Cannabis: high time for evidence-based policies - The Lancet Oncology
On Nov 8, while Americans elected Donald Trump as their next president, those in California, Maine, Nevada, and Massachusetts quietly voted for a different kind of change: legalisation of the use, sale, and consumption of recreational marijuana for adults over 21 years of age. Meanwhile, voters in North Dakota, Montana, Arkansas, and Florida legalised or reduced restrictions on medical (or prescription) marijuana. An ongoing controversy, marijuana legislation in 30 US states now conflicts with US federal law, in which marijuana is a Schedule I controlled substance with “no currently accepted medical use” and “high potential for abuse”, but brings these states in line with a global trend. For individuals with chronic pain and treatment-induced side-effects—both common in patients with cancer and cancer survivors—legalisation of marijuana use could change the treatment landscape, but evidence-based, rational policies must be a top priority.
Cannabis is legal for medicinal use or is decriminalised in more than 11 European countries, including the Netherlands, Belgium, and Spain. Australia legalised medicinal cannabis on Nov 1, 2016, and Germany and the Canadian federal government will follow in 2017. The US National Institutes of Health lists cannabis and cannabinoids (of which tetrahydrocannabinol [THC] is the most notable) as having potential for treating cancer-related symptoms caused by the disease itself or its treatment, although the evidence for its benefits and harms is conflicting. Randomised controlled trials testing cannabis and cannabinoids for the treatment of chemotherapy-induced nausea and vomiting and cancer-related pain have reported mixed results. Cannabis itself has not been approved for use by the US Food and Drug Administration (FDA). Dronabinol and nabilone, synthetic versions of THC, have been approved by the FDA to treat cancer-related and chemotherapy-induced nausea, but these are not derived from the native plant. This is in part because research on marijuana in the USA is highly restricted: it requires approval from three separate federal agencies and the drug must only be supplied by the National Institute on Drug Abuse. However, for a product rapidly becoming mainstream, clinical trials and basic research are crucial: the requirement for evidence of the benefits and risks of marijuana use will grow as access increases and regulations, including clear guidelines for safe and effective use, must be developed.
As well as improving quality and safety, legalisation could lift barriers to marijuana access and lessen social stigmas around its use. This could certainly benefit patients with cancer using marijuana products as part of their palliative and supportive care. However, there remain several potential pitfalls. The first is due to the peculiarity of the adoption of legalisation on a state-by-state basis rather than as federal law. Patients in legal states will have unrestricted access, while those living across state lines will be disadvantaged. This leaves opportunities for criminals to traffic marijuana to capitalise on unequal access. Consequently, law enforcement in states bordering those with legalised use will be difficult. And, is it possible, or ethical, to distinguish recreational users from patients with cancer who might have legitimate palliative care needs to ensure their access?
Taxes from the regulated sale of marijuana could be enormous; a 2015 report on the economic impact of legalisation in Colorado, USA, since Jan 2014 stated that “legal marijuana activities” generated “$121 million in combined sales and excise tax revenues”. The use of monies from taxes and other regulatory steps must be balanced with the needs of the public for affordable effective therapies. Using economic gains to improve health-care overall would be a worthy goal. Conversely, medicalisation of marijuana might lead to profit-based pricing that takes no account of, or artificially controls, supply and demand. In turn, this could promote black market trade and predatory practices on vulnerable people, two of the main evils legalisation is intended to combat.
One role of the government is to provide the best health care to its citizens. Government should, through judicious regulation, ensure that legal medicinal products are safe, efficacious, and cost-effective; that they are widely accessible; and that any potential profits are used to develop and improve the health system. Crucially, at a time when countries and governments are just starting to control the cancer epidemic caused by tobacco smoking, we must ensure that we do not legalise another inhalable product that could lead to another major public health crisis in 20 years' time. Questions arising over access, regulation, and cost must be handled appropriately to promote improved health and ensure equitable and appropriate access for all.