A major hurdle preventing human research on cannabis is that the United States government controversially considers it a Schedule 1 drug under the Controlled Substance Act, meaning that the official position is that it has “no currently accepted medical use,” which limits research into its possible medical value. While the anti-tumor studies cited in the NCI PDQ could be part of a broader argument to remove marijuana from that Schedule 1 classification, they do not provide clear evidence that cannabis can be a viable cancer treatment.
Cannabis has been shown to kill cancer cells in the laboratory (see Question 6)
The mysterious Question 6 (the other item cited by these viral studies as proof of some sort of admission by the government) provides information regarding a number of preclinical trials that have shown some promise at killing cancerous cells. That list includes studies on mice, rats, and cell lines suggesting that some cannabinoids (the group of medically relevant chemicals in cannabis) may be able to selectively kill cancerous cells — including those found in colon, liver, and breast cancers. That list was also not modified in any way between 2014 and mid-2018, save for the addition of one new clinical review added to the PDQ in 2017.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government’s center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
The earliest NIH cannabis PDQ archived on the Internet Archive is a 6 November 2014 version, and the sections related to the potential anti-tumor capabilities of cannabis is identical to the allegedly nefarious July 2015 update. Both include this statement in the “overview section”:
An August 2015 article published on the website PoliticusUSA contains the claim that an update to an National Institutes of Health document included a “quiet” admission that marijuana “kills cancer”:
The “report” in question is the NCI’s Physician Data Query (PDQ) on “Cannabis and Cannabinoids.” The National Cancer Institute maintains a database of peer-reviewed cancer research and publishes regular updates and summaries of this research in a product called known as a PDQ:
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a Engagements include social likes, comments, and shares on social media sites (i.e., Facebook, Twitter, Reddit, and Pinterest). Article covering the same story were combined for engagement.
Finally, we searched for cannabis and its synonyms in the tweets and Facebook posts published between July 2017 and July 2018 by leading cancer organizations, comprising 27 National Cancer Center Network (NCCN) member institutions and four national organizations: the American Society of Clinical Oncology (ASCO), American Society for Radiation Oncology (ASTRO), National Cancer Institute (NCI) and NCCN. We used the Wilcoxon rank-sum test to compare the number of retweets and the Facebook engagement for these tweets and posts by leading cancer organizations with the Buzzsumo data during the same period for the top false news stories from our social media engagement analysis.
While doctor-patient interactions are a crucial venue for the communication of accurate information, many patients who use cannabis may find their primary sources of information outside this relationship. A survey of cannabis users  found that 76% reported learning about cannabis from internet research, family members, or friends. In the digital age, where 46% of adults use the internet as their first source of health information, the most trusted sources of online health information – doctors, medical universities, and the federal government  – still have the potential to influence public opinions. Given the prominence of online information – particularly for those with cancer  – it may be especially important for major oncology organizations to have a robust online engagement policy. However, we found that social media posts by these organizations are minimal and generated significantly less engagement than false news stories (Figure 3 ). While many of the high-impact news stories on cannabis in cancer use terms such as “CBD” and “CBD oil,” tweets and Facebook posts by leading cancer organizations used only “marijuana” or “cannabis,” potentially failing to engage and influence patients searching for newer cannabis products online.
News stories with the most social media engagement
*Monthly state RSV is the normalized fraction of all Google searches within a state containing that search term; the normalization constant is chosen such that the maximum RSV achieved across all searched terms is 100.
This study has several limitations. Social media and online search activity around cannabis do not represent the actual use of cannabis. Further, not all states had RSV data available due to periods with low search volume, limiting generalizability. Finally, we could not determine what proportion of the audience of social media news stories about cannabis as a cancer cure were actual patients.
Social media activities of leading cancer organizations