STUDY: SMOKING MARIJUANA DOES NOT CAUSE LUNG CANCER
- From: "name" <dohduhdah@xxxxxxxxx>
- Date: 8 Jul 2005 19:33:54 -0700
STUDY: SMOKING MARIJUANA DOES NOT CAUSE LUNG CANCER
http://www.mapinc.org/norml/v05/n1065/a03.htm?134
02 Jul 2005
by Fred Gardner, (Source:CounterPunch)
United States
-------
Marijuana smoking -"even heavy longterm use"- does not cause cancer of
the lung, upper airwaves, or esophagus, Donald Tashkin reported at this
year's meeting of the International Cannabinoid Research Society.
Coming from Tashkin, this conclusion had extra significance for the
assembled drug-company and university-based scientists ( most of whom
get funding from the U.S. National Institute on Drug Abuse ). Over
the
years, Tashkin's lab at UCLA has produced irrefutable evidence of the
damage that marijuana smoke wreaks on bronchial tissue. With NIDA's
support, Tashkin and colleagues have identified the potent carcinogens
in marijuana smoke, biopsied and made photomicrographs of pre-malignant
cells, and studied the molecular changes occurring within them. It is
Tashkin's research that the Drug Czar's office cites in ads linking
marijuana to lung cancer. Tashkin himself has long believed in a
causal
relationship, despite a study in which Stephen Sidney examined the
files
of 64,000 Kaiser patients and found that marijuana users didn't develop
lung cancer at a higher rate or die earlier than non-users. Of five
smaller studies on the question, only two -involving a total of about
300 patients- concluded that marijuana smoking causes lung cancer.
Tashkin decided to settle the question by conducting a large,
prospectively designed, population-based, case-controlled study. "Our
major hypothesis," he told the ICRS, "was that heavy, longterm use of
marijuana will increase the risk of lung and upper-airwaves cancers."
The Los Angeles County Cancer Surveillance program provided Tashkin's
team with the names of 1,209 L.A. residents aged 59 or younger with
cancer ( 611 lung, 403 oral/pharyngeal, 90 laryngeal, 108 esophageal ).
Interviewers collected extensive lifetime histories of marijuana,
tobacco, alcohol and other drug use, and data on diet, occupational
exposures, family history of cancer, and various "socio-demographic
factors." Exposure to marijuana was measured in joint years ( joints
per
day x 365 ). Controls were found based on age, gender and
neighborhood.
Among them, 46% had never used marijuana, 31% had used less than one
joint year, 12% had used 10-30 j-yrs, 2% had used 30-60 j-yrs, and 3%
had used for more than 60 j-yrs. Tashkin controlled for tobacco use
and
calculated the relative risk of marijuana use resulting in lung and
upper airwaves cancers. All the odds ratios turned out to be less than
one ( one being equal to the control group's chances )! Compared with
subjects who had used less than one joint year, the estimated odds
ratios for lung cancer were .78; for 1-10 j-yrs, .74; for 10-30 j-yrs,
..85 for 30-60 j-yrs; and 0.81 for more than 60 j-yrs. The estimated
odds ratios for oral/pharyngeal cancers were 0.92 for 1-10 j-yrs; 0.89
for 10-30 j-yrs; 0.81 for 30-60 j-yrs; and 1.0 for more than 60 j-yrs.
"Similar, though less precise results were obtained for the other
cancer
sites," Tashkin reported. "We found absolutely no suggestion of a dose
response." The data on tobacco use, as expected, revealed "a very
potent
effect and a clear dose-response relationship -a 21-fold greater risk
of
developing lung cancer if you smoke more than two packs a day."
Similarly high odds obtained for oral/pharyngeal cancer, laryngeal
cancer and esophageal cancer. "So, in summary" Tashkin concluded, "we
failed to observe a positive association of marijuana use and other
potential confounders."
There was time for only one question, said the moderator, and San
Francisco oncologist Donald Abrams, M.D., was already at the
microphone:
"You don't see any positive correlation, but in at least one category
[marijuana-only smokers and lung cancer], it almost looked like there
was a negative correlation, i.e., a protective effect. Could you
comment on that?"
"Yes," said Tashkin. "The odds ratios are less than one almost
consistently, and in one category that relationship was significant,
but
I think that it would be difficult to extract from these data the
conclusion that marijuana is protective against lung cancer. But that
is not an unreasonable hypothesis."
Abrams had results of his own to report at the ICRS meeting. He and
his
colleagues at San Francisco General Hospital had conducted a
randomized,
placebo-controlled study involving 50 patients with HIV-related
peripheral neuropathy. Over the course of five days, patients recorded
their pain levels in a diary after smoking either NIDA-supplied
marijuana cigarettes or cigarettes from which the THC had been
extracted. About 25% didn't know or guessed wrong as to whether they
were smoking the placebos, which suggests that the blinding worked.
Abrams requested that his results not be described in detail prior to
publication in a peer-reviewed medical journal, but we can generalize:
they exceeded expectations, and show marijuana providing pain relief
comparable to Gabapentin, the most widely used treatment for a
condition
that afflicts some 30% of patients with HIV.
To a questioner who bemoaned the difficulty of "separating the high
from
the clinical benefits," Abrams replied: "I'm an oncologist as well as
an
AIDS doctor and I don't think that a drug that creates euphoria in
patients with terminal diseases is having an adverse effect." His study
was funded by the University of California's Center for Medicinal
Cannabis Research.
.
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