Lung cancer is one disease, but it comes in different forms.

Some lung cancers involve gene mutations that affect how quickly the cancer grows. The anaplastic lymphoma kinase (ALK) mutation is one of those gene changes.

Knowing whether your cancer is ALK positive can help your doctor figure out which treatments will work best against it and what outlook you may expect.

To learn your ALK status, your doctor will remove a sample of your cancer during a biopsy and test it. They will also look for other gene changes that are linked to lung cancer.

ALK is short for anaplastic lymphoma kinase. It’s a mutation in the DNA of your lung cells that happens when two genes become fused, or stuck together.

When you have this mutation, your lung cells make too many copies of themselves. These cells are cancerous and can spread to other parts of your body.

About 5 percent of people with non-small cell lung cancer (NSCLC) have the ALK-positive kind. It’s most commonly seen in people with the adenocarcinoma type of NSCLC.

About 72,000 people are diagnosed with ALK-positive lung cancer worldwide each year, according to the advocacy group ALK Positive.

ALK-positive lung cancer responds very well to a group of targeted drugs called ALK inhibitors. Chemotherapy and other drugs also work against this cancer.

However it often returns after treatment.

How long a person might live with ALK-positive lung cancer depends in part on its stage at diagnosis. In a 2018 study, people with stage 4 ALK-positive lung cancer lived for an average of nearly 7 years after their diagnosis.

Your type of treatment also matters. People in a 2019 study who took the targeted drug crizotinib (Xalkori) lived longer than those who received chemotherapy.

Your age might also affect your life expectancy, according to 2019 research. Younger people are often diagnosed at a later stage when their cancer is harder to treat. People ages 60 and over sometimes live longer because they’re diagnosed at an earlier stage.

Overall, people with early-stage non-small cell lung cancer are 61 percent as likely as those without cancer to still be alive 5 years later, according to the American Cancer Society. Once the cancer has spread to other organs, five-year survival drops to 6 percent.

Survival rates for ALK-positive lung cancer are slightly better than those for non-small cell lung cancer overall. The aforementioned 2018 study found that people with late-stage ALK-positive disease live for an average of nearly 7 years.

Symptoms might not appear until you’ve had the cancer for some time and it has spread from your lungs to other parts of your body.

The symptoms of ALK-positive lung cancer are the same as those of other types of lung cancer, including:

  • a cough that doesn’t go away
  • chest pain that gets worse when you cough or laugh
  • shortness of breath
  • a hoarse voice
  • wheezing
  • losing weight without trying
  • feeling weak or tired

Having symptoms like these doesn’t mean you have cancer. These types of symptoms are much more likely to be a less serious condition, such as an upper respiratory infection.

But sometimes lung cancer is missed in younger people and nonsmokers because it tends to be more common in older people who smoke. If your doctor can’t find another reason for your symptoms, ask for more tests or get a second opinion.

The ALK mutation isn’t inherited like the BRCA mutations that cause breast cancer. This gene change happens during your lifetime.

ALK-positive lung cancer is most common in women under age 50 who have never smoked, according to ALK Positive.

People with ALK-positive lung cancer have a gene change that affects the way their lung cells grow and divide.

This type of lung cancer used to be hard to treat, but today there are a group of targeted drugs that are very effective against it.

If you’ve tried a few different drugs and the treatment you’re on is no longer keeping your cancer under control, ask your doctor if you can enroll in a clinical trial of a new therapy.