Cancer patients often experience a range of physical and psychological symptoms related to their disease and its treatment. These symptoms can include pain, nausea, anxiety, depression, and sleep disturbance, among others.
While there are many medications available to address these symptoms, some patients turn to cannabis as an alternative or complementary therapy. Studies suggest that cannabis use can provide relief for many cancer-related symptoms, including pain and sleep disturbance. Furthermore, there is emerging evidence that cannabis use may also have positive effects on cognitive function.
From a chemical standpoint, cannabis contains over 100 different compounds known as cannabinoids. The two most well-known cannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC is the primary psychoactive compound in cannabis, responsible for the “high” associated with its use. CBD, on the other hand, does not produce psychoactive effects and has been shown to have anti-inflammatory and analgesic properties.
In the body, cannabinoids interact with a system known as the endocannabinoid system (ECS), which plays a role in regulating many physiological processes, including pain perception, mood, and sleep. The ECS consists of two main receptors, CB1 and CB2, which are found throughout the body, including in the brain, immune system, and peripheral tissues.
Research has shown that cannabinoids can modulate pain perception by activating CB1 receptors in the spinal cord and brain. THC, in particular, has been shown to be effective in reducing cancer-related pain. In a randomized controlled trial of cancer patients with chronic pain, those who received THC reported greater pain relief than those who received a placebo.
Cannabis use has also been shown to improve sleep in cancer patients. In a study of cancer patients with insomnia, those who used cannabis reported significant improvements in sleep quality and duration compared to those who did not use cannabis. Additionally, cannabis use has been associated with a reduction in nightmares, which can be a common symptom of post-traumatic stress disorder (PTSD) in cancer patients.
Emerging research suggests that cannabis use may also have positive effects on cognitive function in cancer patients. In a study of patients with glioma, a type of brain cancer, those who used cannabis had improved verbal fluency compared to those who did not use cannabis. Another study found that long-term cannabis use was associated with increased blood flow to certain areas of the brain, suggesting a potential neuroprotective effect.
From a biological standpoint, cannabis use may also have effects on DNA. Studies have shown that cannabinoids can influence gene expression and alter DNA methylation patterns, which can affect the expression of genes involved in inflammation, apoptosis, and other processes. However, the clinical implications of these findings are still unclear.
While cannabis use can provide relief for many cancer-related symptoms, it is not without risks. Cannabis use can have side effects, including dizziness, dry mouth, and cognitive impairment, and may interact with other medications. Additionally, cannabis use can have psychological effects, including anxiety and paranoia, particularly at higher doses or in individuals with a history of mental health issues.
Anew study is among the first to explore associations of acute and sustained legal market cannabis edible use, including the use of both THC and CBD, with changes in pain, cognition, and quality of life in a group of cancer patients. Patients reported improvements in pain, sleep quality, and subjective cognitive function following a two-week ad libitum cannabis use period, as well as reductions in pain intensity, increases in feelings of subjective high, and some decreases in cognitive function following acute cannabis use.
The observational nature of the study also allowed a window into the kinds of products cancer patients select, how frequently they choose to use their products, and what doses of THC and CBD they choose to take. Participants in the present study used a variety of edible forms of cannabis and a wide range of doses of both THC and CBD. This is perhaps somewhat unexpected given the rapidly growing interest in CBD over the past five years .
A significant effect of CBD use on baseline pain intensity was observed, such that greater CBD use over the two-week period was associated with greater pain intensity at baseline, suggesting that individuals with higher pain intensity at baseline may have intentionally selected products higher in CBD or consumed more CBD over the two weeks to cope with these heightened pain levels.
A greater understanding of how cancer patients come to make decisions around cannabis use and how their expectancies may vary by cannabinoid content will be critical in order to develop guidance for both clinicians and patients who wish to use cannabis for palliative cancer care.
Improvements in pain intensity and pain interference were observed following sustained cannabis use, as well as improvements in pain intensity following acute use. Interestingly, a time X CBD ingested interaction emerged in the two-week models of pain intensity, with greater CBD use during the two-week ad libitum period being associated with steeper improvements in pain intensity. Notably, no moderating effect of CBD use was observed during the acute use appointment.
Two early clinical trials in cancer patients that utilized THC oil capsules demonstrated a trend toward progressive pain relief with increasing doses of THC over a six-hour period , as well as significant improvements in pain following 20 mg of THC compared to placebo over a seven-hour period , although adverse reactions to this dose were observed in this group of predominantly inexperienced cannabis users .
In addition, a two-week trial of oromucosal sprays showed improvements in pain compared to placebo following the use of a combination of CBD and THC spray, but not with a THC-only spray . More recent trials have yielded mixed results on the effectiveness of cannabinoids for pain [75, 76], but the picture that emerges from across the literature suggests that THC and CBD may influence pain relief over different time courses. Pharmacokinetic research will be key to addressing these potentially differential effects of THC and CBD depending on the time course of sustained versus acute use.
Improvements in sleep quality following sustained cannabis use were observed, with higher CBD use during the two-week ad libitum use period being associated with steeper improvements in sleep quality. A recent meta-analysis that included five randomized controlled trials of oromucosal sprays containing cannabinoids found a very small improvement in sleep disturbance compared to placebo in individuals living with chronic cancer pain . Objective measures of sleep in the context of carefully controlled sleep studies would be ideal for better understanding the differential effects of THC and CBD across the full range of measures of sleep quality.
Two weeks of ad libitum use in the present study was associated with patient reports of improvements in subjective cognitive function. Some objective measures of cognitive function also improved, including reaction times for both congruent and incongruent trials on the Stroop task.
Consistent with the literature on pain and cognitive function, an exploratory analysis supported a negative association, such that increases in pain were associated with subjectively worse cognitive function. Given widespread concern—by both clinicians and patients themselves—about decrements in cognitive function associated with cancer treatment, a potential indirect role of cannabis use in improving subjective cognitive function is an intriguing finding to pursue.
Also consistent with past research, some impairments following acute administration on objective cognitive performance were also observed, such that the Stroop effect on reaction time and error rate for incongruent trials both increased (i.e., got worse).
Limitations of the present study include a small sample size which limited statistical power to investigate demographic or other moderators in the analyses. From an internal validity perspective, the lack of random assignment to product condition and the lack of a placebo-control condition are clearly problematic for any causal conclusions regarding the influence of cannabis on any of the outcomes tested in this study. In addition, the study was interrupted by the COVID-19 pandemic, requiring the study to transition to a remote modality to continue data collection.
The generalizability of the conclusions of the present study is limited by the largely white sample and by the restriction on the use of cannabis edibles. There is evidence that cancer patients also use inhaled cannabis products [7, 78]. The short two-week timeframe may have limited the capacity of the present study to observe changes following sustained cannabis use. The inclusion of participants with different cannabis use histories and undergoing different treatments may have influenced participant response to acute and sustained cannabis use.
Despite its limitations, this study benefits from increased external validity via its naturalistic design, which allowed participants to select and use legal market edible cannabis products in a manner and environment that reflected their own preferences, needs, and typical use behaviors. The study’s inclusion of multiple cancer types also allowed for a greater age range of participants and an equal representation of sex, which may not be feasible when restricting eligibility to certain cancer types (e.g., breast, prostate).
reference link: https://www.explorationpub.com/Journals/em/Article/1001138
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