Medicinal uses for cannabis: Cancer chemotherapy

The drugs used to treat cancer are among the most powerful, and most toxic, chemicals used in medicine. They kill both cancer cells and healthy cells, producing extremely unpleasant and dangerous side effects. The most common is days or weeks of vomiting, retching, and nausea after each treatment. The feeling of loss of control is highly depressing, and patients find it very difficult to eat anything, and lose weight and strength. People find it more and more difficult to sustain the will to live, and many chose to discontinue treatment, preferring death to treatment.

Cannabis can be used as an antiemetic, a drug which relieves nausea and allows patients to eat and live normally. Despite great advances in the last few years of antiemetic research, cannabis is safer, cheaper and often more effective than standard synthetic antiemetics. Smoking cannabis can be more effective than taking it (or its synthetic derivatives such as Marinol) orally as patients it difficult to keep anything down long enough for it to have an effect. Smoking cannabis produces an immediate effect, and patients find it easier to control the dosage. Additionally the euphoric properties act as an anti-depressant, and the hunger and enjoyment of food properties ('the munchies') make weight gain easy, and these increase the chances of recovery.

The method by which chemotherapy generates nausea and vomiting is not entirely certain, although studies point to it being caused by receptor stimulation in the central nervous system or gastrointestinal tract. However, cannabis as an antiemetic seems to work via a different mechanism than the currently-used antiemetic drugs in this field (such as corticosteroids). It is therefore worthy of investigation whether a combination of cannabinoids and existing therapies may benefit the patient more than either of the two taken separately. It also suggests that patients who do not respond well to traditional antiemetic medications may find greater benefit with cannabis-based drugs.

A relatively large number of studies have been done on the anti-emetic properties of cannabis in regard to the negative effects of chemotherapy. Almost invariably cannabis (and some of its constituent cannabinoids) have been found effective. As a result of this, in 1985 the US FDA licenced synthetic THC (Dronabinol) for these symptoms. In the UK however it is not licensed in this way. It is actually possible to prescribe Dronabinol to patients in the UK, but only on an individual basis. This is very rarely done, perhaps not surprisingly given the large amount of administrative obstacles that need to be overcome.

However, in 1982 Nabilone (an analogue of delta-9-THC) was licensed in the UK to allow it to be prescribed for nausea following chemotherapy, as long as other treatment was ineffective and that it was solely used within a hospital environment.

In terms of efficacy, cannabis has several competitors as an antiemetic. However, the Institute of Medicine's 1999 report summed it up nicely when it stated that 'the critical issue is not whether marijuana or cannabinoid drugs might be superior to the new drugs, but rather whether there is a group of patients who might obtain added or better relief from marijuana or cannabinoid drugs'.

Both scientific research and testimonies of currently-criminalised users seem to state that this group of patients does indeed exist.

The treatment of nausea and vomiting is not the only way in which cannabis can help cancer sufferers. Both the analgesic (pain-relieving) and appetite-stimulating qualities of cannabis can make a patient's life both longer and far more bearable.

Scientific evidence

Several cannabis-related medications have been tested for their effects on nausea caused by chemotherapy, including delta-9-THC, delta-8-THC, Nabilone, Levonantradol and BRL-4664, as well as 'natural' cannabis

THC was almost always found to produce significant antiemetic properties. One of the first studies was by Sallan et al (1975). The study compared oil-based capsules containing THC given to 20 patients both before and after chemotherapy treatment. Fourteen of the patients found THC to be an effective antiemetic. Chang et al (1979) found that THC was an effective antiemetic to counteract the nauseous effects of the methotrexate medication used in chemotherapy, with 14 out of 15 patients reporting some relief of nausea and vomiting. Two years later Chang et al found that it was also effective in patients undergoing treatment with anthracyclines (which produce a higher level of emetic behaviour) albeit to a limited extent. Lucas et al (1980) gave THC to 53 patients to whom other treatments were unsatisfactory. 10 suffered no vomiting after chemotherapeutic treatment. Another 28 had more than a 50% reduction in vomiting.

Studies by Frytak et al (1979), Orr et al (1980) and Sallan et al (1980) showed a comparison between patients receiving the antiemetic drug prochlorperazine and THC. Typically oral THC was found to be of a similar efficiacy to prochlorperazine. Whilst comparing THC to metoclopramide, Gralla et al (1984) found that THC completely stopped vomiting in 13% of patients, and almost eliminated it in another 27%.

With regard to the lesser-studied variants of THC, McCarthy et al (1984) found that a metabolite of THC, 11-OH-THC was less effective as an antiemetic than THC. Razden (1986) however found that delta-8-THC completely prevented any emesis in 8 children undergoing chemotherapy. Moreover, delta-8-THC is significantly less psychoactive than delta-9-THC and very few side-effects were reported.

As stated, the synthetic cannabinoids Nabilone and Levonantradol have also been investigated (Steele et al 1980 and Tyson et al 1985 respectively). These produced similarly effective antiemetic results to THC. Herman et al (1979) found that medicating with Nabilone was significantly more effective that treatment with the standard antiemetic prochlorperazine.

Staquet et al (1981) investigated another THC homologue known as BRL-4664. This too showed some antiemetic effect.

Vincigeurra et al (1988) found that 78% of 56 patients with nausea who were resistant to standard drugs became symptom free through inhaling cannabis. All of these found that cannabis was either a 'moderately effective' or 'highly effective' form of therapy.

The method of administration for medicinal cannabis can be of importance. Firstly, patients suffering severe vomitting may not be able to keep orally-given cannabis down long enough to have effect. Inhalation, whether by smoking or other means, removes this obstacle, and studies such as Ohlsson's (1980) have shown that the effects of inhaled cannabis start much sooner (almost immediately) than if it is taken orally.