Last month, three states – Virginia, South Dakota and Connecticut – joined the ranks of more than a dozen others that have legalized marijuana – also known as cannabis – for recreational use. Yet, despite these changing laws and growing social acceptance of the drug, a new study finds that use is still lower among cancer patients.

The study, published today in the journal Cancer by researchers at Virginia Commonwealth University Massey Cancer Center, analyzed data from nearly 20,000 people over a span of four years and found that reports of marijuana use peaked at 9% for cancer patients, compared to 14% among people with no cancer history.

“Even when we looked at whether someone used cannabis over the four years of observation and we control for things like age and race, cancer patients are still not increasing their use over time like the general population,” said study lead author Bernard Fuemmeler, PhD, MPH, associate director for population science and interim co-leader of the Cancer Prevention and Control research program at VCU Massey Cancer Center. “I would have expected them to have at least mirrored what was happening in the general population.”

This paper drew on data collected between 2013 and 2018 from the Population Assessment of Tobacco and Health (PATH), which tracks a representative sample of Americans to survey smoking behaviors, including both tobacco and marijuana.

For people who never had cancer, rates of marijuana use rose during the four-year PATH study period. This same period saw a wave of recreational marijuana legalization sweep across the nation.

“Because of law enforcement changing, we expect to see changes in attitudes and perceived benefits and harms,” said study co-author Sunny Jung Kim, PhD, Harrison Scholar at VCU Massey Cancer Center and assistant professor of health behavior and policy at the VCU School of Medicine. “This work gives us perspective on prevalence of cannabis use among cancer patients and how it has changed over time.”

But why aren’t cancer patients following the same trend as the rest of the population? The odds of a cancer patient using marijuana in the past year were essentially flat between 2013 and 2018.

“There is that element of a life-changing moment when you have cancer,” said Fuemmeler, who is also a professor of health behavior and policy in the VCU School of Medicine and holds the Gordon D. Ginder, MD Chair in Cancer Research at Massey. “You have to be mindful of your health and contemplate whether something like cannabis is helpful or hurtful.”

Regardless of cancer history, this latest analysis revealed that people who reported higher levels of pain were more likely to use marijuana, whereas lower rates of marijuana use were seen among women, older people and those with higher incomes, medical insurance or better mental health.

The authors note the need for greater research into the health effects of marijuana use for cancer patients and survivors so that doctors and patients can have more informed conversations about whether the potential benefits might outweigh the risks.

“As with all health decisions, it’s best to talk to your doctor before making any big changes,” said study co-author Egidio Del Fabbro, MD, the Thomas Palliative Care Endowed Chair and director of palliative care at VCU Massey Cancer Center and professor of internal medicine at VCU. “Now that marijuana is becoming legal in more parts of the country, we’re expecting more questions, and although we may not have all the answers, we’re here to listen and provide our patients with the best available evidence.”

Additional authors on the study include Elizabeth Do, Ph.D., and Albert Ksinan, PhD, both of the VCU Department of Health Behavior & Policy.

This research was funded by Massey’s NCI Cancer Center Support Grant P30 CA016059.