Regular marijuana users don't have an increased risk of cancer compared to people who only toke every now and then.
That's the findings of a report submitted at the annual American Association of Cancer Research this week that includes data from six case-controlled studies between 1999 and 2012.
Dr. Li Rita Zhang from the University of California, Los Angeles, looked at 2,159 lung cancer cases and compared them to 2,985 people without lung cancer. All of the participants took part in International Lung Cancer Consortium studies in the U.S., Canada, the United Kingdom and New Zealand.
Zhang took into account people who also smoked tobacco, separating them from people who only smoked cannabis. That left her with 370 lung cancer patients and about 1,358 patients from the control group. She studied both groups and came up with two major findings: habitual pot smokers didn't have an increased risk compared to their tobacco-smoking counterparts and when compared to non-smokers, there were no major differences to be found. Some of the subjects were daily smokers of three or more joints and had been for as long as 20 years.
But don't think Zhang is in favor of cannabis smoking. She declined to comment further on her study to Clinical Psychiatry News, but said the following in the study: "Our results cannot preclude the possibility that cannabis may exhibit an association with lung cancer risk at extremely high dosage over long periods of continued exposure."