Lung cancer is one of the most common forms of cancer in the world. In the United States, lung cancer is the leading cause of cancer-related deaths, responsible for more deaths than breast, colon, ovarian, and prostate cancers combined.

While lung cancer refers to any form of cancer originating in the lungs, the disease can affect any of the tissues in and around the lungs. This means that there are several different types of lung cancer to be diagnosed with, each with its own symptoms, staging, and treatment plans. Doctors generally separate lung cancers into two major types: non-small cell lung cancer and small cell lung cancer. Learn more about the different kinds of lung cancer below.

Non-Small Cell Lung Cancers

Non-small cell lung cancer is an umbrella term referring to a handful of subtypes of lung cancer that have similar prognoses and treatments. Non-small cell lung cancer comprises about 80 to 85 percent of all lung cancers. The three main types of non-small cell lung cancer are adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.

Adenocarcinoma

Adenocarcinoma is the most common lung cancer in the United States. Adenocarcinoma is a type of cancer affecting the cells in glandular tissue responsible for secreting mucus. While it is the most common lung cancer among non-smokers, adenocarcinoma in the lungs mainly occurs in current or former smokers.

Adenocarcinoma is more common in the outer areas of the lungs, though it can potentially appear anywhere in the lungs. Thankfully, it is more likely than other kinds of lung cancer to be found before it spreads. Adenocarcinoma in situ, a subtype of adenocarcinoma that was previously known as bronchioloalveolar carcinoma, generally has a more positive outlook than other types of lung cancer.

Squamous Cell Carcinoma

Squamous cells refer to the thin, flat cells that make up the tissue of the epidermis (the uppermost layer of skin) as well as the lining of hollow organs and the respiratory and digestive tracts. In the lungs, squamous cells make up the lining inside the airways. Squamous cell carcinoma is usually associated with a history of cigarette smoking and most often found near a bronchus (one of the main airways of the lungs), near the central part of the lungs. Squamous cell carcinoma accounts for about 25 percent of all lung cancers.

Large Cell Carcinoma

Large cell carcinoma, also known as undifferentiated carcinoma, comprises about 10 percent of all non-small cell lung cancers, making it relatively rare. Despite its rarity, large cell carcinoma can appear anywhere in the lungs and can grow and spread quickly, all of which makes it harder to treat. Large cell neuroendocrine carcinoma is a fast-growing subtype of large cell carcinoma similar to small cell lung cancer and affects neuroendocrine cells in the lungs.

Other Kinds of Non-Small Cell Lung Cancer

There are other forms of non-small cell lung cancer, but these are much rarer. Adenosquamous carcinoma is a highly uncommon type of non-small cell lung cancer that is a combination of adenocarcinoma and squamous cell carcinoma, though it’s biologically more complex than just a hybrid of the two. 

Sarcomatoid carcinoma is estimated to comprise just 0.3 percent to 3 percent of cases of non-small cell lung cancer. It has been studied as a heterogeneous group of poorly differentiated carcinomas, namely epithelial cells (cells in the lining of the lungs) and sarcomas (cells comprising connective tissue). This form of lung cancer is still not well understood, though the few known cases show that sarcomatoid carcinoma is highly aggressive.

Small Cell Lung Cancer

Small cell lung cancer is rarer than non-small cell lung cancer. Sometimes referred to as oat cell cancer, small cell lung cancer comprises 10 to 15 percent of all lung cancers. Small cell lung cancer appears almost exclusively in current heavy smokers. Despite its rarity, small cell lung cancer grows and spreads faster than non-small cell lung cancer. An estimated 70 percent of people with small cell lung cancer will already have cancer that has spread to other parts of the body during diagnosis. Due to its high rate of spread, small cell lung cancer is generally more receptive to chemotherapy and radiation therapy, but its aggressive nature means that, for most people, the disease may return.

Lung Carcinoid Tumors

Lung carcinoid tumors are a separate type of cancer that starts in neuroendocrine cells, which are cells that have a similar function to nerve cells and hormone-making endocrine cells. Lung carcinoid tumors are relatively uncommon. They thankfully grow slowly and rarely spread to other areas within the body. Lung carcinoid tumors do not have a known connection to smoking. However, atypical lung carcinoids grow faster and are more prone to metastasis, appearing more like a fast-growing tumor.

Signs and Symptoms of Lung Cancer

The symptoms of lung cancer can vary from person to person, type to type. In the early stages of lung cancer there may not present any noticeable symptoms. The most common symptoms of lung cancer include:

  • A sudden, persistent cough
  • Coughing up blood
  • Headaches
  • General fatigue
  • Shortness of breath
  • Wheezing and hoarseness
  • Chest pain
  • Sudden loss of weight

If lung cancer spreads, it can cause a variety of other symptoms. If it spreads to the bones, you may notice bone pain, particularly in your back and hips. Lung cancer that spreads to the brain can cause changes to the nervous system, like dizziness, a loss of balance and coordination, and weakness in the arms and legs. Lung cancer that spreads to the lymph system can result in swelling in the lymph nodes found in the neck and above the collarbone.

Diagnosing Types of Lung Cancer

Diagnosing any type of lung cancer requires an evaluation from a doctor. For those with an increased risk of lung cancer, your healthcare provider may recommend annual screenings involving low-dose CT scans. This mainly comprises those who are age 55 or older and have a history of heavy cigarette smoking but are otherwise healthy.

For those who don’t undergo annual screenings, doctors will perform a variety of tests to diagnose the type of lung cancer you have. Imaging tests, including CT scans and x-rays, can help to reveal abnormal masses and lesions in the lungs. If you have a cough, your doctor may examine your spit and phlegm under a microscope to identify lung cancer cells. Lastly, your doctor may require a biopsy, which involves taking a sample of lung tissue and analyzing them in a lab.

Treatments for Lung Cancer

Treatments for types of lung cancer can vary based on the staging. Surgery is one of the most common types of treatment and involves removing cancerous tissue and potentially some healthy tissue surrounding cancerous tumors. This is often recommended if the cancer is confined to the lungs.

Radiation therapy and chemotherapy are also common forms of lung cancer treatment. These targeted therapies have been found to be particularly effective with faster-growing types of lung cancer. Immunotherapy, which involves using your own immune system to fight cancer, is usually reserved for more advanced forms of cancer.

Lung cancer comes in several different types. The best way to know for sure the type of lung cancer you have is to consult your doctor for a professional diagnosis. If you notice any mysterious symptoms, see your doctor immediately. The sooner you receive a diagnosis, the better the potential outlook.

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January 17, 2020