Medicinal cannabis can safely relieve pain and reduce the number of other medicines cancer patients take, researchers have suggested.

New research was carried out involving 358 patients with cancer, who were part of the Quebec Cannabis Registry, and who provided information on pain, symptoms, other medication and morphine doses at three, six, nine and 12 months.

Pain was the most frequently reported symptom that prompted a prescription of medicinal cannabis in 73% of patients with genitourinary, breast, and bowel cancer.

The study found that products with an equal balance of the active ingredients tetrahydrocannabinol (THC) and cannabidiol (CBD), rather than a dominance of either one, seem to be particularly effective.

The findings suggest that medicinal cannabis is a safe and complementary treatment in patients who do not find relief from conventional medicines.

Reporting in BMJ Supportive and Palliative Care, the researchers found statistically significant decreases on validated pain scales at three, six and nine months for worst and average pain intensity, overall pain severity, and the interference of pain with daily life.

The total number of drugs taken also fell consistently at all check-ups, while opioid use fell over the first three check-ups.

Cannabis also seemed well tolerated by patients with only 15 moderate to severe side effects reported by 11 individuals, 13 of which were regarded as minor, such as sleepiness. Five patients stopped taking it because of side effects.

There were two serious side effects (pneumonia and a cardiovascular event) reported but assessed as unlikely to have been linked to medicinal cannabis use.

But the authors stressed the observational nature of the study and the fact a significant number of patients were lost to follow up, and more research with control groups is needed to assess effectiveness.

Last year, a national review of innovation in this sector concluded that GPs should be allowed to prescribe medicinal cannabis.

It also advocated that a national trial for GP prescribing of cannabinoid-based medicinal products should be rolled out with systematic data collection to inform future guidelines.

A Department of Health and Social Care spokesperson said: ‘Licensed cannabis-based medicines are funded routinely by the NHS where there is clear evidence of their quality, safety and effectiveness.

‘Like any other medicine, unlicensed cannabis-based products for medicinal use must be proved safe and effective before they can be considered for routine NHS funding.

‘We are working closely with partners to establish clinical trials to test the safety and efficacy of more cannabis-based products for medicinal use to inform future NHS funding decisions.’

In September, Scotland joined the rest of the UK in licensing cannabis-based Sativex to treat adults with moderate to severe spasticity due to MS, where other treatments haven’t worked.

This article first appeared on our sister site, Pulse.