A team of Spanish researchers has discovered that
cannabinoids, the active ingredients in marijuana, make brain
tumors shrink by halting the growth of blood vessels that feed
the tumors, reports
New Scientist. The researchers have
successfully tested the effect of this cannabis extract on
thirty mice which were given a cancer similar to the human brain
cancer (glioblastoma multiforme). More importantly, they also
successfully tested the procedure on two human patients who had
glioblastoma multiforme and had not responded to chemotherapy,
radiotherapy or surgery. Of course, these results are
encouraging, even if larger studies need to be done to be sure
that these cannabinoids are really effective on human brain
cancers, and possibly other forms of cancers. Read more...
Here is the introduction of the New Scientist article.
Cannabis extracts may shrink brain tumours and other cancers
by blocking the growth of the blood vessels which feed them,
suggests a new study.
An active component of the street drug has previously been
shown to improve brain tumours in rats. But now Manuel
Guzmán at Complutense University, Spain, and colleagues have
demonstrated how the cannabis extracts block a key chemical
needed for tumours to sprout blood vessels -- a process
Will this turn on a new weapon against cancer?
Cristina Blázquez at Complutense University, and one of the
team, stresses the results are preliminary. "But it’s a good
point to start and continue."
"The cannabinoid inhibits the angiogenesis response - if a
tumour doesn’t do angiogenesis, it doesn’t grow," she
explains. "So if you can improve angiogenesis on one side
and kill the tumour cells on the other side, you can try for
a therapy for cancer."
What kind of tests were done?
The team tested the effects of delta-9-tetrahydrocannabinol
in 30 mice. They found the marijuana extract inhibited the
expression of several genes related to the production of a
chemical called vascular endothelial growth factor (VEGF).
VEGF is critical for angiogenesis, which allows tumours to
grow a network of blood vessels to supply their growth. The
cannabinoid significantly lowered the activity of VEGF in
the mice and two human brain cancer patients, the study
extract makes brain tumors shrink, halts growth of blood vessels,"
Medical News Today gives other details about the tests
done on human patients.
[The researchers] selected two patients who had glioblastoma
multiforme and had not responded to chemotherapy,
radiotherapy or surgery. The scientists took samples from
them before and after treating them with a cannabinoids
solution -- this was administered directly into the tumor.
Amazingly, both patients experienced reduced VEGF levels in
the tumor as a result of treatment with cannabinoids.
The researchers said that the results were encouraging. In
order to be sure about their findings they need to carry out
a larger study, they said.
||Here you can see the effect of the treatment on the
two patients with brain cancers. VEGFR-2 activation is
shown in green and its expression in red. Cell nuclei
are stained in blue. Relative values of
activated-VEGFR-2 pixels are displayed in parentheses
and total-VEGFR-2 pixels in square brackets are given
for the two patients per cell nucleus. (Credit:
For more information, you also can read this news release
from the American Association for Cancer Research, "Marijuana
ingredient inhibits VEGF pathway required for brain tumor blood
The research work has been published by the Cancer
Research journal under the title "Cannabinoids Inhibit the
Vascular Endothelial Growth Factor Pathway in Gliomas." Here are
two links to
the abstract and to the
full paper (PDF format, 7 pages, 732 KB).
The above illustration comes from this paper.
Sources: Shaoni Bhattacharya, New Scientist, August 15,
2004; Medical News Today, August 15, 2004; American Association
for Cancer Research news release, via EurekAlert!, August 15,
2004; Cancer Research, Vol. 64, Num. 16, Pages 5617-5623, August