With the growing culture of marijuana use worldwide for medical use and recreational use - many are worried about it's effects on the lungs and its association with cancer. Users of the substance are worried that the drug may actually cause a higher risk for cancer.
While specialists already know that smoking tobacco cigarettes is a top risk factor for many forms of cancer, it remains unclear whether smoking marijuana can increase cancer risk in a similar way. But, looking at the limited number of studies does give a certain idea of the correlation between the two.
How Does Marijuana Affect Cancer or Cancer Risk?
Northern California Institute of Research and Education in San Francisco and other collaborating institutions recently conducted a systematic review and meta-analysis of studies assessing this potential association.
In their paper — which appears in JAMA Network OpenTrusted Source — they recur that marijuana joints and tobacco cigarettes share many of the same potentially carcinogenic substances.
"Marijuana smoke and tobacco smoke share carcinogens, including toxic gases, reactive oxygen species, and polycyclic aromatic hydrocarbons, such as benzo[alpha]pyrene and phenols, which are 20 times higher in unfiltered marijuana than in cigarette smoke," write first author Dr. Mehrnaz Ghasemiesfe and colleagues.
"Given that cancer is the second leading cause of death in the United States and smoking remains the largest preventable cause of cancer death (responsible for 28.6% of all cancer deaths in 2014), similar toxic effects of marijuana smoke and tobacco smoke may have important health implications," they elaborate.
Eight of these studies focused on lung cancer, nine looked at head and neck cancers, seven examined urogenital cancers, and four covered various other forms of cancer. The studies found associations of different strengths between long-term marijuana use and various forms of cancer. The researchers noted that the study results regarding the link between marijuana lung cancer risk were mixed — so much so that they were unable to pool the data.
For head and neck cancer, the researchers concluded that "ever use," which they define as exposure equivalent to smoking one joint a day for 1 year, did not appear to increase the risk, although the strength of the evidence was low. However, the studies produced mixed findings for heavier users. There was insufficient evidence to link this drug to a heightened risk of nasopharyngeal carcinoma, oral cancer, or laryngeal, pharyngeal, and oesophagal cancers.
Among urogenital cancers, the investigators found that individuals who had used marijuana for more than 10 years appeared to have a higher risk of testicular cancer — more specifically, testicular germ cell tumors. Once again, however, the strength of the existing evidence was low.
There was insufficient evidence that marijuana use was associated with an increased risk of other forms of cancer, including prostate, cervical, penile, and colorectal cancers.
Other studies and researches of smoked marijuana found that it can be helpful in treating nausea and vomiting from cancer chemotherapy. They have also found that inhaled (smoked or vaporized) marijuana can be helpful treatment of neuropathic pain (pain caused by damaged nerves). Smoked marijuana has also helped improve food intake in HIV patients in studies.
More recently, scientists reported that THC and other cannabinoids such as CBD slow growth and/or cause death in certain types of cancer cells growing in lab dishes. Some animal studies also suggest certain cannabinoids may slow growth and reduce the spread of some forms of cancer.
There have been some early clinical trials of cannabinoids in treating cancer in humans and more studies are planned. While the studies so far have shown that cannabinoids can be safe in treating cancer, they do not show that they help control or cure the disease.
Relying on marijuana alone as treatment while avoiding or delaying conventional medical care for cancer may have serious health consequences.
Because marijuana plants come in different strains with different levels of active compounds, it can make each user’s experience very hard to predict. The effects can also differ based on how deeply and for how long the user inhales. Likewise, the effects of ingesting marijuana orally can vary between people. Also, some chronic users develop an unhealthy dependence on marijuana.
In conclusion, studies have no direct hint for explaining the relation between cancer and marijuana since the research is limited. But, the drug does have other side effects like - it lowers the user’s control over movement, causes disorientation, and sometimes causes unpleasant thoughts or feelings of anxiety and paranoia. So even though we can't point out whether marijuana and cancer are linked in any way just yet, the other side effects, however, remain the same.