The legalization of medical marijuana use may reduce opioid use in cancer patients.
As of 2022, medical marijuana for pain relief is legal in 37 states and Washington, D.C. Living in these states is associated with a lower rate of opioid dispensing in patients receiving cancer treatments, a paper published Thursday in the journal JAMA Oncology says.
Results of the study show that medical marijuana legalization was associated with a 5.5 percent to 19.2 percent relative reduction in the rate of opioid dispensing (i.e., the rate of receiving at least one opioid prescription) to adult patients aged 18 to 64 who were newly diagnosed with breast, colorectal or lung cancer and receiving cancer treatment.
The analysis involved 38,189 patients newly diagnosed with breast cancer, 12,816 with colorectal cancer and 7,190 with lung cancer. These three cancer types were chosen for the study because of the large number of new cases among those younger than 65.
Between 2012 and 2017, medical marijuana legalization took effect in 14 states: Arkansas, Connecticut, Florida, Illinois, Louisiana, Maryland, Massachusetts, Minnesota, New Hampshire, New York, North Dakota, Ohio, Pennsylvania and West Virginia.
Opioids, which are potent synthetic painkillers, are frequently used to treat all kinds of pain, including the type afflicting cancer patients. Opioids are also highly addictive, and their use in medicine has been linked to an increased self-administration of the drugs over several decades.
Over 70,000 people died from drug overdoses in the U.S. in 2019, and 48,000 of these fatalities were attributed to non-methadone synthetic opioids, a category that includes fentanyl.
Yuhua Bao, lead author of the paper and a health economist at Weill Cornell Medicine, told Newsweek, "The magnitude of the reduction [of opioid dispensing in cancer patients] varied by the type of cancer and whether the patient received prescription opioids prior to their cancer diagnosis.
"Our findings suggest that with increasing medical marijuana legalization, marijuana may be substituting for opioids for cancer-related pain to some extent," she said.
There is some evidence that medical marijuana can provide pain relief for cancer patients, as well as management of nausea and nerve damage.
Cannabis contains compounds called cannabinoids, which are the active ingredients in both medicinal cannabis and recreational marijuana. However, more studies need to be done in this area to strengthen the evidence of a link between marijuana and pain relief.
Medicinal cannabis use also has side effects, ranging from nausea and weakness to psychosis. However, a paper published earlier this year in the journal Frontiers in Pain Research said that "the adverse effects from cannabinoids for cancer treatment are generally well tolerated by the patients and categorized as mild to moderate."
The reason for the reduction in opioid dispensing in the study is not known.
Bao said, "The pharmacy claims data we used do not shed light on the reason for the reduced dispensing. A combination of factors may have contributed to the reduction, including reduced patient requests for/fills of opioids and reduced clinician prescribing of opioids.
"These behaviors could be driven by actual substitution of medical marijuana for opioids or perceived substitutability," she said.
Legal access to medical marijuana may have led oncologists and other practitioners to prescribe fewer opioids, or perhaps they were asked for less by patients who were self-managing their pain with marijuana.
"Without data on clinician practices or patient use of medical marijuana, the nature of the observed associations remains uncertain," the authors wrote in the paper.
Additionally, Bao said this study does not represent the final word on marijuana versus opioids in terms of pain relief for cancer patients.
"We know little about the effectiveness or safety associated with marijuana use in place of or in addition to opioids, especially given that many patients may be using marijuana without a clinician's guidance or monitoring," she said.
"Our study thus points out the urgent need for research and practice guidelines to support clinical decisions about marijuana use for cancer-related pain," Bao said.
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