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  • A new study finds cannabis can help relieve cancer pain.
  • Pain is a common symptom among people with cancer. It can be caused by cancer, cancer treatments or other factors.
  • Opioids are used for controlling more severe pain, but they have a number of side effects, such as nausea, drowsiness and constipation.

Medicinal cannabis can relieve cancer pain and reduce the need for opioids and other medications, a new study suggests.

In addition, products with a balance of the active compounds delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) — versus those dominant in either one — were more effective, the results showed.

“Our data suggest a role for [medicinal cannabis] as a safe and complementary treatment option in patients with cancer [who fail] to reach adequate pain relief through conventional analgesics, such as opioids,” the researchers concluded.

The study was published May 3 in the journal BMJ Supportive & Palliative Care.

Pain is a common symptom among people with cancer. It can be caused by cancer, cancer treatments or other factors.

To help control a person’s pain, a doctor may prescribe acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), opioids or other drugs.

Opioids are used for controlling more severe pain, but they have a number of side effects, such as nausea, drowsiness and constipation.

Even with the availability of opioid medications, research shows that about one in four people with cancer-related pain don’t receive adequate treatment for the intensity of their pain.

As a result, many people with cancer seek out alternative ways to control their pain, including cannabis.

To better understand if medicinal cannabis can safely and effectively relieve cancer pain, researchers studied the treatment responses of 358 adults with cancer over a period of 3.5 years. Data came from the Quebec Cannabis Registry in Canada.

The average age of the patients was 58, and over half were female. The most common cancer diagnoses were genitourinary, breast, colorectal, lung and blood-related.

Over 72% of patients reported having pain symptoms, with a small number of people reporting nausea, anxiety, insomnia or other symptoms.

Patients were authorized a range of cannabis products — 25% used THC-dominant products, 38% used THC:CBD-balanced products and 17% used CBD-dominant products. Over half of patients took the product by mouth.

Patients’ pain symptoms decreased over the year-long follow-up, researchers found. This included worst and average pain intensity, overall pain severity and a measure of how much the pain interfered with daily life.

Products that had a balance of THC and CBD were associated with stronger pain relief compared to THC-dominant or CBD-dominant products.

Angela Bryan, PhD, a professor of psychology and neuroscience at the University of Colorado Boulder, who was not involved in the study, said the stronger effect of a balanced product makes sense.

Traditionally, people used the whole plant — rather than extracts — which contains not just THC and CBD, but a number of other active compounds.

“There’s something about the whole plant working together that might be the sweet spot for effectiveness,” Bryan told Healthline. “But we need a lot more data and really good plant scientists to help us with that side of things.”

The authors of the new study also found that the total number of medications that patients took decreased at each quarterly check-up. Opioid use was lower at the first three check-ups.

In addition, medicinal cannabis seemed to be safe, the study found, with sleepiness and fatigue the most commonly reported side effects.

Eleven patients reported moderate to severe side effects, and five stopped taking medicinal cannabis due to the side effects.

“The particularly good safety profile of [medicinal cannabis] found in this study can be partly attributed to the close supervision by healthcare professionals who authorized, directed and monitored [the] treatment,” the researchers wrote.

This is an observational study, so it can’t show a direct relationship between cannabis use and lower pain symptoms or medication use. In addition, many patients could not be followed for the entire study, and information on medications used by patients was limited.

Other research supports the use of cannabis for pain relief. Bryan said even in studies that use a variety of cannabis products, patients still find some relief from pain.

“This suggests that there’s some reliability, in terms of the effectiveness that people experience with cannabis,” she said, “and it doesn’t really seem to matter what preparations they use.”

In a study published April 26 in the journal Exploration in Medicine, Bryan and colleagues found that cancer patients who used cannabis products had lower levels of pain, slept better and saw improvements in some aspects of thinking.

The study involved 25 cancer patients who used cannabis over two weeks.

Patients used a variety of cannabis products, including chocolates, gummies, tinctures, pills and baked goods, with a range of potencies and varying ratios of THC and CBD.

Researchers assessed patients’ pain levels, sleep patterns and cognition at the start of the study, then again shortly after cannabis use and after two weeks of sustained use.

The assessments were done in a “mobile laboratory” that researchers drove to each patient’s home.

Patients purchased the cannabis products themselves and used the products in their own home. This is because of legal restrictions on how researchers can study cannabis use by people.

Within an hour of cannabis use, patients’ pain symptoms decreased, but they had some impairment of cognition and felt “high.”

However, after two weeks of sustained use, patients reported improvements in pain, sleep quality, and some aspects of cognitive function such as reaction time.

The effect of cannabis use on cognition was surprising, Bryan said, because both cannabis and chemotherapy have been linked with impaired thinking.

It’s not clear how cannabis might improve cognition in cancer patients, she said, suggesting that cannabis might relieve some of the side effects of cancer treatment.

“Chronic inflammation that occurs with cancer is responsible for a lot of the negative side effects of cancer treatments,” said Bryan, “so there might be some direct anti-inflammatory effect [of cannabis] on the brain.”

There could also be indirect effects. They found that people whose pain decreased more had greater improvements in their cognition.

“It wasn’t a huge effect, but it was reliable,” Bryan said, “so it suggests that part of the reason people feel like they can think more clearly is because they’re in less pain.”

They also found that people who took products with higher levels of CBD reported larger improvements in pain intensity and sleep quality.

Bryan said they are planning a larger randomized controlled trial that will test the impact of hemp-derived CBD on patient’s pain.

This type of cannabis product is legal at the federal under the 2018 Agriculture Improvement Act, which allows researchers to administer it to patients in a randomized trial.

“So we’re going to be able to take a much closer and careful look at that association [between cannabis use and pain relief],” Bryan said.