Pubdate: Mon, 23 Oct 2017
Source: Globe and Mail (Canada)
Copyright: 2017 The Globe and Mail Company
Author: Adriana Barton
Page: L1


With legalization on the horizon in Canada, dispensaries are marketing
marijuana as a cure for what ails you - including cancer. Do the
claims hold up? Adriana Barton takes a closer look at the science
behind cancer and cannabis

In a lab at the University of Nottingham in England, brain-cancer
specialist Richard Grundy is growing cells from children's brain
tumours to see if cannabidiol - a compound in marijuana - can kill

Brain-tumour cells rarely thrive outside the body, though, so he'll be
lucky if half a dozen cell clusters survive long enough to study the
hunch. Even if the compound snuffs out cancer cells in the lab,
there's no guarantee it would do the same in humans. "But," he said,
"one has to start somewhere."

That sums up the current stage of research on cannabis and cancer -
it's at the start. Compelling stories of patient recoveries, combined
with laboratory evidence of possible cancer-fighting effects, have
spurred researchers worldwide to put cannabis to the test. So far,
scientists have observed anti-tumour activity in cells cultured in
Petri dishes or grafted onto mice. But mice and people are different
beasts. Plenty of experimental cancer therapies have shown promise in
early studies - such as dichloroacetic acid (DCA) - only to fail in
human trials.

But the cautious pace of medical research hasn't stopped Canada's
unregulated marijuana dispensaries from marketing cannabis as a cancer
cure. Some sell it with a veneer of science, quoting Harvard
University researchers out of context as saying cannabis
"significantly reduces the ability of the cancer to spread." Others
link to a video with 1.2-million YouTube views featuring Rick Simpson,
a Canadian living abroad who claims homegrown cannabis oil cured his
skin cancer. Several websites take a conspiracy theory approach,
describing a high potency cannabis oil called "Phoenix Tears" as "the
cancer cure the government doesn't want you to know about."

As Canada hurtles toward new legislation to legalize marijuana in
2018, the buzz has left many Canadians wondering whether medical
cannabis can help them recover from cancer. "It's a very common
question we do get," said Robert Nuttall, assistant director of health
policy at the Canadian Cancer Society, which outlines the facts about
cannabis and cancer on its website.

No one can blame a cancer patient for wanting to try anything possible
to get well - or at least take the edge off chemotherapy-induced
nausea and other nasty side effects.

But when it comes to treatment, scientists have yet to determine
whether marijuana's unproven anti-tumour properties outweigh the
potential harms of consuming high-potency cannabis oils and extracts.
To make sense of the evolving science, The Globe and Mail combed
through the evidence and spoke to authorities in medical marijuana
research. Here's our take on some questions about cannabis in cancer

What are cannabinoids? How can they help cancer patients?

Cannabinoids are the compounds in marijuana that have drug-like
effects. THC, short for tetrahydrocannabinol, can dull pain and make
people "high," while cannabidiol (CBD) may lower pain without
psychoactive effects. These and other compounds in marijuana bind to
receptors on cells throughout the body, including the brain, immune
system and central nervous system, instructing cells to perform
specific functions. In cancer patients, some of these instructions may
help relieve chemotherapy side effects such as nausea, vomiting and
appetite loss.

Do cancer patients have to smoke marijuana to get the

No. In fact, inhaled cannabis has shown mixed results in studies of
chemotherapy-induced nausea and vomiting. Instead, a doctor may
prescribe an edible oil containing THC and CBD from a licensed medical
cannabis producer, or a synthetic cannabinoid such as nabilone, an
anti-nausea drug that mimics THC.

Before using cannabis in any form, Nuttall said, patients should
discuss it with a medical doctor or oncologist to avoid side effects
or possible drug interactions with their cancer treatments.

What are the upsides of medical cannabis for cancer

Certain pharmaceutical drugs may be more effective in treating
individual symptoms, such as chemotherapy-related nausea. But when
doctors prescribe a different drug for each side effect, the pill
count adds up, said Vincent Maida, a palliative medicine specialist at
the University of Toronto and co-author of a 2016 guide to cannabinoid
therapies in oncology published in the Canadian journal, Current
Oncology. Since medical cannabis can relieve multiple symptoms, "we're
able to help the pain, the nausea and the anorexia [appetite loss]."

Cannabinoids may also reduce dependence on opioid painkillers, said
Maida, whose research is not funded by the medical cannabis industry
(although he does accept occasional speaker's fees). Maida cites data
showing that cancer patients on high-dose opioids are at greater risk
for metastases (cancer spread), infections (opioids suppress the
immune system) and opioid addiction. Expanding the use of cannabinoid
therapies "can be regarded as an overall risk-reduction strategy."

