The claim that Cannabis can cure cancer is all over the Internet. Such promotion is regularly enhanced by announcements of VIPs that they intend to try Cannabis when affected by cancer.
As her back pain turned out to be caused by metastases from her earlier breast cancer, Olivia Newton-John now intends to complete a course of photon radiation therapy along with alternative therapies for improving her quality of life. “I decided on my direction of therapies after consultation with my doctors and natural therapists and the medical team at my Olivia Newton-John Cancer Wellness and Research Centre in Melbourne”, she said. Newton-John had been diagnosed with breast cancer in 1992. At that time, she initially tried acupuncture and homeopathy and only later underwent chemotherapy. Olivia Newton-John’s daughter, Chloe Lattanzi, has stated that her mother would now use cannabis oil to aid in her fight against cancer. Lattanzi owns a marijuana farm and said that her mother would use natural healing remedies plus modern medicine in addition to cannabis oil to help her battle the deadly disease for the second time.
So, how realistic is the assumption that Cannabis does anything for cancer patients? Cannabis produces a resin containing pharmacologically active compounds called cannabinoids. Some cannabinoids are known for their psychoactive properties. Cannabis has therefore been used for medicinal and recreational purposed since ancient times. Today, the recreational use of Cannabis is illegal in many states, including the UK.
The main active cannabinoids are delta-9-THC and cannabidiol (CBD); the latter compound may relieve pain, lower inflammation, and decrease anxiety without causing the “high” of delta-9-THC. Cannabis and cannabinoids have been studied in the laboratory and the clinic for relief of pain, nausea and vomiting, anxiety, and loss of appetite. There also is some evidence that they can alleviate the side-effects of cancer therapies. Two cannabinoids have even been approved by the regulators in some countries for the prevention and treatment of chemotherapy-related nausea and vomiting. Some test tube results have suggested that Cannabis can kill cancer cells. However, there are no clinical trials yet, and therefore not enough evidence exists to recommend that patients use Cannabis as a treatment for cancer.
The possibility that Cannabis might be useful for cancer patients currently attracts much original research. The most recent review states that “favorable outcomes are demonstrated for chemotherapy-induced nausea and vomiting and cancer-related pain, with evidence of advantageous neurological interactions. Benefit in the treatment of anorexia, insomnia and anxiety is also suggested. Short- and long-term side effects appear to be manageable and to subside after discontinuation of the drug. Finally, cannabinoids have shown anti-neoplastic effects in preclinical studies in a wide range of cancer cells and some animal models. Further research is needed before cannabis can become a part of evidence-based oncology practice.”
Similarly, the conclusions by our ‘CAMcancer’ initiative were cautious: ” The antiemetic efficacy of the cannabinoid dronabinol (THC), when compared to standard antiemetics that were in use before the development of 5-HT3 antagonists for chemotherapy-induced nausea and vomiting, has been established in a meta-analysis. The question of whether cannabis-based medicines have a place in the era of modern antiemetic medication, e.g. for patients with refractory nausea and vomiting despite antiemetic prophylaxis according to current standards, remains uncertain but warrants further research. Limited evidence is available to support the use of cannabis-based medicines in the therapy of radiotherapy-related nausea and multifactorial nausea in advanced cancer patients. The use of cannabis-based medicines for appetite loss and other symptoms associated with cancer cachexia is still unclear at present, since trial results have not only varied widely but also been criticised for the methodology employed (including diversity in stages of cachexia in the patients included and possibly too a low dose of THC/medical cannabis). For cancer pain, several randomised controlled trials of cannabis-based medicines in cancer patients with various pain syndromes have indicated an analgesic effect comparable to weak opioids. The role of cannabinoid medicines as add-on medication for pain that is insufficiently relieved by strong opioids is currently being investigated in several clinical studies and has shown some promising results so far.”
So, the evidence suggests that Cannabis might be helpful in the supportive and palliative treatment of cancer by reducing some of the symptoms from which cancer patients may suffer. But there is no good evidence to show that it can change the natural history of any type of cancer. Even with the symptomatic use of Cannabis, we need to consider at least two caveats.
Firstly, we have no good evidence to suggest that Cannabis is significantly more effective than conventional therapies. A Cochrane review, for instance concluded that ” Cannabinoids can lead to an increase in appetite in patients with HIV wasting syndrome but the therapy with megestrol acetate is superior to treatment with cannabinoids. The included studies were not of sufficient duration to answer questions concerning the long-term efficacy, tolerability and safety of therapy with cannabis or cannabinoids. Due to the sparse amount of data it is not possible to recommend a favoured use of cannabis or cannabinoids at this point.”
Secondly, the Cannabis trials tend to be of low quality. Another Cochrane review concluded that “Cannabis-based medications may be useful for treating refractory chemotherapy-induced nausea and vomiting. However, methodological limitations of the trials limit our conclusions and further research reflecting current chemotherapy regimens and newer anti-emetic drugs is likely to modify these conclusions.”
Back to Olivia Newton-John; her case is, I think, telling. It seems that, by initially using alternative therapies instead of conventional treatments for her breast cancer in 1992, she worsened her prognosis. Now that the cancer has returned, she has learnt her lesson and opts for the best conventional oncology can offer her. Yet, her liking for alternative medicine has not disappeared completely. This confirms what I have observed all too frequently: for many of its fans, alternative medicine is a belief system that is largely untouchable by evidence.