Our results showed that the most common target symptoms patients reported taking cannabis products to help with were pain (58%), insomnia (42%), anxiety (36%), and nausea (33%). The results of this study are strikingly similar to two 2019 reports from the US. One report described a retrospective review of ambulatory palliative care clinic patients from New Hampshire and Vermont, and found a 27% current cannabis use rate, primarily for medical purposes. Patients were often treating multiple symptoms: pain (59%), anorexia (19%), insomnia (17%), nausea (16%), anxiety (10%) and depression (6%) . It would be expected that a palliative care population would be more likely to be symptomatic than our unselected cancer centre-attending population, and therefore be more likely to use medical cannabis, yet our study reported the same prevalence and reasons for use. Very similar results were reported in an ambulatory Seattle cancer patient study .
Our results showed that Current Users often took multiple forms of cannabis products, but used oils the most (70%) followed by smoking (64%), eating (48%), vaporizing (33%) and topically (29%). Consistent with our findings, a similar US study of cancer centre patients showed that the prevalence of using cannabis via inhalational and oral routes were equal .
Prior Medical Users reported multiple reasons for stopping taking cannabis, including ineffectiveness; intolerable side effects; and safety, and were slightly older (64 yrs) than Current Users (62 yrs). A 2017 systematic review reported that cannabinoids were less effective in managing chemotherapy side effects in older patients than in younger patients . Participants in clinical trials using fixed doses of cannabis-based products also consistently report multiple side effects . Our results with respect to side-effects and stopping taking cannabis are consistent with these studies.
The similarity in results between studies conducted in the US and Canada suggest that other countries considering legalization can expect similar patterns.
Comparison between before and after legalization surveys
Comparing our two surveys, we found that legalization was associated with a 26% increase in the prevalence of current cannabis use, from 23·1% to 29·1% (p = 0·01). One explanation for this increase might be that in the run-up to legalization news and media outlets were filled with articles about dispensaries opening and closing, [18, 26, 27] products available, [28, 29], and new research [30,31,32,33], which may have emboldened more patients to try cannabis. Despite both surveys being anonymous, they may also have felt more comfortable disclosing recreational motivation for use.
Though there are places where both medical and recreational access to cannabis are legal, we are not aware of any data from other jurisdictions legalizing access to recreational cannabis in the setting of a separate established medical supply system.
Despite the increase in current users, the choice of cannabis products and reasons for taking them remained much the same between both surveys. The high frequency of reporting use for multiple symptoms strengthens the suggestion that cannabis products should be further studied for potential to reduce polypharmacy in symptomatic cancer patients. Use of cannabis as a form of cancer treatment also remained one of the most common reasons for cannabis use between surveys, and is concerning considering the lack of good clinical trial evidence for any survival benefit from cannabinoid use in cancer.
Our survey reported that only one third of current users who reported using cannabis for medical purposes had the medical authorization necessary for accessing the official medical access system.
Our study identified some problems that impacted medical users immediately following recreational legalization. We found that unlicensed dispensaries and other illegal sources were much more commonly used than the legal medical system, despite their lack of reliable labelling and absence of quality control. The results showed an increase in the prevalence of current cannabis use and also in problems accessing medical cannabis after legalization.
There were multiple reported barriers to use of the legal medical access system, reported by both survey cohorts. Patients who wished to buy high quality legal medical cannabis had to negotiate the online system of access, including getting a medical authorization and waiting for processing of their registration. Respondents from the second survey identified the lack of legalization of certain products (primarily edibles), as their reason for preferring to continue to use illegal sources. Other reported barriers included the need to have a credit card and a stable address for delivery of product, and also difficulties in deciding what to order without the benefit of face-to-face interaction with a salesperson. Medical users’ access to appropriate products may also have been impeded by the fact that staff in recreational dispensaries are prohibited by law from providing medical advice.
The complexities of having two different licensing systems, and confusion between medical and recreational use made it difficult for patients and health care providers to figure out where to access reliable information and product suitable for medical purposes. It should be mentioned that BC was not unique in this respect in Canada [17, 34].
Similarly, respondents from the second survey identified the lack of legalization of certain products (primarily edibles), as their reason for accessibility barrier.
Implications and suggestions
Other jurisdictions planning to legalize recreational cannabis should consider the impact it might have on medical cannabis users. Medical and recreational use of cannabis often overlaps, at least in cancer patients, and it is concerning that many patients report believing/hoping that cannabis might help treat their cancer. Though much clinical research remains to be done, there is sufficient information available from credible sources (e.g. Health Canada) about doses, indications for medical use, and potential harms for appropriate guidance be created that should be made available in all vendor locations, irrespective of vendor focus.
Strengths and limitations
Results of this study provide new insights into cannabis use among cancer patients in British Columbia. This study is the first to provide data on the impact of recreational legalization on medical users. Strengths of this study include the close comparability of characteristics among participants in both cohorts. Open-ended questions in the survey allowed participants to share their experience with regards to barriers in obtaining cannabis, which added depth to understanding of the data.
As with all surveys, those that responded to the survey may not be representative of the surveyed population, thus our 27% response rate could reflect a sampling bias. The close matching of the demographics of respondents to the two consecutive surveys however gives us confidence that the differences demonstrated between the two cohorts’ responses reflect actual change. As the data was collected by self-report, and despite the surveys being anonymous, there may have been more openness in reporting recreational motives for cannabis use in the second cohort, with legalization of recreational use reducing stigma. There may also have been a recall bias about respondents’ prior cannabis use.
Another limitation is that there was no control group, and it is possible that the differences seen between the two cohorts may have been due to factors other than recreational legalization. The time difference was however only 5 months.
Though unlikely to have been a major confounder, there was potential for confusion about the definitions of routes of ingestion between our two survey cohorts that we were not aware of at the time the surveys were designed and tested by our patient partners. At the time of the post-legalization survey, gel capsules filled with oil were just becoming available legally and could possibly have been classified by some respondents as “edibles” rather than oils, whereas most “edibles” available illegally to the pre-legalization cohort were in the form of cookies, brownies and candies which were (and remain) illegal. Also, legally obtained oils could conceivably have been compounded for topical use by the respondents.