Leading US body, the National Cancer Institute is set to fund further research to gain a “deeper understanding” of the effects of cannabis on cancer.
Despite an estimated one in four cancer patients in the US using cannabis to manage their condition, clinical research into its efficacy and risks remains limited.
But as this field of research begins to gain momentum, the US federal government is set to provide funding to promote further studies.
In a notice of special interest released last week (5 May), the National Cancer Institute (NCI) invited research applications that examine the mechanisms of cannabis and cannabinoids in cancer biology, cancer interception, cancer treatment and resistance and management of cancer symptoms.
With more and more states legalising cannabis, both for medicinal and recreational purposes, the use of cannabis has grown significantly. A 2019 survey estimated that 48 million United States individuals aged 12 years or older had used cannabis in the past year, an increase of 87 per cent from 2002.
Among cancer patients, cannabis use has also increased, with a quarter of patients thought to take cannabis to manage common symptoms like anorexia, nausea and pain. As research continues to lag behind the growing interest in cannabis as an alternative therapy, the National Cancer Institute said the notice aims to “promote research in understanding the mechanisms” by which cannabis affects cancer symptoms, biology and treatment.
The notice highlighted a number of under-explored areas of research, including cancer risk, cancer biology, cancer treatment and the links between cancer and the endocannabinoid system.
The current research on associations between cannabis use and cancer risk have have yielded limited and inconsistent results, the NCI said.
The agency noted that while cannabis smoke generates many of the same carcinogens as tobacco, studies have not shown a link between cannabis smoking and lung cancer. While there is some preliminary evidence suggesting an increased risk of testicular cancer amongst cannabis users, studies of other cancer types are limited.
The agency also said a “deeper understanding is needed about how the tumour-promoting and suppressive mechanisms of cannabinoid signalling influence cancer biological processes”.
A key piece in the puzzle is the endocannabinoid system which has been found to regulate processes including cell proliferation, motility and survival. These pathways are often dysregulated in cancer, the NCI said.
Research so far has produced mixed results. For example, a study using mouse models of a type of breast cancer, found CB2 enhances tumour growth and metastasis. Other cancer models, however, have found that cannabinoids can suppress tumour formation.
The notice stated: “Cancer cell line experiments show that THC and CBD can mediate many anti-tumour effects, including inducing apoptosis and inhibiting cell proliferation, invasion and angiogenesis.
“These anti-tumour activities have led to early clinical testing of THC and CBD for glioblastoma and prostate cancers. While preclinical studies show differing effects of cannabinoids on cancer cells, deeper understanding is needed about how the tumour promoting and suppressive mechanisms of cannabinoid signalling influence cancer biological processes.”
In a UK phase I trial in glioblastomas last year, the cannabis-based mouth spray Sativex was found to be tolerable in combination with chemotherapy, with the potential to extend survival. The research project has now progressed to a phase II trial which launched across 15 NHS hospitals in 2021.
The notice said studies that “integrate expertise from multiple disciplines, incorporate state-of-the-art, human-relevant models (e.g organoid or patient-derived xenograft models) and utilise advanced technologies and methods” are strongly encouraged to apply.
A full list of areas of research that the NCI is particularly interested in can be found here
How THC and CBD work together in the brain – new study
New findings on how CBD and THC – the psychoactive compound in cannabis – affect the brain when administered together, could help to develop new cannabinoid therapeutics, scientists say.
A study has investigated the impact on the brain of CBD and THC, both as separate entities and when co-administered.
Researchers at University College London (UCL) analysed data from previous studies, including one which used functional Magnetic Resonance Imaging (fMRI) technology to measure brain activity in participants taking CBD and THC.
For the first time, they explored the response of the striatum region of the brain – a major part of the motor and reward systems. This is a critical component of numerous aspects of cognition, including motor and action planning, decision-making and motivation.
One study compared inhaled cannabis containing 8 mg THC, 8 mg THC + 10 mg CBD and a placebo. It showed strong disruptive effects of both THC and THC + CBD on connectivity in the associative and sensorimotor networks.
However it also identified a “specific effect of THC” in the limbic striatum network which was not present in the THC + CBD condition.
In a second study, testing oral 600 mg CBD versus placebo, CBD increased connectivity in the associative network, but produced only relatively minor disruptions in the limbic and sensorimotor networks.
The study concludes that THC “strongly disrupts striato-cortical networks” but that this effect is mitigated by the co-administration of CBD.
It states: “Oral CBD administered has a more complex effect profile of relative increases and decreases in connectivity.
“The insula [part of the brain implemented in diverse functions including emotions and self-awareness] emerges as a key region affected by cannabinoid-induced changes in functional connectivity, with potential implications for understanding cannabis-related disorders, and the development of cannabinoid therapeutics.”
This is the first report in human subjects of data from THC, THC + CBD and CBD use achieved “using a unified set of analysis methods, and with all comparisons performed in a placebo-controlled, double-blind design”.
Read the full report here.
Five new cannabis studies to have on your radar
The latest scientific papers exploring cannabis and its impact on health and society.
Get up to date with the latest cannabis-related research from across the globe.
Over the past few weeks, we’ve seen papers published around inaccurate labelling, the effects of cannabis on Covid-19, the impact of legalisation in Uruguay and how cannabis users might require more sedation during medical procedures.
Read on for five significant studies to dive into.
Lower Covid-19 severity among cannabis users
The researchers aimed to assess whether current cannabis users hospitalised for Covid-19 had different outcomes compared to non-users through a retrospective analysis of 1,831 patients admitted to UCLA Medical Centre in California.
