use linked to early bladder cancer
Source: January Issue Of Urology
Toni Baker Jan. 26, 2006
Smoking marijuana appears to be a risk factor for bladder
cancer and may even contribute to younger people getting the
disease, researchers say.
Smoking cigarettes is the major risk factor for bladder
cancer, which is most common among people age 60 and older,
says Dr. Martha Terris, urologist at the Medical College of
Georgia and Veterans Affairs Medical Center in Augusta.
But a study of younger patients * 52 men age 44 to 60
* with transitional cell bladder cancer at VA hospitals in
Augusta and Palo Alto, Calif., showed that 88.5 percent had
a history of smoking marijuana, says Dr. Terris, senior
author on the study published in the January issue of
Nearly 31 percent of the cancer patients still smoked
marijuana, compared to 20 percent of those in an age-matched
"We noticed several younger patients who had developed
transitional cell carcinoma were similar in that they all
shared a history of marijuana smoking," Dr. Terris says.
"The literature has suggesed that marijuana-smoking
increases the risk of head and neck cancer and lung
malignancies, and that these tumors tend to develop earlier
and behave more aggressively in marijuana smokers."
That prompted physicians at the VA hospitals affiliated with
Stanford University Medical Center and MCG to look at
marijuana use as well as exposure to other carcinogens,
including tobacco, radiation, Agent Orange, smoked or
processed meats and synthetic dyes used in the textile
industry, in their patients. Serving as controls were 104
patients seeking urology care at the VA hospitals for
reasons other than bladder cancer.
Bladder cancer patients and controls had similar rates of
exposure to all the risk factors except marijuana. In fact,
the study indicates smoking marijuana may be as bad or worse
than cigarette smoking as a risk factor for bladder cancer.
"Marijuana-smoking might be an even more potent stimulant of
malignant transformation in transitional epithelium than
tobacco smoking," they write, noting that marijuana
metabolites have a half-life in the urine about five times
greater than nicotine metabolites. Studies of
delta-9-tetrahydrocannabinol, or THC, the main psychoactive
substance in marijuana, have demonstrated both anti-tumor
and tumor-promoting properties. Either way, THC hangs around
a long time in the bladder and urine.
Marijuana smoke also has many of the same
carcinogen-containing tars as cigarettes and may get even
more into the body because marijuana cigarettes are
unfiltered and users tend to hold the smoke in their lungs
for prolonged periods, researchers say.
The combination of smoking cigarettes and marijuana may have
an unfortunate synergy. "The differences and interactions
between marijuana and tobacco use also merit further
scrutiny," they write.
Also, larger-scale epidemiologic and basic science studies
are needed to confirm the role of marijuana use in
development of bladder cancer.
For now, when doctors find blood in a young patient's urine
sample, they may want to include questions about marijuana
use in their follow-up and more strongly consider bladder
cancer as a cause, says Dr. Terris.
And, bladder cancer patients considering marijuana to treat
chemotherapy side effects, may want to reconsider. "If they
are getting chemotherapy for their bladder cancer and
smoking marijuana to increase their appetite, they may be
undoing the benefits of chemotherapy," she says.
She noted it is likely that, as with cigarettes, risks of
marijuana-smoking diminish after patients stop but never go
away. "The safest move is to never start smoking anything,"