Medical marijuana ‘may be substituting for opioids for cancer-related pain’
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Medical marijuana legalization between 2012 and 2017 appeared associated with a lower rate of opioid prescriptions and pain-related hospitalization among some adults being treated for newly diagnosed cancer, according to a study.
“We know that opioid use is declining among patients with cancer and that marijuana use is increasing among them; this increase is related to the recent wave of medical marijuana legalization,” Yuhua Bao, PhD, associate professor of population health sciences at Weill Cornell Medical College, told Healio. “We do not know if medical marijuana legalization has led to changes in opioid use for patients with cancer and what the implications are for pain management outcomes.”
In the cross-sectional study, published in JAMA Oncology, Bao and colleagues reviewed 2012 to 2017 national commercial claims data and used a difference-in-differences design to evaluate associations of interest for patients living in 34 states without medical marijuana legalization by Jan. 1, 2012. In a secondary analysis, they assessed differences between medical marijuana legalization with vs. without legal allowances for retail dispensaries.
The analysis included 38,189 patients newly diagnosed with breast cancer, 12,816 patients with colorectal cancer and 7,190 with lung cancer. Patients identified for inclusion had private insurance, were aged 18 to 64 years and had received anticancer treatment during the 6 months after a new cancer diagnosis.
Main outcome measures included having 1 or more days of opioids or long-acting opioids, total morphine milligram equivalents of any opioid dispensed to patients with 1 or more opioid days, and one or more pain-related hospital events (ED visits or hospitalizations) during the 6 months after cancer diagnosis.
Results showed an association of medical marijuana legalization with decreases in rates of 1 or more opioid days, from 90.1% to 84.4% (difference, 5.6 percentage points; 95% CI, 2.2-9) among patients with breast cancer, 89.4% to 84.4% (difference, 4.9 percentage points; 95% CI, 0.5-9.4) among patients with colorectal cancer and 33.8% to 27.2% (difference, 6.5 percentage points; 95% CI, 1.2-11.9) among patients with lung cancer.
“Medical marijuana legalization was associated with a 5.5% to 19.2% relative reduction in the rate of receiving at least one opioid prescription,” Bao told Healio. “The magnitude of the reduction varied by the type of cancer and whether the patient received prescription opioids prior to their cancer diagnosis.”
The study also showed an association of medical marijuana legalization with a decrease in the rate of one or more pain-related hospital events, from 19.3% to 13% (difference, 6.3 percentage points; 95% CI, 0.7-12), among patients with lung cancer with recent opioids. Researchers noted a sizable but nonsignificant reduction among patients with breast cancer.
The findings warrant further study about the current use of medical marijuana in relation to decreased opioid prescription, Bao said.
“With increasing medical marijuana legalization, marijuana may be substituting for opioids for cancer-related pain to some extent, with little knowledge about its effectiveness or safety,” she said. “There is an urgent need for research and practice guidelines to support clinical decisions about marijuana use for cancer-related pain.”
For more information :
Yuhua Bao, PhD, can be reached at Weill Cornell Medicine, 425 E. 61st St., New York, NY 10065; email: yub2003@med.cornell.edu.
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