Study finds no marijuana link to lung cancer

[BlueMystic]

http://news.yahoo.com/s/nm/20060524/...NlYwNtZW5ld3M-

LOS ANGELES (Reuters) - Marijuana smoking does not increase a person's risk of developing lung cancer, according to the findings of a new study at the University of California Los Angeles that surprised even the researchers.

They had expected to find that a history of heavy marijuana use, like cigarette smoking, would increase the risk of cancer.

Instead, the study, which compared the lifestyles of 611 Los Angeles County lung cancer patients and 601 patients with head and neck cancers with those of 1,040 people without cancer, found no elevated cancer risk for even the heaviest pot smokers. It did find a 20-fold increased risk of lung cancer in people who smoked two or more packs of cigarettes a day.

The study results were presented in San Diego on Tuesday at a meeting of the American Thoracic Society.

The study was confined to people under age 60 since baby boomers were the most likely age group to have long-term exposure to marijuana, said Dr. Donald Tashkin, senior researcher and professor at the UCLA School of Medicine.

The results should not be taken as a blank check to smoke pot, which has been associated with problems like cognitive impairment and chronic bronchitis, said Dr. John Hansen-Flaschen, chief of pulmonary and critical care at the University of Pennsylvania Health System in Philadelphia. He was not involved in the study.

Previous studies showed marijuana tar contained about 50 percent more of the chemicals linked to lung cancer, compared with tobacco tar, Tashkin said. In addition, smoking a marijuana joint deposits four times more tar in the lungs than smoking an equivalent amount of tobacco.

"Marijuana is packed more loosely than tobacco, so there's less filtration through the rod of the cigarette, so more particles will be inhaled," Tashkin said in a statement. "And marijuana smokers typically smoke differently than tobacco smokers -- they hold their breath about four times longer, allowing more time for extra fine particles to deposit in the lung."

He theorized that tetrahydrocannabinol, or THC, a chemical in marijuana smoke that produces its psychotropic effect, may encourage aging, damaged cells to die off before they become cancerous.

Hansen-Flaschen also cautioned a cancer-marijuana link could emerge as baby boomers age and there may be smaller population groups, based on genetics or other factors, still at risk for marijuana-related cancers.

[Urban]

Even Smoking 22,000 Joints Will Not Give You Cancer


A team of UCLA researches recently published the results of their study on the possible link between heavy marijuana use and cancer. Guess what? There is none! That's right - the researchers found no increased incidence of cancer among the over 2,200 people they observed, some of whom had consumed over 22,000 joints in their lifetime (!!). Marijuana expert and good friend, Mitch Earleywine, brought this study to my attention. His comments in an email this morning were spot on:


This is a fine study conducted by a recognized expert in the field. The sample is extremely large, and the design is powerful. Clearly, if marijuana caused lung cancer, it should appear in this study. The compelling evidence for tobacco-induced lung cancer suggests that the study is perfectly capable of revealing correlates of this disease. Surely now we can all see that the most negative consequences of cannabis are legal!
Apparently, the researchers themselves were shocked [shocked I tell you] by the results. Can't you just imagine them going over the data again and again to be sure they hadn't made some mistake:


The new findings are surprising for several reasons, Dr. Tashkin said. Previous studies have shown that marijuana tar contains about 50% higher concentrations of chemicals linked to lung cancer, compared with tobacco tar, he noted. Smoking a marijuana cigarette deposits four times more tar in the lungs than smoking an equivalent amount of tobacco. "Marijuana is packed more loosely than tobacco, so there’s less filtration through the rod of the cigarette, so more particles will be inhaled," Dr. Tashkin said. "And marijuana smokers typically smoke differently than tobacco smokers - they hold their breath about four times longer, allowing more time for extra fine particles to deposit in the lung."

One possible explanation for the new findings, he said, is that THC, a chemical in marijuana smoke, may encourage aging cells to die earlier and therefore be less likely to undergo cancerous transformation.

