Featured Research

from universities, journals, and other organizations

Study Finds No Link Between Marijuana Use And Lung Cancer

Date:
May 26, 2006
Source:
American Thoracic Society
Summary:
People who smoke marijuana -- even heavy, long-term marijuana users -- do not appear to be at increased risk for developing lung cancer, according to a study to be presented at the American Thoracic Society International Conference on May 23.

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.

Related Articles


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.


Story Source:

The above story is based on materials provided by American Thoracic Society. Note: Materials may be edited for content and length.


Cite This Page:

American Thoracic Society. "Study Finds No Link Between Marijuana Use And Lung Cancer." ScienceDaily. ScienceDaily, 26 May 2006. <www.sciencedaily.com/releases/2006/05/060526083353.htm>.
American Thoracic Society. (2006, May 26). Study Finds No Link Between Marijuana Use And Lung Cancer. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2006/05/060526083353.htm
American Thoracic Society. "Study Finds No Link Between Marijuana Use And Lung Cancer." ScienceDaily. www.sciencedaily.com/releases/2006/05/060526083353.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Earthworms Provide Cancer-Fighting Bacteria

Earthworms Provide Cancer-Fighting Bacteria

Reuters - Innovations Video Online (Dec. 21, 2014) Polish scientists isolate bacteria from earthworm intestines which they say may be used in antibiotics and cancer treatments. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Existing Chemical Compounds Could Revive Failing Antibiotics, Says Danish Scientist

Existing Chemical Compounds Could Revive Failing Antibiotics, Says Danish Scientist

Reuters - Innovations Video Online (Dec. 21, 2014) A team of scientists led by Danish chemist Jorn Christensen says they have isolated two chemical compounds within an existing antipsychotic medication that could be used to help a range of failing antibiotics work against killer bacterial infections, such as Tuberculosis. Jim Drury went to meet him. Video provided by Reuters
Powered by NewsLook.com
Hugging It Out Could Help You Ward Off A Cold

Hugging It Out Could Help You Ward Off A Cold

Newsy (Dec. 21, 2014) Carnegie Mellon researchers found frequent hugs can help people avoid stress-related illnesses. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins