Many Americans diagnosed with cancer continue to drink alcohol regularly — sometimes heavily and sometimes during treatment, a new study shows.

The study, of over 15,000 U.S. cancer survivors, found that 78% were current drinkers. And of them, significant percentages said they binged or engaged in other “risky” drinking. The same patterns were seen even among people undergoing cancer treatment.

Experts said the findings are concerning, in part because alcohol increases the risk of certain cancers. Drinking during cancer treatment, meanwhile, may interfere with the effectiveness of some therapies or boost the chances of side effects.

“There were a lot of risky drinking behaviors in this study, which is surprising,” said senior researcher Yin Cao, an associate professor at Washington University School of Medicine in St. Louis.

It is true, Cao said, that there is still a lot left to learn about how drinking — including problem drinking — affects cancer survivors’ health over the long haul. There’s limited information, for example, on whether drinking after a cancer diagnosis increases the chances of a recurrence.

On the other hand, heavy drinking has well-known health hazards. And there already are “clear guidelines” encouraging everyone — cancer survivor or not — to limit their drinking, for a host of health reasons, Cao said.

Those include guidelines from the American Cancer Society (ACS), which say that alcohol use is one of the most important changeable risk factors for cancer.

The best course is to not drink at all, said Dr. Farhad Islami, senior scientific director of cancer disparity research at the ACS.

“But if you choose to drink,” Islami said, “you should limit your intake to no more than one drink per day for women, and two per day for men.”

Islami, who was not involved in the new study, said it is highlighting a basic fact that many people, including cancer survivors, do not know.

“Most people know that smoking causes cancer,” he said. “But not many people are aware that alcohol use is also a risk factor.”

Drinking has been linked to at least seven cancers, Islami noted. Those include breast, colon and liver cancers, as well as tumors of the mouth, throat, esophagus and larynx.

Islami said that cancer survivors, like everyone else, should limit their drinking, regardless of the type of cancer they had. That’s partly to lower the risk of developing a second cancer that is linked to drinking.

As far as alcohol fueling a recurrence of the original cancer, there is only limited research available. According to the ACS, studies suggest that drinking may shorten the lives of people who survive cancers of the liver, mouth or throat. But there’s not enough information to say whether it raises the risk of recurrence for other cancer types.

For the latest study, published online Aug. 10 in JAMA Network Open, Cao’s team used data from an ongoing federal health study of U.S. adults. Among over 142,000 participants, the researchers found just under 15,300 who reported a cancer diagnosis.

Of that group, 78% said they were drinkers. And among those drinkers, almost one-quarter said they’d gone on a binge in the past year (downing six or more drinks), and 13% regularly exceeded “moderate” drinking (more than two drinks on a typical day).

Meanwhile, 38% reported “hazardous” drinking. That was based on a standard questionnaire that doctors use to screen for problem drinking; it asks people how often they drink, how much they have and how often they binge.

The researchers also found that active cancer treatment did not seem to alter people’s drinking habits: Over 1,800 study participants had undergone cancer treatment in the past year, and their drinking habits during that time were nearly identical to other cancer survivors.

Again, Cao said, it’s not fully clear how drinking impacts cancer treatment. But studies suggest that people with problem drinking fare worse after certain cancer surgeries.

Plus, the ACS says, many cancer drugs are broken down in the liver, and alcohol use could potentially slow down that process, increasing medication side effects.

Islami suggested that people undergoing cancer treatment ask their doctors whether they should avoid alcohol.

That brings up another, broader question: How often do health care providers ask cancer patients about their drinking habits and offer advice?

Cao said it’s unclear. But, she added, one hope is that the new findings will put the issue on the radar of more health care providers.

More information

The American Cancer Society has lifestyle advice for cancer survivors.

SOURCES: Yin Cao, ScD, MPH, associate professor, medicine and surgery, Washington University School of Medicine, St. Louis; Farhad Islami, MD, PhD, senior scientific director, cancer disparity research, American Cancer Society, Atlanta; JAMA Network Open, Aug. 10, 2023, online