The next step, Dr. Tashkin says, is to study the DNA samples of the subjects, to see whether there are some heavy marijuana users who may be at increased risk of developing cancer if they have a genetic susceptibility for cancer.

[Urban]

People who smoke marijuana—even heavy, long-term marijuana users—do not appear to be at increased risk of developing lung cancer, according to a study to be presented at the American Thoracic Society International Conference on May 23rd. Press Briefing at 10:15 a.m. (PDT).



Newswise — People who smoke marijuana—even heavy, long-term marijuana users—do not appear to be at increased risk of developing lung cancer, according to a study to be presented at the American Thoracic Society International Conference on May 23rd.

Marijuana smoking also did not appear to increase the risk of head and neck cancers, such as cancer of the tongue, mouth, throat, or esophagus, the study found.

The findings were a surprise to the researchers. “We expected that we would find that a history of heavy marijuana use—more than 500-1,000 uses—would increase the risk of cancer from several years to decades after exposure to marijuana,” said the senior researcher, Donald Tashkin, M.D., Professor of Medicine at the David Geffen School of Medicine at UCLA in Los Angeles.

The study looked at 611 people in Los Angeles County who developed lung cancer, 601 who developed cancer of the head or neck regions, and 1,040 people without cancer who were matched on age, gender and neighborhood. The researchers used the University of Southern California Tumor Registry, which is notified as soon as a patient in Los Angeles County receives a diagnosis of cancer.

They limited the study to people under age 60. “If you were born prior to 1940, you were unlikely to be exposed to marijuana use during your teens and 20s—the time of peak marijuana use,” Dr. Tashkin said. People who were exposed to marijuana use in their youth are just now getting to the age when cancer typically starts to develop, he added.

Subjects were asked about lifetime use of marijuana, tobacco and alcohol, as well as other drugs, their diet, occupation, family history of cancer and socioeconomic status. The subjects’ reported use of marijuana was similar to that found in other surveys, Dr. Tashkin noted.

The heaviest smokers in the study had smoked more than 22,000 marijuana cigarettes, or joints, while moderately heavy smokers had smoked between 11,000 to 22,000 joints. Even these smokers did not have an increased risk of developing cancer. People who smoked more marijuana were not at any increased risk compared with those who smoked less marijuana or none at all.

The study found that 80% of lung cancer patients and 70% of patients with head and neck cancer had smoked tobacco, while only about half of patients with both types of cancer smoked marijuana.

There was a clear association between smoking tobacco and cancer. The study found a 20-fold increased risk of lung cancer in people who smoked two or more packs of cigarettes a day. The more tobacco a person smoked, the greater the risk of developing both lung cancer and head and neck cancers, findings that were consistent with many previous studies.

The new findings are surprising for several reasons, Dr. Tashkin said. Previous studies have shown that marijuana tar contains about 50% higher concentrations of chemicals linked to lung cancer, compared with tobacco tar, he noted. Smoking a marijuana cigarette deposits four times more tar in the lungs than smoking an equivalent amount of tobacco. “Marijuana is packed more loosely than tobacco, so there’s less filtration through the rod of the cigarette, so more particles will be inhaled,” Dr. Tashkin said. “And marijuana smokers typically smoke differently than tobacco smokers—they hold their breath about four times longer, allowing more time for extra fine particles to deposit in the lung.”

One possible explanation for the new findings, he said, is that THC, a chemical in marijuana smoke, may encourage aging cells to die earlier and therefore be less likely to undergo cancerous transformation.

The next step, Dr. Tashkin says, is to study the DNA samples of the subjects, to see whether there are some heavy marijuana users who may be at increased risk of developing cancer if they have a genetic susceptibility for cancer.

[Mr. Giraffe]

Good stuff out of them.

Another study for the media to ignore, 'til some brainbox decides to compare tobacco-hash joints with filtered cigarettes again, and then we'll see the 'cannabis 2 million times more dangerous than tobacco' headlines again.

All of these scientific facts have been known for decades. It's just as well we're so infantile or all these scientists would be out of a job.