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  • by Paul Armentano, NORML Deputy Director June 19, 2013

    A forthcoming review to be published in journal Annals of the American Thoracic Society reiterates that the ingestion of cannabis smoke poses nominal pulmonary risks compared to those associated with tobacco smoke. The author of the paper, Donald P. Tashkin, MD, emeritus professor of medicine and medical director of the Pulmonary Function Laboratory at the David Geffen School of Medicine at University of California, Los Angeles performed US-government sponsored studies of marijuana and lung function for over 30 years.

    A preview of Dr. Tashkin’s forthcoming review appears on the American Thoracic Society news website here. It reads:

    Dr. Tashkin found that regular smoking of marijuana by itself causes visible and microscopic injury to the large airways that is consistently associated with an increased likelihood of symptoms of chronic bronchitis that subside after cessation of use. He also found that the evidence does not indicate that habitual use of marijuana leads to significant abnormalities in lung function when assessed either cross-sectionally or longitudinally, except for possible increases in lung volumes and modest increases in airway resistance of unclear clinical significance.

    The author finds no clear link between marijuana use and the development of COPD or lower respiratory tract infections. In addition, “findings from a limited number of well-designed epidemiological studies do not suggest an increased risk for the development of either lung or upper airway cancer from light or moderate use, although evidence is mixed concerning possible carcinogenic risks of heavy, long-term use,” Dr. Tashkin notes. “In summary, the accumulated weight of evidence implies far lower risks for pulmonary complications of even regular heavy use of marijuana compared to the grave pulmonary consequences of tobacco.”

    The full paper will be available later this month.

    In May, presenters at the annual meeting of the American Academy for Cancer Research reported that subjects who regularly inhale cannabis smoke possess no greater risk of lung cancer than do those who consume it occasionally or not at all — according to an analysis of six case-control studies, conducted between 1999 and 2012, involving over 5,000 subjects (2,159 cases and 2,985 controls) from around the world.

    Last year, clinical data published in the Journal of the American Medical Association (JAMA) reported that subjects’ exposure to moderate levels of cannabis smoke, even over the long-term, is not associated with significant adverse effects on pulmonary function.

    Vaporizers, which heat marijuana to a point where cannabinoid vapors form, but below the point of combustion, reduce subjects’ intake of potentially hazardous combustible compounds. In several clinical trials, investigators have concluded that vaporization is a “safe and effective” cannabinoid delivery mode that “does not result in exposure to combustion gases.” Researchers also report that vaporization results in higher plasma concentrations of THC compared to smoked cannabis.

  • by Paul Armentano, NORML Deputy Director May 10, 2013

    In a recent presentation given at the annual meeting of the American Association of Cancer Research, investigators from the university of California, Los Angeles provided the latest data reaffirming that cannabis consumption is not associated with an elevated risk of lung cancer. Below is a summary of the findings from The Oncology Report:

    The study included data from six case-control studies conducted from 1999 to 2012 in the United States, Canada, the United Kingdom, and New Zealand, with a subject pool of 2,159 lung cancer cases and 2,985 controls. All of the studies were part of the International Lung Cancer Consortium (ILCCO), an international group of lung cancer researchers with the aim of sharing comparable data from ongoing and recently completed lung cancer studies from different geographical areas and ethnicities.

    Dr. Zhang of the University of California, Los Angeles, performed two analyses. One compared all lung cancer cases and all controls, regardless of concurrent or past tobacco use. Then, to reduce confounding by tobacco, she restricted the analysis to those who had never smoked tobacco.

    … When compared with cannabis smokers who also used tobacco, habitual pot smokers had no significant increase in cancer risk. In an analysis of marijuana smokers that excluded tobacco smokers, there were no significant differences in any of the comparisons, including habitual vs. nonhabitual use; number of joints smoked per day; duration of up to 20 years or duration of more than 20 years.

