Department of Research & Evaluation News

It’s well established – but not widely known – that smoking cigarettes increases the risk of bladder cancer. Now, new research shows that current and former smokers are also at higher risk of having their bladder cancer recur after treatment.

The study, published November 30 in JAMA Network Open, analyzed data from the Be-Well Study, a prospective study following 1,472 patients diagnosed with non-invasive bladder cancer between 2015 and 2019 at Kaiser Permanente Northern California and Kaiser Permanente Southern California. Non-invasive bladder cancer is the most common type of bladder cancer.

“Be-Well is one of the largest cohorts of non-muscle invasive bladder cancer patients being followed in the world,” said study co-author Reina Haque, PhD, a senior cancer epidemiologist with the Kaiser Permanente Southern California Department of Research & Evaluation. “Because the risk of cancer recurrence or progression is high in this group of patients, our study set out to identify modifiable risk factors that may help stem that risk.”

Study lead author Marilyn L. Kwan, PhD, a research scientist at the Kaiser Permanente Division of Research, said: “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. 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.”

Of the 1,472 patients studied, 874 were former cigarette smokers, 111 were current cigarette smokers, and 487 had never smoked. The study showed that the number of pack-years of cigarette use, and the number of cigarettes smoked per year, were associated with recurrence risk. The highest recurrence risk — more than twice the risk of nonsmokers — was seen in patients who had smoked for 40 or more years. The study did not see any association between the risk of recurrence and use of pipes, cigars, e-cigarettes, or cannabis.

The researchers also looked at patients’ use of smoking interventions after their bladder cancer diagnosis in a sub-sample. They found that of the 106 patients who were current smokers or who had recently quit smoking, more than half received at least one smoking intervention. These included prescription medications and wellness coaching.

“We have a smoking cessation program that aims to reach patients before their cancer surgery in Kaiser Permanente Northern California,” said Kwan. “Our preliminary findings suggest it would be useful to examine the impact of the smoking cessation program on quit rates and prognosis in bladder cancer patients. To our knowledge, this full evaluation has not been done before.”

The American Cancer Society estimates that in 2022 there will be 81,180 new cases of bladder cancer — 61,700 in men and 19,480 in women. About half of all bladder cancers are non-invasive cancers, 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 urologist with The Permanente Medical Group. “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.”

The study was funded by the National Cancer Institute.

Co-authors include Kelly C. Young-Wolff, PhD, Valerie S. Lee, MHS, Janise M. Roh, MPH, Isaac J. Ergas, PhD, Charles P. Quesenberry, PhD, and Lawrence Kushi, ScD, of the Division of Research; Reina Haque, PhD, and Kimberly L. Cannavale, MPH, of the Kaiser Permanente Southern California Department of Research and Evaluation; Zinian Wang, MS, Christine B. Ambrosone, PhD, and Li Tang, PhD, of the Roswell Park Comprehensive Cancer Center; and Ronald K. Loo, MD, of the Southern California Permanente Medical Group (SCPMG).