Many women use cannabis to help manage gynecologic pain conditions.
When patients ask or tell clinicians about this treatment approach, however, few if any controlled trials exist to inform medical guidance.
A recent review of studies in this area presents a “thorough analysis of this very relevant topic,” said Erin A. Blake, MD, of Presbyterian Cancer Care, Rio Rancho, N.M..
The findings “are consistent with my anecdotal clinical findings as well as the results of my own research,” Dr. Blake said. “Cannabis products represent an underutilized but likely effective modality to relieve pain and other symptoms experienced by our patients.”
Mostly in the dark
Cannabis products “are unregulated and the data we have surrounding them is extremely limited due to outdated federal laws,” said Dr. Blake, who in 2019 described nonprescription cannabis use for symptom management by women with gynecologic malignancies. “Our ability to practice evidence-based medicine related to cannabis products will be limited until we are legally and financially able to design trials to evaluate them in a controlled fashion.”
For the new review, Jenell S. Coleman, MD, MPH, with Johns Hopkins University, Baltimore, and colleagues, identified 16 studies since 1990, including Dr. Blake’s, that examined the use of cannabinoids for managing pain from gynecologic conditions.
Dr. Jenell S. Coleman
Dr. Coleman and her coauthors, Angela L. Liang and Erin L. Gingher, analyzed eight cross-sectional studies, six prospective studies, and two randomized controlled trials.
Patients who used cannabis tended to do so “multiple times per week, and they used a variety of delivery methods and a wide range of doses,” the authors said. “One of the most common reasons for cannabis use was pain management, and all the cross-sectional studies found that most women reported pain relief with cannabis use, especially among women who used a combination of CBD plus THC compared with either cannabinoid alone.”
Cross-sectional studies included patients with chronic pelvic pain (in two of the studies), vulvodynia (one), endometriosis (four), and gynecologic malignancy (two). These studies included between 36 and 3,426 participants and were conducted in the United States, Canada, Australia, and New Zealand.
In one Australian study, for example, Armour and colleagues asked 484 patients with endometriosis to rate the effectiveness of self-management strategies, including cannabis, heat, diet, and exercise, for reducing pelvic pain. Cannabis was used by 13% of the participants and had the highest average effectiveness rating: 7.6 on a 10-point scale.
In some cases, patients who use cannabis may decrease their use of other pain medications, the review found.
Cannabis side effects may include dry mouth, sleepiness, increased appetite, palpitations, and a “high” associated with THC.
Enhancing endogenous cannabinoids
The six prospective cohort studies and two randomized controlled trials examined the effectiveness of compounds – including palmitoylethanolamide (PEA) and a fatty acid amide hydrolase inhibitor – that can enhance endogenous cannabinoids.
Studies of PEA combined with antioxidants showed that these treatments significantly decreased pain from primary dysmenorrhea, pelvic pain, and interstitial cystitis. PEA-combination medications were well tolerated, with nausea and spotting as potential side effects.
On the other hand, a study that assessed a fatty acid amide hydrolase inhibitor found that it did not decrease pain from interstitial cystitis.
Dr. Coleman began reviewing the endocannabinoid system and cannabis research after hearing from patients who were using cannabis for pelvic pain.
Seeing various preclinical data that suggest cannabis could be useful for pain conditions came as a surprise.
Still, the existing evidence base for clinical effectiveness is poor quality, Dr. Coleman said in an interview. Rigorous trials are needed.
“It is a whole field that is just waiting for the U.S. to do something in terms of legalization so that we can actually study to see, does this make sense?” Dr. Coleman said.
Cannabis should not be used while pregnant
In a recent meta-analysis based on data from nearly 60,000 individuals, women who used marijuana during pregnancy were at increased risk for adverse neonatal outcomes such as low birth weight and preterm birth. Study author Greg J. Marchand, MD, of the Marchand Institute for Minimally Invasive Surgery, Mesa, Ariz., noted that the results will force some difficult decisions for mothers who use marijuana to treat medical problems, and that there may not be good substitute treatments for some of these conditions, especially chronic pain and anxiety.
Dr. Coleman disclosed investments in a cannabis exchange-traded fund. Dr. Blake and Dr. Marchand had no relevant financial disclosures.