(DIR) Home
Could cannabis treat cancer someday? Here's what the science says so
far
(HTM) Source
----------------------------------------------------------------------
Research into the potential medical benefits of cannabis has exploded
in recent years, raising one intriguing question: Could cannabis treat
cancer?
It may sound far-fetched that weed — the high-inducing plant that
propagandists once warned would cause " _reefer madness_ " — could
contain ingredients that shrink tumors. However, experts told Live
Science that there is some early evidence that some cannabinoids, the
active ingredients found in cannabis, do have anticancer effects.
"There's no two ways about it: [Cannabis] has anticancer properties,"
_Wai Liu_ , a senior research fellow at St George's, University of
London, told Live Science. "But the problem is, how do you translate
that into the clinic — and that's the difficult question to address."
Here's what we know so far about Mary Jane's cancer-fighting powers.
**Related:** _ **Runners enjoyed their workouts more after using
cannabis, but physically floundered**_
## What are cannabinoids, and can they treat cancer?
The cannabis plant comes in _more than 700 varieties_ , with famous
examples including _Cannabis sativa_ and _Cannabis indica_. Cannabis
plants contain substances called cannabinoids, or chemicals that
interact with the endocannabinoid system in the _brain_.
Endocannabinoids made by the body help regulate a plethora of
_biological functions_ , including eating, learning and _pain
recognition_.
Plant-made cannabinoids, of which more than 100 have been identified
by scientists, plug into this same system and affect its activity.
These plant-made molecules include tetrahydrocannabinol (THC), which
is largely responsible for the _characteristic "high"_ associated with
cannabis, and cannabidiol (CBD), which doesn't produce a high but has
been studied for its _potential medicinal effects_.
Get the world's most fascinating discoveries delivered straight to
your inbox.
These and other cannabinoids can now be made synthetically in the lab,
as well. In fact, two drugs that contain synthetic THC — _dronabinol
and nabilone_ — are already approved by the U.S. Food and Drug
Administration to treat the nausea and vomiting triggered by
chemotherapy.
However, research studying whether cannabinoids directly shrink tumors
is in its very early days. At this point, it's been mainly limited to
_preclinical studies_ in human or mouse cells in lab dishes and in
animals such as mice. For instance, synthetic and plant-made
cannabinoids have been shown to impede the growth of _breast cancer_
in mice; in these experiments, cannabinoids were injected into the
area directly around the tumor, as well as _colorectal cancer_ ,
_prostate cancer_ and _skin cancer_ in cells.
There are _several ways_ in which cannabinoids have been shown to have
anticancer properties, Liu said. For example, in rodent studies,
cannabinoids have been shown to _inhibit cancer cell growth_ by
flipping specific molecular switches in tumor cells. And in cell
studies, cannabinoids have damaged tumors by flooding them with
harmful molecules called _reactive oxygen species_ , he said.
However, it's not all positive — under certain circumstances, THC has
been shown to _promote tumor growth_ in animal models. These
differences could partly be explained by studies using varying doses
and investigating distinct types of cancer, the authors suggested.
**Related:** _ **Cannabis poisonings in young kids skyrocketed
following legalization of edibles**_
Despite significant scientific interest, no cannabis-related compound
has been shown to treat cancer in humans. (Image credit: janiecbros
via Getty Images)
## Have any cannabinoid-based cancer treatments been tested in humans?
For any cannabinoid-based cancer treatments to reach the market,
they'd need to be tested in humans.
"There's a big difference between what you observe in a cell line in a
petri dish compared to what will happen if you treat a human who has
that cancer," _Dr. Mikael Sodergren_ , head of the Medical Cannabis
Research Group at Imperial College London, told Live Science.
However, so far, there have been only a few small clinical trials, and
all have focused on just one type of cancer: _glioblastoma_ , the most
aggressive form of brain cancer. Current treatments for glioblastoma
have poor survival rates meaning that _new approaches are urgently
needed_.
In the first trial, conducted in 2006, scientists showed that THC
injections directly into the tumors of patients with brain cancer
could safely and effectively _inhibit their growth_. The trial
included just nine patients with glioblastoma. So, although these
results were encouraging, the sample size of the study was too small
to make any firm conclusions about the drug's safety and efficacy.
In 2021, a separate research group _published the results_ of another
early clinical trial, which included 27 people. One group of
participants used a mouth spray containing a mixture of CBD and THC in
combination with a traditional chemotherapy drug called temozolomide.
They received between 3-12 sprays a day (up to 30 milligrams of CBD
and 32.4 mg of THC), depending on their maximum tolerated dose. All of
the patients had glioblastoma that had returned following standard,
first-line therapy.
This trial included a comparison group that did not use the
cannabinoid spray, and by comparison, almost twice as many patients
who received the spray were alive after one year.
It's still unknown how the spray may affect tumor growth, but it's
possible that these compounds help push brain tumor cells toward cell
death, thereby enhancing the antitumor activity of temozolomide, _Dr.
Susan Short_ , a professor of clinical oncology at the University of
Leeds in the U.K. who led the research, told Live Science.
The centres that are running the study are now aiming to recruit
around 240 patients into a larger, midstage clinical trial. They hope
to be able to share the results of that trial within two years from
now, Short said.
Clinical research has focused on the most aggressive form of brain
cancer, glioblastoma, shown in high detail under the microscope above.
(Image credit: Nephron, CC BY-SA 3.0 DEED, via Wikimedia Commons
https://creativecommons.org/licenses/by-sa/3.0/deed.en)
## What's still unknown?
Despite this progress, _many questions remain_ about how cannabinoids
might fight cancer at the molecular level, as well as which dosage and
administration route would work best in humans.
And, if approved as a cancer treatment, THC would likely have to be
_combined with another form of cancer therapy_ , because only low
doses could be given to patients to avoid inducing a high, he said. In
clinical trials, it would also be unethical to exclude proven
treatment methods from patients, so testing the effects of cannabinoid
treatment by itself could be tricky.
In the meantime, the positive signals scientists have seen in cellular
models are certainly worth investigating further, _Dr. Brooke Worster_
, an assistant professor of medicine at Thomas Jefferson University in
Pennsylvania, told Live Science. Such studies could help clarify how
cannabinoids affect cancer cells and which are most promising as
treatments.
In the meantime, though, patients should take the results of these
studies with a grain of salt, she said. No one should use the early
data about cannabinoids to avoid taking treatments that are already
known to be effective against cancer, such as _immunotherapy_ and
_radiation therapy_ , she said.
There's a _misconception that "natural"_ treatments _are always
better_ for you. But given that there isn't gold-standard proof that
cannabinoids can treat cancer, opting for weed over chemo wouldn't be
advisable, Worster added.
_This article is for informational purposes only and is not meant to
offer medical advice._
_Ever wonder why_ _ _some people build muscle more easily than
others__ _or_ _ _why freckles come out in the sun__ _? Send us your
questions about how the human body works to_ _
_community@livescience.com__ _with the subject line "Health Desk Q,"
and you may see your question answered on the website!_
______________________________________________________________________
Served by Flask-Gopher/2.2.1