cancer may include:

• a lingering or worsening cough
• coughing up phlegm or blood
• chest pain that worsens when you breathe deeply, laugh, or cough
• hoarseness
• wheezing
• weakness and fatigue
• loss of appetite and weight loss
• recurrent respiratory infections such as pneumonia or bronchitis

Additional symptoms of lung cancer depend on where new tumors form. Not everyone with late-stage lung cancer will experience every symptom.

Late-stage symptoms might include:

• lumps in the neck or collarbone
• bone pain especially in the back, ribs, or hips
• headaches
• dizziness
• balance issues
• numbness in arms or legs
• yellowing of skin and eyes (jaundice)
• drooping of one eyelid and shrunken pupils
• lack of perspiration on one side of the face
• shoulder pain
• swelling of the face and upper body

Additionally, lung cancer tumors can sometimes release a substance similar to hormones, leading to a wide variety of symptoms known as paraneoplastic syndrome. Symptoms include:

• muscle weakness
• nausea and vomiting
• high blood sugar
• high blood pressure
• confusion
• seizures

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Causes of lung cancer

Smoking causes the majority of lung cancers both in smokers and in people exposed to secondhand smoke. But lung cancer also occurs in people who never smoked and in those who never had prolonged exposure to secondhand smoke. In these cases, there may be no clear cause of lung cancer.

Doctors believe smoking causes lung cancer by damaging the cells that line the lungs. When you inhale cigarette smoke, which is full of cancer-causing substances (carcinogens), changes in the lung tissue begin almost immediately.

At first your body may be able to repair this damage. But with each repeated exposure, normal cells that line your lungs are increasingly damaged. Over time, the damage causes cells to act abnormally and eventually cancer may develop.

Types of lung cancer

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) 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) 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 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.

Stages of lung cancer

Cancer stages tell how far cancer has spread and help guide treatment. 

The chance of successful or curative treatment is much higher when lung cancer is diagnosed and treated early. Because lung cancer may not cause obvious symptoms in the earlier stages, diagnosis often comes after it has spread.

Non-small cell lung cancer (NSCLC) stages:

• Stage 1: Cancer is found in the lung, but it has not spread outside the lung.
• Stage 2: Cancer is found in the lung and nearby lymph nodes.
• Stage 3: Cancer is in the lung and lymph nodes in the middle of the chest.
• Stage 3A: Cancer is found in lymph nodes, but only on the same side of the chest where cancer first started growing.
• Stage 3B: Cancer has spread to lymph nodes on the opposite side of the chest or to lymph nodes above the collarbone.
• Stage 4: Cancer has spread to both lungs, into the area around the lungs, or to distant organs.

Small-cell lung cancer (SCLC) stages:

There are two stages of SCLC, limited and extensive. In the limited stage, cancer is found in only one lung or nearby lymph nodes on the same side of the chest.

The extensive stage means cancer has spread:

• throughout one lung
• to the opposite lung
• to lymph nodes on the opposite side
• to fluid around the lung
• to bone marrow
• to distant organs

About 2 out of 3 people with SCLC are already in the extensive stage when their cancer is diagnosed.

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Risk factors of lung cancer

A number of factors may increase your risk of lung cancer. Some risk factors can be controlled, for instance, by quitting smoking. And other factors can’t be controlled, such as your family history.

Risk factors for lung cancer include:

• Smoking. Your risk of lung cancer increases with the number of cigarettes you smoke each day and the number of years you have smoked. Quitting at any age can significantly lower your risk of developing lung cancer.
• Exposure to secondhand smoke. Even if you don’t smoke, your risk of lung cancer increases if you’re exposed to secondhand smoke.
• Previous radiation therapy. If you’ve undergone radiation therapy to the chest for another type of cancer, you may have an increased risk of developing lung cancer.
• Exposure to radon gas. Radon is produced by the natural breakdown of uranium in soil, rock and water that eventually becomes part of the air you breathe. Unsafe levels of radon can accumulate in any building, including homes.
• Exposure to asbestos and other carcinogens. Workplace exposure to asbestos and other substances known to cause cancer — such as arsenic, chromium and nickel — can increase your risk of developing lung cancer, especially if you’re a smoker.
• Family history of lung cancer. People with a parent, sibling or child with lung cancer have an increased risk of the disease.

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Complications of lung cancer

Lung cancer can lead to complications. These include:

• High risk of infection: People with lung cancer are at an increased risk of pneumonia, bronchitis, and other infections.
• Facial swelling: Tumors in your lungs can restrict blood flow to your upper body and result in facial swelling.
• Loss of lung function: Shortness of breath, difficulty breathing, and other symptoms of reduced lung function can occur in lung cancer patients.
• Blood clots: People with lung cancer are at a higher risk of clots, especially in their lower legs.
• Spitting up blood: Irritation in airways or from tumors can result in spitting up blood.
• Increased calcium in blood: Sometimes, lung cancer can result in hypercalcemia, or increased calcium in your blood.
• Spinal compression: Tumors can press on the spine and cause pain, weakness, and trouble walking.
• Heart blockage: Tumors in your lungs can compress heart vessels and lead to multiple serious heart conditions.
• Nerve pain: Tumors can result in nerve pain along with numbness, tingling, and weakness.
• Trouble swallowing: Lung cancer can spread to your esophagus and cause trouble swallowing.

