Marijuana use is common and growing in the United States amid a trend toward legalization. Exposure to tobacco smoke is a well-described preventable cause of many cancers; the association of marijuana use with the development of cancer is not clear.
Lighting up a cigarette has known cancer-causing consequences, but marijuana’s link to cancer has been less understood. Now, after a meta-analysis of 25 studies, scientists say that smoking marijuana heavily for at least a decade heightens the risk of one startling disease: Testicular Cancer.
Co-author Deborah Korenstein, a physician at Memorial Sloan Kettering Cancer Center says that, importantly, this risk is “not huge.”And emphasizes that men who currently use marijuana should be aware that regular use probably does increase this risk. Regular use in the United States is not uncommon: Approximately 13 percent of Americans say they “regularly” smoke, and this rate is higher among people between the ages of 18 and 29.
Smoking Weed Every Day Puts Men at Risk of a Deadly Disease
The researchers discovered that heavy marijuana use (a daily joint for ten years) was associated with the development of testicular germ cell tumors (TGCT), which make up 95 percent of all testicular cancers. Heavy weed smokers had a 36 percent higher chance of developing TGCT than non-weed smokers, the study shows. To clarify, that doesn’t mean that one in three pot smokers will develop cancer, but that the existing baseline risk of developing testicular cancer rises by about a third.
TGCT is the most common cancer in men between ages 20 and 40 and affects about 2 percent of all men. TGCT can grow quickly: Often, men notice a small painless bump on their testicle or change in ball size. They can look for signs of TGCT using a self-exam. Other researchers have connected heavy cannabis use with a higher incidence of testicular cancer. But in this review, the evidence for increased risk of TGCT wasn’t strong. Researchers say that they’ll have to conduct more specific research before they can definitively unravel the complicated testicular health implications of marijuana.
That’s because the study, published last month in the journal JAMA Network Open, was a systematic review that looked for trends among 25 existing studies and datasets that span the last 50 years — meaning that slight differences in methodology make it more difficult to draw conclusive findings. The review explored smoking marijuana’s potential links to dozens of types of cancer, including lung, head, neck, and urogenital cancers.
The Weed-Cancer Connection
Research shows that the properties of marijuana smoke and cigarette smoke may be more similar than people think.
A puff of weed and tobacco both contain carcinogens, substances capable of causing cancer in living tissue. In fact, some research shows toxic gases, such as benzopyrene and phenols, are 20 times higher in unfiltered marijuana than cigarette smoke.
As people tend to smoke larger puffs, hold their breath and inhale more deeply when smoking marijuana than they do cigarettes, that they may be more exposed to harmful properties such as tar and carbon monoxide. Because of this dangerous overlap in the properties of cigarette and marijuana smoke, an uptick in lung cancer seems likely from heavy weed smoking.
Rates of cancer in marijuana users, with ever use defined as at least 1 joint-year exposure (equivalent to 1 joint per day for 1 year), compared with nonusers. Meta-analysis was conducted if there were at least 2 studies of the same design addressing the same cancer without high risk of bias when heterogeneity was low to moderate for the following 4 cancers: lung, head, and neck squamous cell carcinoma, oral squamous cell carcinoma, and testicular germ cell tumor (TGCT), with comparisons expressed as odds ratios (ORs) with 95% CIs.
Some research shows cannabinoids, compounds found in cannabis plants, inhibit the proliferation of cancer cells. More longitudinal studies are needed to determine the relative risks and benefits linking marijuana and cancer.
However, just because the team didn’t find strong evidence showing an increased risk of other types of cancer doesn’t mean weed smokers are totally in the clear, Korenstein says. She notes that the limitations of the data preclude us from drawing firm conclusions.
“I’d hate for people to interpret that to mean that marijuana use is completely safe.”
“The fact is that we don’t know much about the impact of heavy use, use at a very young age, or about non-smoking use.”Lead researcher Deborah Korenstein of the Memorial Sloan Kettering Cancer Center.
Importantly, researchers may have seen the higher rates of testicular cancer because most weed smokers are in fact, young men, while young smoker habits need to be further evaluated, it’s possible that they are at a higher risk.
But there are still a number of unknowns: There’s not enough data on women or the elderly to understand how their marijuana habits might lead to cancer, and the researcher isn’t sure how the drug delivery method — whether someone smokes, eats, or vapes weed — influences cancer rates.
In general, studying how marijuana impacts health has been difficult, meaning many of our assumptions about the drug are based on limited experiments or anecdotal knowledge. The new analysis didn’t correlate weed with any other kinds of cancer, but that doesn’t mean links don’t exist.
Read more information about Marijuana Health Analysis:
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