    The abstract of the presentation, which concludes “Our pooled results showed no significant association between the intensity, duration, or cumulative consumption of cannabis smoke and the risk of lung cancer overall or in never smokers,” is available online here.

    Numerous preclinical studies have documented that cannabinoids possess potent anti-cancer properties, including the inhibition of lung cancer cell growth.

  • by Paul Armentano, NORML Deputy Director February 1, 2012

    [Editor’s note: This post is excerpted from this week’s forthcoming NORML weekly media advisory. To have NORML’s news alerts and legislative advisories delivered straight to your in-box, sign up here.]

    Some two-thirds of Israeli cancer patients authorized to use cannabis report long-term, symptomatic improvement from the plant, according to clinical data presented in late January at a conference of the Israeli Oncologists Union and reported this week in several international media outlets.

    Investigators at the Sheba Medical Center in Tel Aviv, in conjunction with the Israeli Cancer Association, assessed the efficacy of cannabis therapy over the course of one year in 264 patients with cancer. Israeli media reported the findings:

    Some 61 percent of the respondents reported a significant improvement in their quality of life as a result of the medical marijuana, while 56 percent noted an improvement in their ability to manage pain. In general, 67 percent were in favor of the treatment, while 65 percent said they would recommend it to other patients.”

    The study concluded that cannabis is an “effective” treatment for certain symptoms of the disease cancer and recommended, “The treatment should be offered to the patients in earlier stages of cancer.”

    In the trial, the most common types of cancer for which medical marijuana was authorized was lung cancer (21 percent ), breast cancer (12 percent ) and pancreatic cancer (10 percent ).

    The study focused primarily on the use of cannabis to relieve various symptoms of cancer or cancer treatment, such as pain and nausea, but did not evaluate whether marijuana therapy could potentially suppress the proliferation of the disease. In preclinical trials, various cannabinoids – including THC and CBD (cannabidiol) – have been shown to selectively target and eliminate malignant cells and cancerous tumors.

    To date, some 6,000 Israelis possess government authorization to use cannabis therapeutically. Patients authorized by the federal program may either cultivate cannabis at home or they may obtain marijuana from one of the nation’s 12 licensed cannabis farms.

    Last summer, the Israeli Health Ministry formally acknowledged the therapeutic utility of cannabis and announced newly amended guidelines to more effectively govern the state-sponsored production and distribution of medical marijuana. The Ministry estimates that as many as 40,000 patients will eventually have access to medicinal cannabis once the Israeli program is fully implemented.

    NORML’s literature review of the anti-cancer properties of cannabis and cannabinoids is available here.

  • by Paul Armentano, NORML Deputy Director January 24, 2012

    The administration of the non-psychotropic cannabis plant constituent cannabidiol (CBD) is protective in an experimental model of colon cancer, according to preclinical trial data published online in the Journal of Molecular Medicine.

    Investigators at the University of Naples assessed the effect of CBD on colon carcinogenesis in mice. Researchers reported that CBD administration was associated with cancerous tumor reduction and reduced cell proliferation.

    Authors wrote: “Although cannabidiol has been shown to kill glioma cells, to inhibit cancer cell invasion and to reduce the growth of breast carcinoma and lung metastases in rodents, its effect on colon carcinogenesis has not been evaluated to date. This is an important omission, since colon cancer affects millions of individuals in Western countries. In the present study, we have shown that cannabidiol exerts (1) protective effects in an experimental model of colon cancer and (2) antiproliferative actions in colorectal carcinoma cells.”

    Authors also acknowledged that CBD possesses “an extremely safe profile in humans.” They concluded, “[O]ur findings suggest that cannabidiol might be worthy of clinical consideration in colon cancer prevention.”

    Clinical review data published in the scientific journal Current Drug Safety in December concluded that CBD is “non-toxic” to healthy cells and is “well tolerated” in humans. Nevertheless, cannabidiol is presently classified under federal law as a schedule I prohibited substance. Such substances are required by law to possess “a high potential for abuse,” “a lack of accepted safety … under medical supervision,” and “no currently accepted medical use in treatment in the United States.”