Prevention of lung cancer

There’s no sure way to prevent lung cancer, but you can reduce your risk if you:

• Don’t smoke or quit smoking if you do. Your risk of lung cancer starts coming down within five years of quitting.
• Avoid second hand smoke and other substances that can harm your lungs.
• Eat a healthy diet and maintain a weight that’s healthy for you. Some studies suggest that eating fruits and vegetables (two to six-and-a-half cups per day) can help reduce your risk of cancer.
• Get screened for lung cancer if you’re at high risk.

Diagnosis of lung cancer

People with an increased risk of lung cancer may consider annual lung cancer screening using low-dose CT scans. Lung cancer screening is generally offered to older adults who have smoked heavily for many years or who have quit in the past 15 years.

Discuss your lung cancer risk with your doctor. Together you can decide whether lung cancer screening is right for you.

Tests to diagnose lung cancer

If there’s reason to think that you may have lung cancer, your doctor can order a number of tests to look for cancerous cells and to rule out other conditions. Tests may include:

• Imaging tests. An X-ray image of your lungs may reveal an abnormal mass or nodule. A CT scan can reveal small lesions in your lungs that might not be detected on an X-ray.
• Sputum cytology. If you have a cough and are producing sputum, looking at the sputum under the microscope can sometimes reveal the presence of lung cancer cells.
• Tissue sample (biopsy). A sample of abnormal cells may be removed in a procedure called a biopsy.

Your doctor can perform a biopsy in a number of ways, including bronchoscopy, in which your doctor examines abnormal areas of your lungs using a lighted tube that’s passed down your throat and into your lungs.

Mediastinoscopy, in which an incision is made at the base of your neck and surgical tools are inserted behind your breastbone to take tissue samples from lymph nodes is also an option.

Another option is needle biopsy, in which your doctor uses X-ray or CT images to guide a needle through your chest wall and into the lung tissue to collect suspicious cells.A biopsy sample may also be taken from lymph nodes or other areas where cancer has spread, such as your liver.

Careful analysis of your cancer cells in a lab will reveal what type of lung cancer you have. Results of sophisticated testing can tell your doctor the specific characteristics of your cells that can help determine your prognosis and guide your treatment.

Once your lung cancer has been diagnosed, your doctor will work to determine the extent (stage) of your cancer. Your cancer’s stage helps you and your doctor decide what treatment is most appropriate.

Staging tests may include imaging procedures that allow your doctor to look for evidence that cancer has spread beyond your lungs. These tests include CT, MRI, positron emission tomography (PET) and bone scans. Not every test is appropriate for every person, so talk with your doctor about which procedures are right for you.

The stages of lung cancer are indicated by Roman numerals that range from 0 to IV, with the lowest stages indicating cancer that is limited to the lung. By stage IV, the cancer is considered advanced and has spread to other areas of the body.

Treatment of lung cancer

Treatments for lung cancer are designed to get rid of cancer in your body or slow down its growth. Treatments can remove cancerous cells, help to destroy them or keep them from multiplying or teach your immune system to fight them. Some therapies are also used to reduce symptoms and relieve pain.

Your treatment will depend on the type of lung cancer you have, where it is, how far it’s spread and many other factors.

Lung cancer treatments include surgery, radiofrequency ablation, radiation therapy, chemotherapy, targeted drug therapy and immunotherapy.

• Surgery. NSCLC that hasn’t spread and SCLC that’s limited to a single tumor can be eligible for surgery. Your surgeon might remove the tumor and a small amount of healthy tissue around it to make sure they don’t leave any cancer cells behind. Sometimes they have to remove all or part of your lung (resection) for the best chance that the cancer won’t come back.
• Radiofrequency ablation. NSCLC tumors near the outer edges of your lungs are sometimes treated with radiofrequency ablation (RFA). RFA uses high-energy radio waves to heat and destroy cancer cells.
• Radiation therapy. radiation uses high energy beams to kill cancer cells. It can be used by itself or to help make surgery more effective. Radiation can also be used as palliative care, to shrink tumors and relieve pain. It’s used in both NSCLC and SCLC.
• Chemotherapy. chemotherapy is often a combination of multiple medications designed to stop cancer cells from growing. It can be given before or after surgery or in combination with other types of medication, like immunotherapy. Chemotherapy for lung cancer is usually given through an IV.
• Targeted drug therapy. In some people with NSCLC, lung cancer cells have specific changes (mutations) that help the cancer grow. Special drugs target these mutations to try to slow down or destroy cancer cells. Other drugs, called angiogenesis inhibitors, can keep the tumor from creating new blood vessels, which the cancer cells need to grow.
• Immunotherapy. Our bodies usually recognize cells that are damaged or harmful and destroy them. Cancer has ways to hide from the immune system to keep from being destroyed. Immunotherapy reveals cancer cells to your immune system so your own body can fight cancer.
• palliative care. Some lung cancer treatments are used to relieve symptoms, like pain and difficulty breathing. These include therapies to reduce or remove tumors that are blocking airways, and procedures to remove fluid from around your lungs and keep it from coming back.

Your provider can prescribe medications to help manage your symptoms or side effects of treatment. A palliative care specialist or a dietician can help you manage pain or other symptoms and improve your quality of life while you’re in treatment.

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