A provincial survey found 43% of cancer patients had used cannabis, with 18% using it recently, mostly for pain and nausea | Research

The takeaway

A survey of 1,987 cancer patients across four Canadian cancer centers found that 43% had ever used cannabis, 18% had used it in the past 6 months, and among recent users, 36% were new users citing cancer-related pain (46%), nausea (34%), and other cancer symptoms (31%).

Oncologists discussing cannabis with patients; medical cannabis program administrators; cancer patients considering cannabis for symptom management.

43% of cancer patients had used cannabis; 80% acquired it through friends, not dispensaries

What the researchers found

Researchers distributed surveys to 3,138 cancer patients across two comprehensive and two community cancer centers in a Canadian province, with 1,987 usable responses (63% response rate).

Lifetime cannabis use was reported by 43%, independent of age, sex, education level, or cancer type.

Cannabis was acquired primarily through friends (80%), with only 10% from regulated medical dispensaries.

Of 356 patients (18%) who used cannabis in the past 6 months, 36% were new users who started after their cancer diagnosis.

Reasons for recent use included cancer-related pain (46%), nausea (34%), other cancer symptoms (31%), and non-cancer-related reasons (56%, which could overlap with other categories).

Most users (81% of those with any use) had used dried leaves.

Why it matters

This is one of the most comprehensive assessments of cannabis use among cancer patients. The finding that 36% of recent users were new to cannabis after diagnosis shows that cancer itself is driving new cannabis uptake, while the low rate of dispensary use (10%) suggests most cancer patients are outside the regulated medical cannabis system.

The numbers in context

1,987 respondents (63% response rate). 43% lifetime use. 18% used in past 6 months. 36% of recent users were new users. Sources: friends 80%, dispensaries 10%. Reasons: pain 46%, nausea 34%, other cancer symptoms 31%, non-cancer 56%. 81% used dried leaves.

How the study worked

Anonymous survey distributed to cancer patients at four cancer centers across an entire Canadian provincial health jurisdiction. 3,138 distributed, 1,987 analyzed (63% response rate).

What this study cannot tell us

Cross-sectional survey with 63% response rate. Self-reported data subject to recall and social desirability bias. Canadian provincial sample may not generalize to other jurisdictions. Survey did not assess cannabis dose, frequency, or specific products used.

How to read the evidence

Moderate. Large provincial survey across multiple cancer centers with good response rate, though limited by self-report methodology.

When this study was published

Published in 2018, before full Canadian cannabis legalization in October 2018. Patterns may have shifted since legalization.

The bigger picture

The gap between patient cannabis use and medical system involvement is striking. With 80% acquiring through friends and only 10% through dispensaries, most cancer patients using cannabis are doing so without medical guidance on dosing, interactions with cancer treatment, or product quality.

Questions still open

Why do so few cancer patients access cannabis through medical channels? Would physician-guided cannabis use improve symptom management? Do cancer patients using cannabis have better or worse treatment adherence?

Common questions

Why do cancer patients use cannabis?

In this survey, the most common cancer-related reasons were pain management (46%), nausea (34%), and other cancer symptoms (31%). Many patients also cited non-cancer reasons (56%). Cannabis is used both for direct cancer symptoms and for treatment side effects like chemotherapy-induced nausea.

Is it safe to use cannabis during cancer treatment?

Cannabis can interact with some cancer treatments and medications. The fact that 80% of cancer patients in this study acquired cannabis from friends rather than medical sources means most are using it without guidance on potential interactions. Patients should discuss cannabis use with their oncology team.

Read the original research

Rates of cannabis use in patients with cancer.

Current oncology (Toronto, Ont.), 25(3), 219-225

View on PubMed ↗Publisher’s paper ↗

Citation

Martell, K; Fairchild, A; LeGerrier, B; Sinha, R; Baker, S; Liu, H; Ghose, A; Olivotto, I A; Kerba, M. (2018). Rates of cannabis use in patients with cancer.. Current oncology (Toronto, Ont.), 25(3), 219-225. https://doi.org/10.3747/co.25.3983