FRIDAY, Jan. 24, 2020 (HealthDay News) -- An immune system that's not functioning normally may lead to lung cancer in patients who don't smoke, a new study suggests.

"A strong immune system helps to keep inflammation under control and chronic inflammation is known to promote cancer," said co-author Rayjean Hung.

"Our research suggests that it's underlying dysfunction of immune regulation that can lead to lung cancer, as if a shield is down," she said. Hung is a senior investigator at Sinai Health's Lunenfeld-Tanenbaum Research Institute in Toronto.

For the study, Hung's team looked at the genes of 80,000 people to see if conditions other than those that compromise lung function -- such as chronic obstructive pulmonary disease (COPD) -- can cause lung cancer. As many as 70% of lung cancer patients also have existing COPD or airflow obstruction.

"Who suffers from lung cancer goes beyond what could be explained by smoking," Hung said. "Our findings provide more insight on why lung cancer occurs in nonsmokers and points to the importance of immune regulation."

Screening CT scans can find lung cancer before symptoms appear. Finding the disease early can make curing it more likely. These findings expand the number of people who should be screened, the researchers said.

The report was published online recently in the journal Nature Communications.

More information

For more on lung cancer, head to the American Cancer Society.