Lung cancer is the second most common cancer and the leading cause of cancer-related death worldwide.

There are two main types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). These types differ in their prevalence, treatment, and outlook.

This article outlines the prevalence of NSCLC compared with other lung cancers as well as over time. It also lists the risk factors associated with NSCLC and provides statistics on survival rates for the condition.

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There are two main types of lung cancer: SCLC and NSCLC. Together, these cancers account for more than 95% of all lung cancers. On its own, NSCLC accounts for up to 85% of all lung cancers in the United States.

There are three main subtypes of NSCLC:

  • Adenocarcinoma: This is the most common type of primary lung cancer, accounting for around 40% of all lung cancer cases. It is the leading cause of cancer death in the U.S., and it is the most common lung cancer among people who have never smoked.
  • Squamous cell carcinoma (SCC): This is the second most common type of NSCLC, accounting for about 30% of all NSCLC cases. This subtype is associated with smoking, and it is more common among women.
  • Large cell carcinoma (LCC): This type accounts for approximately 5–10% of all lung cancer cases. This subtype can appear on any part of the lung, and it tends to grow and spread rapidly.

Below are some of the risk factors associated with NSCLC.

Age

Although the average age at NSCLC diagnosis is 70 years old, one 2015 study suggests that some cases appear in people younger than 40 years of age.

Some factors associated with NSCLC cases in younger people include:

  • being a woman
  • being Asian or being a Pacific Islander
  • having adenocarcinoma

Gender

Compared with men, women appear to have an increased risk of NSCLC complications. According to a 2021 review, this may be due to the overexpression of the hormone receptor estrogen-related receptor alpha, which is receptive to the hormone estrogen.

Race

Black men have a 15% higher risk of developing lung cancer than white men, while Black women are 14% less likely to develop lung cancer than white women.

A 2019 study found that Black people with NSCLC had more mutational changes in their DNA than people of other ethnicities. However, one 2020 study states there is no difference in NSCLC treatment and survival when Black people and white people receive equal access to treatment.

Smoking

According to the Centers for Disease Control and Prevention (CDC), people who smoke are 15–30 times more likely to develop lung cancer and die from such cancers than people who have never smoked.

The CDC also notes that around 80–90% of deaths from lung cancer are attributable to smoking. This risk increases in line with the number of years a person smokes for and the number of cigarettes they smoke each day.

Exposure to secondhand smoke

Most people who do not smoke who develop lung cancer develop NSCLC as opposed to SCLC. The most common NSCLC subtype among people who do not smoke is adenocarcinoma.

A 2017 Korean study of people with NSCLC found that roughly 38% of NSCLC cases occurred in people who had never smoked.

Exposure to secondhand smoke accounts for around 15–35% of lung cancer cases among people who have never smoked.

Exposure to toxic substances

Exposure to the following substances increases the risk of lung cancer:

Radon exposure is the leading cause of lung cancer among people who do not smoke. However, exposure is associated with an increased risk of SCLC rather than NSCLC.

The 5-year survival rate refers to the percentage of people who live 5 years or more following their initial cancer diagnosis. According to American Cancer Society (ACS) survival statistics, NSCLC has a 5-year survival rate of 25%, while SCLC has a 5-year survival rate of 7%.

Five-year survival rates vary according to lung cancer stage, which is the extent to which the cancer has spread. The three stages and their associated survival rates are as follows:

  • Localized disease: This is cancer that has not spread outside the lungs. The 5-year survival rate for NSCLC at this stage is 63%.
  • Regional disease: This is cancer that has spread to nearby areas outside the lung. The 5-year survival rate for NSCLC at this stage is 35%.
  • Distant disease: This is cancer that has spread to distant areas. The 5-year survival rate for NSCLC at this stage is 7%.

According to a 2020 review, the following factors have significantly improved treatment outcomes and survival rates among people with NSCLC:

  • earlier diagnosis
  • a more accurate and detailed classification system for lung cancers
  • advances in treatment

A 2015 meta-analysis notes that the discovery of epidermal growth factor (EGF) mutations and the effectiveness of EGF inhibitors have further improved lung cancer survival rates, especially among people with advanced disease.

At the time of this article’s publication, there is a decline in cases of SCC and a continuous rise in cases of adenocarcinoma.

The decline in SCC is likely due to increases in the number of people who are giving up smoking or choosing never to begin smoking. The cause of the rise in adenocarcinoma is currently under investigation.

One 2020 study found an increase in lung cancer incidence among young women, which was driven by increasing rates of adenocarcinoma.

A possible reason for this could be that women started smoking when manufacturers introduced filtered cigarettes in the 1960s. According to the researchers, filtered cigarettes cause tobacco smoke to distribute throughout the lungs in a way that increases the risk of adenocarcinoma.

The ACS predicts that approximately 235,760 people in the U.S. will receive a diagnosis of lung cancer in 2021.

Generally, lung cancer incidence and mortality rates are slowly declining. However, the pace of decline is faster among men than among women, and it started at least a decade earlier for men than women.

Some research suggests that women may be less likely to quit smoking than men, and this may account for the gender differences in lung cancer rates.

Quitting smoking plays an important role in lung cancer outlook. A 2020 study suggests that quitting smoking at any time can reduce a person’s risk of dying from lung cancer.

The greater the elapsed time between quitting smoking and lung cancer diagnosis, the greater the odds of survival, as outlined below:

  • Quitting less than 2 years before diagnosis: This is associated with a 12% reduced risk of mortality.
  • Quitting 2–5 years before diagnosis: This is associated with a 17% reduced risk of mortality.
  • Quitting more than 5 years before diagnosis: This is associated with a 20% reduced risk of mortality.

NSCLC is the most common type of lung cancer. It has three subtypes: adenocarcinoma, SCC, and LCC.

The incidence of NSCLC has changed over time. Subtypes associated with smoking are declining, as increasing numbers of people are giving up smoking or choosing never to smoke in the first place. However, subtypes not related to smoking are on the rise, and experts are currently unsure about why this is the case.

Survival rates for NSCLC are improving, thanks to earlier diagnoses, more accurate and detailed disease classification, and advances in lung cancer treatment.