Small-cell lung cancer makes up approximately 15 percent of lung cancers in the United States. The strongest risk factor for this cancer is smoking tobacco.

Small-cell lung cancer tends to be very aggressive and quickly spreads to other parts of the body. In a 2021 study, researchers found that by the time of diagnosis, the cancer spread from the lungs to the brain in about 10 to 20 percent of cases. During treatment, researchers found the cancer spread to the brain in about 50 to 80 percent of cases.

Many people with small-cell lung cancer go into remission during their initial treatment. For the majority of people, small-cell lung cancer relapses within a year. The 5-year relative survival remains at 7 percent.

Remission means signs and symptoms of your cancer have improved. If you achieve complete remission, all signs and symptoms of the cancer are gone.

Read on to learn more about how long remission typically lasts and what factors influence remission length.

Small-cell lung cancer tends to respond well to initial therapy. About 80 percent of cases achieve remission. However, remission lasts less than a year in most cases. Few cases are cured.

Some doctors consider your cancer cured if your remission last more than 5 years.

In a 2020 study, researchers found that more than 90 percent of cases of small-cell lung cancer came back within 2 years.

Permanent remission is possible

Despite having a poor outlook, some people do achieve permanent remission.

In a 2020 case study, researchers presented a 71-year-old woman who achieved complete remission after palliative chemotherapy and radiation as well as surgery to treat cancer that spread from her lungs to her brain. She was still cancer-free at a follow-up 9 years later.

When cancer has already spread beyond the lungs

More than 70 percent of people with small-cell lung cancer have cancer that has spread beyond their lungs when they receive their diagnosis.

Platinum-based chemotherapy is the first-line treatment for these cases. Relapse is classified based on when the cancer comes back:

  • Platinum-resistant: cancer returns during treatment
  • Platinum-refractory: cancer returns within 90 days of treatment
  • Platinum-sensitive: cancer returns 90 days or more after treatment
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Factors that decrease the rate of survival in people with small-cell lung cancer include:

  • loss of body weight (more than 10 percent)
  • low sodium levels (hyponatremia)
  • poor ability to carry out daily activities
  • cancer reoccurrence

The strongest predictor for survival outcomes in people with relapsed small-cell lung cancer is the duration of remission.

Small-cell lung cancer is referred to as “relapsed” if it comes back during treatment. It’s known as “recurrent” if it comes back during maintenance therapy following initial treatment.

Once small-cell lung cancer relapses, it has a very poor outlook. According to 2016 research, half of people who don’t get further treatment live less than 2 to 3 months. People who do get further treatment rarely live more than 6 months.

A 2018 review suggests the median progression-free survival rate for second-line therapy is about 4.6 months. This means half of people live 4.6 months without the cancer progressing. About 51 percent of cancer cases respond to treatment.

The median progression-free survival for people receiving third-line therapy is about 2 months. About 18 percent of cancer cases respond to treatment, according to the review.

Here are answers to some common questions people have about small-cell lung cancer.

Does small-cell lung cancer always come back?

The majority of small-cell lung cancer cases relapse, or come back. However, some people do experience permanent remission. The 5-year relative survival rate is 7 percent.

Can small-cell lung cancer be cured?

Some doctors consider small-cell lung cancer cured if it goes into complete remission for at least 5 years. If the cancer is limited to the lungs, it’s considered curable in about 20 to 25 percent of people.

Cancer that has spread beyond the lungs isn’t considered curable. The American Cancer Society lists the relative 5-year survival rate as 3 percent for small-cell lung cancer that has spread to distant parts of the body.

Can certain treatments prolong remission?

Small-cell lung cancer spreads to the brain in as many as 50 to 80 percent of cases. Brain radiation therapy may help destroy cancer cells in the brain that are too small to be detected.

Brain radiation therapy has been found to decrease the risk of small-cell lung cancer spreading to the brain, but it’s not clear whether it improves overall survival.

How long can you survive small-cell lung cancer?

Research has found that about half of people with cancer localized to the lung live less than 21.8 months. Half of people with cancer that spread beyond the lung live less than 8.9 months. Some people who go into remission live full lives.

Where does small-cell lung cancer spread?

The most common places small-cell lung cancer spreads to are:

  • lymph nodes
  • brain
  • liver
  • adrenal glands
  • bone
  • bone marrow

Small-cell lung cancer is an aggressive form of cancer. It often spreads to other tissues and comes back in most people. Relapse usually occurs within the first couple of years after treatment.

Some people with small-cell lung cancer do go into remission without relapsing. Cancer that’s limited to the lung is sometimes considered curable.

Living with a small-cell lung cancer diagnosis can be difficult, but your doctor and healthcare team can help you figure out the best treatment options. They can also let you know whether there are any clinical trials you may be eligible for.