Analysis of the data found that cannabis users had significantly better outcomes compared to non-users, shorter hospitalisation, lower ICU admission rates and less need for mechanical ventilation.
Interestingly, the researchers also found that active users had lower levels of inflammatory markers upon admission than non-users.
The authors of the study concluded: “This retrospective cohort study suggests that active marijuana users hospitalised with COVID-19 had better clinical outcomes compared with non-users. However, our results need to be interpreted with caution given the limitations of a retrospective analysis.
“Prospective and observational studies will better help elucidate the effects of marijuana use in COVID-19 patients.”
Cannabis users require more sedation for endoscopy
According to new research, patients who use cannabis required higher levels of sedation during gastric endoscopies than non-users.
As cannabis is legalised in more places and usage continues to rise, researchers in Canada said clinicians should be aware of patients’ cannabis consumption and prepare themselves for increased sedation and the risks that come with it.
The authors of the study conducted a prospective cohort study of 419 adult outpatients undergoing endoscopic procedures at three Canadian centres. Procedures were conducted under conscious sedation, which leaves the patient relaxed and comfortable but partially conscious during the procedure.
Cannabis use was associated with increased odds of requiring higher total sedation during gastroscopy, an endoscopic procedure that begins with the insertion of a tube and camera through the throat.
Legalisation not associated with increased cannabis use among young people
A recent study from researchers in Uruguay found that the use of cannabis following legalisation decreased among teenagers.
Uruguay was the first country in the world to legalise and regulate recreational cannabis. Since legalising the drug in 2016, the country is now regarded as a pioneer, paving the way for other countries like Canada, Mexico and Malta.
Using data from cross-sectional surveys of secondary students in Uruguay and Chile, the study evaluated changes in the prevalence of past-year, past-month and any risky and frequent cannabis use following the enactment and implementation of cannabis legalisation
“The legalisation of recreational cannabis in Uruguay was not associated with overall increases in either past-year/past-month cannabis use or with multi-year changes in any risky and frequent cannabis use among young people,” the authors stated in the paper’s abstract.
Current cannabis labelling system “doesn’t tell you much”
Labels like indica, sativa and hybrid—commonly used to distinguish one category of cannabis from another—tell consumers little about what’s in their product and could be confusing or misleading, suggests a new study of nearly 90,000 samples across six states in America.
Published on 19 May in the journal PLOS One, the research constitutes the largest analysis to date of the chemical composition of cannabis products.
It finds that commercial labels “do not consistently align with the observed chemical diversity” of the product. The authors are now calling for a “weed labelling system” akin to the Food and Drug Administration’s “nutrition facts panel” for food.
“Our findings suggest that the prevailing labelling system is not an effective or safe way to provide information about these products,” said co-author Brian Keegan, an assistant professor of Information Science at CU Boulder.
“This is a real challenge for an industry that is trying to professionalise itself.”
Cannabis dependence treatment is effective in tackling common co-morbidities
Earlier this month, Australian researchers released a paper looking into the effectiveness of cannabis dependency treatment on common co-morbidities, including mood, sleep and pain problems.
The researchers found that the treatment helped decrease anxiety, stress and sleep disturbance among the cohort of 128 cannabis-dependent participants.
The analysis used data from a 12-week double-blind placebo-controlled trial testing the effectiveness of the cannabis-based medicine nabiximols against placebo in reducing illicit cannabis use.
The researchers found that there was “no evidence” that nabiximols treatment is a barrier to reducing co-morbid symptoms. In fact, they found that the treatment reduced illicit cannabis use and improved comorbidity symptoms, even when participants were not able to achieve abstinence.
Research finds cannabis consumers may require more sedation
Consumers required higher levels of sedation during endoscopic procedures than non-users
Experts have highlighted the need for doctors to be more aware of their patients cannabis use, as research suggests consumers may require higher levels of sedation.
As cannabis is legalised in more places and usage continues to rise, researchers in Canada said clinicians should be aware of patients’ cannabis consumption, and prepare themselves for increased sedation and the risks that come with it.
It comes as a new study has associated cannabinoid use with increased odds of requiring higher total sedation during gastric endoscopies – a procedure that begins with the insertion of a tube and camera through the throat – than non-users.
The authors of the study conducted a prospective cohort study of 419 adult outpatients undergoing endoscopic procedures at three Canadian centres.
Procedures were conducted under conscious sedation, which leaves the patient relaxed and comfortable but partially conscious during the procedure.
“Patients didn’t have increased awareness or discomfort during procedures, but they did require more drugs,” said Yasmin Nasser, MD, PhD, lead researcher on the study and assistant professor at Snyder Institute for Chronic Diseases at the University of Calgary.
Each patient completed two questionnaires, one before the procedure about their cannabis use and another afterwards, indicating their awareness and comfort level during the procedure. The questionnaires were analysed along with details about the use of the sedatives midazolam, fentanyl and diphenhydramine during the procedure.
Cannabis use was associated with increased odds of requiring higher total sedation—defined as more than 5 mg of midazolam, or more than 100 mcg of fentanyl, or the need for diphenhydramine.
Interestingly, cannabis use was not associated with higher use of sedation during colonoscopy. Researchers said this could be because gastroscopy generally requires more sedation than colonoscopy due to the irritation caused in the upper part of the gastrointestinal tract.
Cannabinoid use was not independently associated with fentanyl use or adverse events, nor was it associated with intra-procedural awareness or discomfort, the authors found.
This study looked at whether patients were users or non-users of cannabis, but did not examine the timing, quantity or route of cannabis intake prior to the procedure. Researchers say these variables could be the basis for future studies.
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