A new study from the American Medical Association has found cancer patients with access to legal medical marijuana used fewer opioids. That’s considered a major benefit by cannabis proponents because of the addictive nature of opioids.

The study associated access to medical marijuana with reduced use of opioids in states where legal medical cannabis became available between 2012 and 2017. The AMA based its findings on review of insurance claims and dispensary purchases involving 58,195 people recently diagnosed with cancer.

The researchers, who published their findings in the Journal of the American Medical Association, wrote that “medical marijuana could be serving as a substitute for opioid therapies among some adult patients receiving cancer treatment.”

Patients From 34 States Included in the Study

The study involved patients from 34 U.S. states. Researchers who worked on the study came from the Weill Medical College of Cornell University, Harvard University, the University of Texas and Albert Einstein College of Medicine. It included 38,189 breast cancer patients, 12,816 colorectal cancer patients, and 7,190 lung cancer patients.

The researchers said the need for the study is driven by the “rapid declines” in opioids dispensed to cancer patients in the past decade. They wanted to determine if the expansion of legal medical marijuana around that same time – it’s legal now in 39 states and the District of Columbia – influenced the reduction in opioid use.

The focus on opioid use stems from what the Centers for Disease Control and Prevention calls a national crisis. Federal statistics show the number of prescription opioid-related overdose deaths increased from 3,442 in 1999 to 16,416 in 2020.

Differences in Opioid Use Among Those With Different Types of Cancer

The study looked at the impact of medical marijuana on opioid use in the first six months after someone received a cancer diagnosis. A secondary analysis included with the study looked at differences in opioid use in areas with or without laws allowing retail dispensaries.

Among those diagnosed with breast cancer, there was a 5.6 percent reduction in opioid use, and a 4.9 percent reduction for those with colorectal cancer. For those with lung cancer, the reduction reached 6.5 percent.

Researchers also found an association between medical marijuana legalization and a 6.3 percent reduction in the number of pain-related hospital events for those with lung cancer.

The researchers concluded that medical marijuana “was associated with a lower rate of opioid dispensing and pain-related hospital events among some adults receiving treatment for newly diagnosed cancer. The nature of these associations and their implications for patient safety and quality of life need to be further investigated.”

Previous studies have also researched the use of cannabis with cancer patients. For example, a University of South Carolina study using lab rats found that chemicals in cannabis helped prevent development of colon cancer. Even officials in Texas, where medical marijuana use is heavily restricted, saw enough evidence to approve the use of cannabis by cancer patients.