15% of U.S. Cancer Patients Are Active Smokers at Time of Diagnosis

Nearly half of patients diagnosed with cancer in 2023 had a history of smoking, and 15% were smokers at the time of their diagnosis, according to new Yale Cancer Center-led research published in in JAMA Oncology.

The study used data from the National Cancer Database (NCDB)—the largest cancer database in the United States—which began incorporating patients’ smoking status in 2023. The database is an important resource for doctors, offering critical insight into which treatments might be the most effective and safest for particular individuals. Tobacco smoking is associated with an increased risk of a wide range of cancers including those of the lung, mouth and throat, esophagus, and liver. Adding smoking as a variable to the database will help doctors learn how smoking might impact outcomes of different cancer treatments.

“This is the broadest look at smoking within the U.S. cancer population available,” says Yale Cancer Center’s Daniel Boffa, MD, the study’s senior investigator.

Smoking is the cause of about one in five cancer diagnoses in the United States. And today, about 12% of the U.S. population are active smokers. For their new study, Boffa and his colleagues wanted to investigate how prevalent smoking was among those who have cancer compared with the general population.

The NCDB collects data on patient demographics, cancer stage, treatments administered, health outcomes, and more. In 2023, participating hospitals began including patients’ smoking status, in part to make sure physicians were asking patients about smoking and to enable researchers to study how smoking changes the safety or effectiveness of treatment. Of the 1.6 million cancer patients entered into the database that year, nearly 97% had information on smoking status.

“Treatments can have different levels of effectiveness based on whether someone has a smoking-related cancer or not,” says Boffa, who is also a professor of surgery (thoracic) at Yale School of Medicine. “So, this information is really important for doctors to know when treating people for certain cancer types.” For example, lung cancers in patients who have never smoked are much more likely to be successfully treated through therapies that target underlying genetic mutations that may be driving the disease instead.

The team found that 47% of patients in the NCDB who were diagnosed with cancer in 2023 were either former or current smokers. “When you compare that to 12% of the U.S. population—that’s a fourfold increase in tobacco smoking in the cancer population compared to the general population,” says Boffa. “This highlights the relationship between tobacco smoking and cancer.”

They also found that 15% of those diagnosed were active smokers. “This is a huge opportunity because getting people to quit smoking after being diagnosed with cancer is a really powerful way to increase survival,” says Boffa. Quitting not only makes treatments easier on patients because it reduces the risk of side effects and complications, but it can also help treatments work better. “Quitting can have a more impressive impact on a person’s outcome than many of the new treatments we have.”

Furthermore, the prevalence of active and former smokers varies across different parts of the country. For example, four states in the southeastern U.S.—Kentucky, Tennessee, Alabama, and Mississippi—had the highest prevalence of active smokers.

The findings highlight that the addition of smoking cessation resources to cancer care programs could be lifesaving for a significant number of patients, and including smoking status in the NCDB could help determine how to prioritize resource distribution.

“If we can bring smoking cessation resources to states where certain groups are more likely to be actively smoking, we could really move the needle and improve cancer care outcomes,” Boffa says.