Despite California’s success in reducing tobacco use, a new study published in JAMA Network Open demonstrates the continued and significant burden tobacco inflicts on people with cancer.

The study was conducted by researchers at UC Davis Comprehensive Cancer Center who used data collected from the California Cancer Registry, a state-mandated population-based cancer surveillance system managed by UC Davis. The study looked at people diagnosed with one of 12 tobacco-related cancers from 2014 to 2019 in California. The analyses showed that nearly half of the cancer deaths over two years, between 2017 and 2019 (totaling 93,764 Californians), were associated with tobacco use.

Frances Maguire

“This is almost double what was previously estimated in a study that looked at 2014 data,” said Frances Maguire, a California Cancer Registry researcher who is the lead author of the study. “However, we believe this is a more accurate representation since tobacco use data came directly from individual patients with cancer rather than estimates based on general population surveys. This study is also specific to the 12 tobacco-related cancers.”

Tobacco status data used in the study included use of cigarettes, other smoked tobacco products (such as cigars and pipes) and smokeless tobacco products (such as chewing tobacco and snuff). Data on the use of vaping products is not yet collected by the registry.

The study results showed that among the nearly 400,000 patients diagnosed with a tobacco-related cancer from 2014 to 2019, most (72.3%) were over 60 years old. The majority (57.7%) were non-Hispanic white, were men (58%) and nearly half (46.6%) had lung or colorectal cancers.

Cancers most related to tobacco use

The greatest number of deaths attributable to tobacco consumption, for both men and women, were from cancers of the lung and bladder. The greatest proportions of tobacco-related cancer leading to deaths were found in the:

  • lung (90.2%)
  • larynx (85.6%)
  • esophagus (58%)
  • oral cavity/pharynx (55.5%)
  • bladder (52.7%)

Men mostly had higher proportions of tobacco-related cancers compared with women, with the largest differences seen in:

  • liver cancer (33.9% men, 11.1% women)
  • stomach cancer (25.9% men, 6.5% women)
  • kidney cancer (23.8% men, 6.8% women)
  • acute myeloid leukemia (20.8% men, 3.0% women)
  • bladder (52.7%)
Theresa Keegan

UC Davis researcher Theresa Keegan, the study’s co-author and co-principal investigator with the California Cancer Registry, said, “Smoking remains the largest preventable cause of death from cancer and other diseases. This study shows that tobacco continues to kill Californians with cancer at an alarming rate. Cancer registries can play an important role in monitoring progress for this priority population.”

Tobacco use trends

“What is important to note in the study findings is the number of Californians diagnosed with these 12 types of cancers who still use tobacco: about 1 in 5 men (19.6%) and 1 in 7 women (14.5%). Some people with lung cancer or laryngeal cancer had even higher use rates at 30—37%,” said senior author Elisa Tong, a UC Davis Health internist and cancer center tobacco researcher. “It’s important to remember that it’s never too late to quit smoking even after a cancer diagnosis, because quitting can improve cancer treatment outcomes and significantly reduce mortality.”

Other authors of the study included cancer center affiliates Ani S. Movsisyan, Cyllene R. Morris, and Arti Parikh-Patel.