    Separate preclinical trials evaluating the anti-cancer activities of cannabinoids and endocannabinoids show that their administration can inhibit the proliferation of a variety of cancerous cell lines, including breast carcinoma, prostate carcinoma, gastric adenocarcinoma, skin carcinoma, leukemia cells, neuroblastoma, lung carcinoma, uterus carcinoma, thyroid epithelioma, pancreatic adenocarcinoma, cervical carcinoma, oral cancer, biliary tract cancer (cholangiocarcinoma), and lymphoma. NORML provides summaries and links to these studies here.

    Full text of this latest study, “Chemopreventive effect of the non-psychotropic phytocannabinoid cannabidiol on experimental colon cancer,” appears in the Journal of Molecular Medicine.

  • by Paul Armentano, NORML Deputy Director January 10, 2012

    Exposure to cannabis smoke, even over the long-term, is not associated with adverse effects on pulmonary function. That’s the conclusion of a major clinical trial published today in the prestigious Journal of the American Medical Association (JAMA).

    Investigators at the University of California, San Francisco analyzed the association between marijuana exposure and pulmonary function over a 20 year period in a cohort of 5,115 men and women in four US cities.

    Predictably, researchers “confirmed the expected reductions in FEV1 (forced expiratory volume in the first second of expiration) and FVC (forced vital capacity)” in tobacco smokers. By contrast, “Marijuana use was associated with higher FEV1 and FVC at the low levels of exposure typical for most marijuana users. With up to 7 joint-years of lifetime exposure (eg, 1 joint/d for 7 years or 1 joint/wk for 49 years), we found no evidence that increasing exposure to marijuana adversely affects pulmonary function.”

    The study concludes, “Our findings suggest that occasional use of marijuana … may not be associated with adverse consequences on pulmonary function.”

    To those familiar with the science of cannabis, JAMA’s findings should come as no great surprise. They are consistent with previous findings reporting no significant decrease in pulmonary function associated with moderate cannabis smoke exposure. For instance, according to a 2007 literature review conducted by researchers at the Yale University School of Medicine and published in the Archives of Internal Medicine (and summarized by NORML here), cannabis smoke exposure is not associated airflow obstruction (emphysema), as measured by airway hyperreactivity, forced expiratory volume, or other measures.

    Further, in 2006, the results of the largest case-controlled study ever to investigate the respiratory effects of marijuana smoking reported that cannabis use was not associated with lung-related cancers, even among subjects who reported smoking more than 22,000 joints over their lifetime. (Read NORML’s summary of this study here.)

    “We hypothesized that there would be a positive association between marijuana use and lung cancer, and that the association would be more positive with heavier use,” the study’s lead researcher, Dr. Donald Tashkin of the University of California at Los Angeles stated. “What we found instead was no association at all, and even a suggestion of some protective effect” among marijuana smokers who had lower incidences of cancer compared to non-users.

    A previous 1997 retrospective cohort study consisting of 64,855 examinees in the Kaiser Permanente multiphasic health checkup in San Francisco and Oakland also reported, “[E]ver- and current use of marijuana were not associated with increased risk of cancer … of the following sites: colorectal, lung, melanoma, prostate, breast, cervix.”

    Separate studies of cannabis smoke and pulmonary function have indicated that chronic exposure may be associated with an increased risk of certain respiratory complications, including cough, bronchitis, phlegm. However, the ingestion of cannabis via alternative methods such as edibles, liquid tinctures, or via vaporization — a process whereby the plant’s cannabinoids are heated to the point of vaporization but below the point of combustion –- virtually eliminates consumers’ exposure to such unwanted risk factors and has been determined to be a ‘safe and effective’ method of ingestion in clinical trial settings.

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