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A lung cancer diagnosis can be confusing. Here’s what you need to know about the most common types—and subtypes—of lung cancer.

What are the different types of lung cancer?

Lung cancer is generally divided into two categories: non-small cell and small cell lung cancer. (There are other types of cancer that can start in the lungs as well, including carcinoid tumors and asbestos-related mesothelioma.)

Non-small cell is by far the most common, making up 85 percent of all lung cancers. It can be located in the mid-chest, but is also found in other parts of the lung. Non-small cell lung cancer is further divided into subcategories including adenocarcinomas (which make up about 70 percent of non-small cell cancers).

Small cell is typically more centrally located in the lungs. “We often see masses in the mid-chest,” says Nicholas Rohs, M.D., an attending physician at Mount Sinai Health System, in New York.

What are the lung cancer risk factors?

When it comes to non-small cell, the majority of people diagnosed are smokers, but 15 to 20 percent are not. According to Gregory Kalemkerian, M.D., a clinical professor of medicine at the University of Michigan, we don’t know why nonsmokers develop lung cancer. Radon and asbestos exposure are causes, but they’re not very common. Genetic predisposition is still being studied, but Kalemkerian notes it’s rare that it runs in families.

In small cell lung cancer, 98 percent of patients are former or current heavy smokers. The more “pack years” you smoke (defined as the number of packs smoked per day per year), the greater the risk of small cell, says Rohs.

What are the symptoms of lung cancer?

The symptoms are similar for both non-small cell and small cell cancer: coughing, shortness of breath, fatigue, weight loss, lack of appetite and, rarely, severe chest pain and coughing up blood, says Rohs.

The symptoms can be hard to spot in the early stages. Rohs estimates that about 60 percent of people with non-small cell and 75 percent of people with small cell have an advanced form of cancer when it is diagnosed. “Even if you have something growing in your lungs, it may not cause symptoms for a while,” he says. In addition, symptoms can masquerade as other problems, such as allergies, a virus or bronchitis. In some cases, symptoms may be attributed to chronic obstructive pulmonary disease, including emphysema and chronic bronchitis.

What is the treatment for non-small cell lung cancer?

Non-small cell lung cancer is less aggressive than small cell, but any type of lung cancer is still “an aggressive cancer that tends to spread and metastasize,” says Kalemkerian. That’s one reason only about 25 percent of patients come in with early stage (stage 1 or 2).

When a patient has early stage cancer, surgery to remove the cancer is an option. In later stages of non-small cell cancer, where it has spread to lymph nodes in the chest, treatment is commonly chemotherapy and radiation, according to Kalemkerian.

In people with adenocarcinomas (the most common type of non-small lung cancer), the tumor may be tested to determine if there are specific mutations in the DNA. If so, the tumor may better respond to certain targeted oral medications, says Rohs.

If the tumor doesn’t contain these specific mutations, a patient may be a candidate for immunotherapy, another targeted therapy that has been shown to offer a better outcome than chemo.

What is the treatment for small cell lung cancer?

The treatment depends on the type and stage of cancer at diagnosis. In general, the pace of treatment is faster for small cell cancer. These tumors tend to spread more rapidly from the lungs to lymph nodes and other organs in the body. “I’ve seen small cell double in size in two weeks,” says Kalemkerian, adding that chemo and radiation can put about one-quarter of treated people into remission. Doctors may also preventively treat the brain with radiation, as cancer cells that have metastasized (spread in the body) may end up here, he notes.

Expert recommendations for lung cancer patients:

Get a second opinion and see a specialist: “Just in the last year there have been more than half a dozen new drugs approved. The average doctor may not be up to date on this. I suggest everyone get a second opinion at a major academic medical center before they start therapy,” says David P. Carbone, M.D., Ph.D., director of the James Thoracic Center at Ohio State University.

See a palliative care specialist: Palliative care addresses any medical issues that are not related to the cancer itself—for example, pain and quality of life. “Early palliative care actually improves quality and quantity of life,” says Rohs.

Seek out more info: Carbone recommends the LUNGevity Foundation and the Bonnie J. Addario Lung Cancer Foundation as good resources for patients and families.

As previously posted on Health.com