As per usual, you [Meg] are uneducated on the topic, but you post as if an expert. 
Nailed it… again!
It is an amusing irony that marijuana's strongest opponents continue to claim that marijuana causes cancer. The National Institute of Drug Abuse funded UCLA pulmonologist Prof. Donald Tashkin. For decades Tashkin struggled to demonstrate that smoking marijuana causes cancer, but he finally gave up. Tashkin's 2006 publication of his case-controlled study compared 1,200 patients with lung and head and neck cancers to a control group without cancers. To his credit, Tashkin reported reported the results that flew against his prejudice. He reported that, while tobacco smokers had a twenty-fold risk of cancer compared to non-smokers, marijuana smokers had lower cancer risk than non-smokers.Got that? Marijuana smokers had lower cancer risk than non-smokers!Marijuana Use and the Risk of Lung and Upper Aerodigestive Tract Cancers: Results of a Population-Based Case-Control StudyMia Hashibe; Hal Morgenstern; Yan Cui; Donald P. Tashkin; Zuo-Feng Zhang; Wendy Cozen; Thomas M. Mack; Sander Greenland. Cancer Epidemiol Biomarkers Prev (2006) 15 (10): 1829–1834.
https://doi.org/10.1158/1055-9965.EPI-06-0330Tashkin's findings merely echoed an earlier 1997
National Institute of Drug Abuse funded study of 65,000 Kaiser HMO patients. In turn, those findings in humans were presaged by federally funded animal studies from the 1970s.
Get the memo—the most committed opponents of marijuana (researchers and feds) have been forced to begrudgingly admit that there is no evidence that marijuana causes cancer.
That marijuana smokers have lower cancer risk than non-smokers certainly lends credence to the reports of cancer cures using marijuana.
Sure, marijuana's rabid enemies can point to this or that putatively carcinogenic chemical in marijuana smoke (e.g., aromatic hydrocarbons such as benzopyrene), but whatever those chemicals, it is clear that marijuana's beneficial chemicals have the predominant effect.