Treatments linked to drop in lung cancer deaths

The study shows how improvements in treatment have helped lower deaths from lung cancer. Lordn / iStock / Getty Images Plus

Lung cancer is the leading cause of cancer death in the U.S. for both men and women. But the number of cases—the incidence—has been falling slowly but steadily, beginning around the turn of the century. This drop is largely due to fewer people smoking tobacco, the leading cause of lung cancer.

Correspondingly, the number of deaths from lung cancer (the mortality rate) has also been dropping. But the drop in smoking is likely not the only cause of this decline. Beginning in 2003, many new drugs have been approved for the treatment of the most common type of lung cancer, called non-small cell lung cancer (NSCLC). These drugs target cancer cells that depend on specific genetic changes.

While such targeted therapies don’t cure lung cancer, they can increase the life expectancy of people whose cancers have the specific alterations. Doctors began routinely testing people with NSCLC in 2013 for the alterations targeted by these newly approved drugs. How the widespread adoption of these drugs has affected lung cancer mortality, however, hasn’t been well studied.

To look more closely, researchers from NIH’s National Cancer Institute (NCI) led by Dr. Nadia Howlader compared information from a cancer incidence database with mortality data from death certificates. They examined the incidence of NSCLC and small-cell lung cancer (SCLC), the other main type of lung cancer, between 2001 and 2016. They then identified deaths from these NSCLC and SCLC cases from 2006-2016. No similar advances in treatment for SCLC were made during those years. Results were published on August 13, 2020, in the New England Journal of Medicine.

The team found that while the incidence of NSCLC decreased during 2001-2016, mortality dropped even more. For men, the incidence decreased by about 2% every year from 2001 to 2008, and by about 3% from 2008-2016. Mortality dropped by about 3% per year up to 2013, and then by more than 6% per year after 2013.

The incidence of SCLC also declined for both men and women, even faster than the incidence of NSCLC. However, the researchers didn’t see any additional drops in mortality from SCLC beyond those caused by these decreases in incidence. This was likely due to the lack of improvements in treatment for SCLC.

The study couldn’t directly show that the new drugs caused the additional declines in mortality for NSCLC. However, no other major changes in treatment occurred during this period. Using CT imaging to screen current and former smokers for lung cancer has been shown to save lives, but such screening has not yet been widely adopted.

“The survival benefit for patients with non-small cell lung cancer treated with targeted therapies has been demonstrated in clinical trials, but this study highlights the impact of these treatments at the population level,” Howlader says.

In 2015, immunotherapy drugs began to be approved for the treatment of NSCLC. In 2018, approvals began for SCLC. These treatments encourage the body’s immune cells to attack cancer cells. Whether such drugs will impact future trends in lung cancer mortality will need to be examined in future studies.