What about a cure? Doesn't cannabis kill cancer cells?

Certain chemicals derived from cannabis may kill tumour cells in a
Petri dish, but so does bleach. That doesn't make bleach a cancer
treatment. Testing compounds in Petri dishes, known as in vitro
research, helps researchers gauge whether a substance shows enough
effects to justify animal testing. But both in vitro and animal
studies represent the earliest stages of medical research.

So far, the only published human trial of cannabinoids for tumours
involved nine patients with terminal brain cancer. In this 2006 study,
Spanish researchers injected medical-grade THC through a catheter in
patients' brains, "which is different from people smoking a joint,"
Nuttall said. The researchers found signs of reduced tumour growth in
cells taken from two patients, but all nine patients died from their
tumours within months.

The authors emphasized they could draw no conclusions about THC's
cancer-fighting potential based on the pilot study. There's a chance,
in fact, that cannabis may have the opposite effect. In one in vitro
study, published in 2010, researchers found that cannabinoids, under
certain conditions, could interfere with the immune system's
tumour-suppressing role. In a 2004 study and a 2005 study,
cannabinoids appeared to stimulate cancer-cell growth.

It will take scientists years to figure how different types of cancer
respond to specific compounds in marijuana, said Rukiyah Van
DrossAnderson, an associate professor of pharmacology and toxicology
at East Carolina University. In 2016, she co-authored a review of
dozens of studies looking at the effects of cannabinoids on cancers of
the brain, digestive system, breast cancer, prostate, lungs, thyroid
and skin. In a phone interview, she described the research as
"promising," but added that so far "there is not enough evidence for
any of the cancers to state confidently that it is effective and safe."

What about cancer patients who have gone into remission after using

These are anecdotes, not evidence. In California, a cannabis company
called Aunt Zelda's is building a database of reports from patients
who say cannabis therapies helped them recover from cancer. But
without rigorous medical documentation, no one knows whether the
patient got better because of the cannabis, previous radiation and
chemotherapy, or some other factor in the patient's life.

Rick Simpson of "marijuana miracle" fame may have bounced back from
skin cancer, but a single remission hardly makes cannabis a
one-size-fits-all treatment for the many different diseases we call
cancer. Even the most promising findings suggest cannabinoids may
shrink tumours, not eliminate them, Maida said. Hypothetically, if
patients were suddenly free of cancer, "I would suspect that they were
spontaneous remissions," he said. "And not an absolute cure induced by

I have late-stage cancer. What have I got to lose?

For patients in end-of-life care, medical cannabis may reduce pain,
help with sleep and improve mood. But as a "Hail Mary" treatment for
terminal cancer, unregulated cannabis products can backfire. Marijuana
dispensaries typically recommend extremely high doses of concentrated
THC and/or CBD for cancer patients. These high-potency oils have no
proven benefits over licensed medical marijuana - and may decrease
quality of life, Maida said. At these levels, "you're going to make
[patients] completely psychotic and sedated."

Do-it-yourself cancer therapy using products such as "Rick Simpson
oil" or Phoenix Tears - sold as high-potency "cure-alls" through
dozens of Canadian dispensaries - can easily cost more than $1,000 a
month. But the biggest risk, particularly for patients with vulnerable
immune systems, may be infection from bacterial or fungal
contamination, or exposure to carcinogenic pesticides, Van
Dross-Anderson said. Using a regulated product is the only way to
ensure contaminants are removed. "I can understand people's
desperation," she said, but instead of taking a chance on dispensary
products, "it would be better to enroll in a clinical trial."

So what's the good news?

As marijuana loses it reefer-madness stigma, researchers are having an
easier time securing funding and regulatory approval for research on
cannabinoids, said Van DrossAnderson, whose lab is studying the
effects of a cannabinoid derivative on melanoma skin-cancer cells.

At the University of Canberra in Australia, researchers have gathered
funding to conduct a human trial of cannabis therapy on patients with
melanoma skin cancer, providing they produce safety data from animal
trials and obtain ethical and regulatory approval. In Britain, GW
Pharmaceuticals has completed a phase-two trial of synthetic cannabis
compounds, combined with chemotherapy, in patients with glioma, an
aggressive type of brain tumour. The company released initial findings
in February, but the results have not been peer-reviewed or published
in a medical journal.

Van Dross-Anderson speculates that cannabinoid treatments for glioma
brain cancers - the most widely studied to date - may not be far off:
"We could be looking at 10 years."

Grundy is more circumspect, but emphasizes the urgent need for more
research. Parents of children with brain tumours often feel pressure
from friends and family to give cannabis products a try, "even though
there's no real evidence for it," he said. "I think it's a question
that needs answers."
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MAP posted-by: Matt