It’s been known for some time that smoking cigarettes increases the risk of bladder cancer. But now Kaiser Permanente researchers have learned that current and former smokers also have a higher risk of having their bladder cancer come back after treatment has ended.

The new study, published in JAMA Network Open, included 1,472 Kaiser Permanente patients with non-muscle invasive bladder cancer enrolled in the Be-Well Study. The study, which was started in 2015 by a team of investigators from Kaiser Permanente Northern California and Kaiser Permanente Southern California, is one of the largest studies of non-muscle invasive bladder cancer patients in the world. Non-muscle invasive bladder cancer is the most common type of bladder cancer.

Of the 1,472 patients, 874 were former cigarette smokers, 111 were current smokers, and 487 had never smoked. The study showed that the more years and the more cigarettes per day a person smoked, the greater their risk of having their bladder cancer come back after treatment. The highest risk of recurrence was seen in patients who had smoked 40 or more years. These patients had more than twice the risk of having their cancer come back than the nonsmokers. The study did not see any association between the risk of recurrence and use of pipes, cigars, e-cigarettes, or cannabis.

Kaiser Permanente has tobacco cessation programs

“It was important for us to study this group, because bladder cancer patients have not been studied as much as patients with certain other types of cancer,” said lead author Marilyn L. Kwan, PhD, a research scientist at the Kaiser Permanente Division of Research. “Our study not only supports previous smaller studies but expands our understanding of the role tobacco plays in bladder cancer. We want people to know that a long-term history of smoking is associated with a worse prognosis.”

The Northern California Region has a smoking cessation program that aims to reach patients before their cancer surgery. The researchers found that of the 106 bladder cancer patients in the study who were being treated at Kaiser Permanente in Northern California and who currently smoked or who had recently quit smoking, more than half received at least one smoking intervention. These included prescription medications and wellness coaching.

The findings from this research will help us counsel our patients, especially those who are active smokers, on the options available to stop smoking.” – Dr. David Aaronson

“We have a smoking cessation program that aims to reach patients before their cancer surgery,” said Kwan. “These early findings suggest it would be useful to study the impact this program has on quit rates and prognosis in bladder cancer patients.”

The American Cancer Society estimates that in 2022 there were 81,180 new cases of bladder cancer — 61,700 in men and 19,480 in women. About half of all bladder cancers are non-muscle invasive, meaning they are confined to the inner layer of the bladder wall.

“The findings from this research will help us counsel our patients, especially those who are active smokers, on the options available to stop smoking,” said study co-author David Aaronson, MD, a Kaiser Permanente urologist in Oakland. “Smoking has many negative consequences and when people learn it is also associated with bladder cancer they are taken aback — so it’s a great opportunity to get them to quit.”

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