Cancer clinicians are faced with high community demand for medicinal cannabis that goes beyond the level of evidence for its use in the prevention and management of chemotherapy-induced nausea and vomiting (CINV).
According to a Perspectives article in the MJA, the dilemma highlights the need for new and high quality clinical trial data to support – or challenge – its prescription.
The article, authored by medical oncologists Dr Antony Mersiades, Professor Martin Stockler, Professor Ian Olver and Dr Peter Grimison, notes that only 34 doctors had signed up to be registered prescribers of medicinal cannabis by mid-2018.
The low numbers were not particularly surprising given the limited evidence for the drug in studies ‘compromised by small sample sizes and outdated antiemetic control arms’.
While recent legislation allows prescription of medicinal cannabis for a limited number of indications, it seems clinicians do not feel comfortable prescribing the drug without corroborating evidence.
The authors said some international cancer guidelines, such as those from the European Society of Medical Oncology, make no recommendations at all regarding medicinal cannabis.
Others such as the American Society of Clinical Oncology (ASCO) conclude the current evidence is ‘insufficient for a positive recommendation’, while local TGA guidance recommends medicinal cannabis only for intractable symptoms where standard therapies have failed.
The MJA article said in 2017 ASCO recommended the addition of the antipsychotic drug olanzapine to standard antiemetic regimens following the results a phase 3, placebo-controlled, randomised trial.
“We argue that evidence from high quality trials similar in design to the olanzapine trial, demonstrating the efficacy and safety of medicinal cannabis for the prevention and management of CINV, is needed before most clinicians are willing to prescribe this class of medications widely in Australian clinical practice.”
The CannabisCINV trial of adding an oral tetrahydrocannabidiol extract to guideline-consistent antiemetics in the secondary prevention of CINV is currently underway in New South Wales.
“The results of such clinical trials will provide guidance to clinicians regarding appropriate use in specific indications, product selection, dosage and titration, and appropriate monitoring of both efficacy and safety,” they conclude.