On Tuesday the 19th of October an Oireachtas health committee discussing the topic “Breast screening program and improving outcomes for breast cancer with National Cancer Control Program” heard that Cannabis is the leading cause of breast lumps in men. This was a statement made by Prof. Arnold Hill who is the clinical advisor to the National Cancer Control Program. 

When being asked about breast cancer in men by Gino Kenny, TD with People Before Profit, Prof Arnold Hill said that Cannabis is the leading cause of “breast lumps” in men. This wording he uses to the layman sounds like he is saying that cannabis is the leading cause of breast cancer in men given the nature of the topic. 

What Arnold Hill is actually talking about in the video above is “Gynecomastia” which is a condition in males where breast tissue overdevelops leading to an enlargement of the breasts which can be uneven too. It’s often caused by changes in levels of the female hormone (estrogen) and the male hormone (testosterone) but it can be caused by other things as well. Things such as drinking too much cow’s milk which can be a source of estrogen can lead to gynecomastia.

The funny thing about gynecomastia is that its not associated with breast Cancer so why did Arnold Hill even bring it up? Had it anything to do with the fact the person asking the question was TD Gino Kenny who has pushed for medical cannabis access in Ireland and who’s also submitting a bill to legalise and regulate cannabis use in Ireland next month? Also why did the Sunday Times decide to go with the headline about Cannabis and breast lumps rather than Arnold statement that moderate alcohol use can be attributed to 10-12% of breast cancers. (video below)

As we are on the subject of gynecomastia, its link to cannabis use is based on some old studies which suggested that cannabis use leads to a decrease in testosterone in males. These studies(1 , 2) were done at a time when the propaganda machine supporting the war on drugs was in full effect, with money being thrown at researchers to find any harms associated with the use of Cannabis. This propaganda that cannabis lowered sperm count and testosterone was repeated for a number of years with many fear mongering headlines spreading misinformation using these studies. 

More recent research on cannabis use suggests it’s associated with an increase in testosterone (3, 4, 5). The studies not only suggest cannabis users have a higher testosterone to non users but also that the serum testosterone increased as the duration since last use decreased. Meaning those who had most recently used cannabis has the highest testosterone levels, suggesting that possibly taking a dose of your Cannabis before a strength and conditioning class could be a good idea after all. Also showing that the link between cannabis use and gynecomastia is also less likely. 

At a time when governments want us to be listening to health experts to take guidance from, maybe it would be best not to have them attempting to mislead the public like this. It's not as if we can't just take out our phones and do a quick google scholar search to debunk this propaganda

References

1. Dalterio, S., Bartke, A., Roberson, C., Watson, D., & Burstein, S. (1978). Direct and pituitary-mediated effects of Δ9-THC and cannabinol on the testis. Pharmacology Biochemistry and Behavior, 8(6), 673–678. https://doi.org/10.1016/0091-3057(78)90265-4

2.  Dalterio, S. L., Mayfield, D. L., Michael, S. D., Macmillan, B. T., & Bartke, A. (1983). Effects of Δ9-THC and castration on behavior and plasma hormone levels in male mice. Pharmacology Biochemistry and Behavior, 18(1), 81–86. https://doi.org/10.1016/0091-3057(83)90255-1

3. RJ, F., SD, L., TP, K., & R, R. (2020). The effect of tetrahydrocannabinol on testosterone among men in the United States: results from the National Health and Nutrition Examination Survey. World Journal of Urology, 38(12), 3275–3282. https://doi.org/10.1007/S00345-020-03110-5

4. JE, T., BI, G., M, B., H, V., B, T., MB, C., & KA, M. (2017). Marijuana use and serum testosterone concentrations among U.S. males. Andrology, 5(4), 732–738. https://doi.org/10.1111/ANDR.12358

5. Thistle, J. E., Graubard, B. I., Braunlin, M., Vesper, H., Trabert, B., Cook, M. B., & McGlynn, K. A. (2017). Marijuana use and serum testosterone concentrations among U.S. males. Andrology, 5(4), 732. https://doi.org/10.1111/ANDR.12358