Medical cannabis and opioid use in patients with stage IV cancer

14th February 2022

While a diagnosis of cancer can mean a lot of things, and vary greatly from case to case, one thing is certain: the management of symptoms (of both the disease itself and associated treatments) is a crucial aspect of care. Pain, nausea, and anxiety are all common symptoms that can be difficult to manage effectively.

However, a growing body of evidence has supported the perception that medical cannabis may have a positive effect on a number of these symptoms.

Since 2000, over 20 studies have assessed the impact of medical cannabis on a variety of cancer-associated symptoms. Two large registry studies, each recruiting over 4,000 patients each showed that medical cannabis patients with cancer reported a clinically important improvement in symptoms, as well as seeing a reduction in the use of opioids and other supportive medications.  

Despite growing evidence to support the usefulness of cannabis-based products in the treatment of symptoms associated with cancer and cancer treatments such as chemotherapy, there remains a distinct lack of recommendation and prescription within the medical community. In fact, one US study showed that three-quarters of patients asked for information regarding cannabis from their cancer care team, yet only 15% of patients received it. 

Another pilot randomised, controlled trial of “early vs delayed start medical cannabis in cannabis-naïve patients with a variety of advanced cancers aimed to assess the safety and impact of medical cannabis on cancer-related pain and opioid use. Other aims of the study were to identify overall patient satisfaction with medical cannabis treatment, the feasibility of doing interventional trials with a state-sponsored cannabis program, and a suggested dose escalation strategy for medical cannabis products.  

Design and Methods of the Study 

The trial was open to patients who were at least 18 years of age who had been diagnosed with incurable or stage IV cancer, had used any opioids within 1 month of starting the trial had an ECOG performance status of≤2 and a life expectancy of at least 3 months, and were eligible to register with the Minnesota medical cannabis program (MMCP). 

A total of 30 eligible patients were randomised to either early cannabis (EC, n=15) or delayed cannabis (DC, n=15), however, only nine patients in each group were analysed. The EC group were given up to three months of medical cannabis through the MMCP at no cost, whereas the DC group received standard oncology care without cannabis for three months, and then offered a three-month trial of cannabis treatment at no cost.  

Validated symptom surveys with patient-reported symptom monitoring were used on a monthly basis in addition to a pain log and a medication diary where participants listed all of the analgesic and opioid medications that they were using; these were used to calculate a monthly oral morphine equivalent (OME).  

On average, the amount of THC dispensed per patient each month was almost twice that of CBD (34.4mg THC vs 16.6mg CBD). 

Results of the Study 

Pain Perception and Opioid Use 

Evidence suggests that medical cannabis may have the potential to improve pain while also lowering opioid use – two important goals for both cancer patients and clinicians. In order to determine the effects of cannabis on these two considerations, the researchers analysed pain and total OME over the first three months of the trial in all patients.  

Overall, baseline pain scores and personalised pain goals were similar for all patients. Overall mean pain scores from study entry to 3 months also remains similar, however, the number of patients who reported meeting their personalised pain goals increased from 2/9 to 4/9 (44%) in the early cannabis (EC) cohort, compared with a drop from 3/9 to 1/9 (11%) in the delayed cannabis (DC) cohort.  

During the 3-month study period, EC patients maintained stable levels of opioid utilisation, compared with DC patients where an average daily OME increase of 57% was observed. Furthermore, only patients in the EC cohort were seen to reduce their daily OME by at least 20%. 

Further Findings 

No adverse events were reported by the study participants. A total of 18 out of the 23 patients who utilised medical cannabis completed a close-out questionnaire. The average “negative impact” score reported by patients was 2.8 (1 = no negative effects; 4 = some negative effects; 7 = a great deal of negative effects). 

Although there was not a significant change in quality of life and key symptom scores over the 3-month period for EC users, patients did report a high degree of overall benefit from medical cannabis use at their study close-out. The average perceived benefit score was 4.9, with over one-third of respondents reporting a score of 7 (1 = no benefit; 4 = some benefit; 7 = a great deal of benefit).

Furthermore, 44% of patients who used cannabis reported that they would continue to purchase medical cannabis products through the state program after the trial. 

Researcher Conclusions 

The authors of this study conclude that “while we had significant patient drop-out mostly due to progressing cancer, we feel our trial design is feasible and should be considered by others wishing to do interventional studies with cannabinoids.” 

The data collected in this study support the findings of previous studies which suggest that cannabis may improve pain and minimise opioid use in both cancer and non-cancer settings.

The researchers stress the need for larger, prospective, pragmatic trials that incorporate cannabis in patients with similar cancer diagnoses, medical conditions, and cannabis products/doses to guide patients and cancer care providers on appropriate ways to effectively incorporate medical cannabis treatment plans in a cost-effective manner.  

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