The rising incidence of breast, testis, and other cancers among adolescents and young adults (AYAs) aged 15 to 39 continues to be a pressing concern, with reported increases of 30% over the past four decades. Factors such as obesity, sedentary lifestyles, chest radiation, alcohol consumption, and hereditary predisposition have been proposed as potential culprits. However, a recent major study suggests that increasing cannabis use among AYAs may also play a significant role.
Study Insights
Conducted by Dr. Rebecca H. Johnson, Medical Director of the Adolescent and Young Adult Oncology Program at Mary Bridge Children’s Hospital in Tacoma, Washington, this study evaluated cancer incidence trends in states that have legalized cannabis versus those that have not, as well as comparing these trends to cannabis use in Canada.
Utilizing annual cancer incidence data from the U.S. Surveillance, Epidemiology, and End Results (SEER) program and Canada’s Institute for Health Metrics and Evaluation (IHME), the research focused on breast cancer incidence in females aged 20–34 and testis cancer incidence in males aged 15–39. The findings revealed that in states where cannabis is legal, breast cancer incidence increased by 26%, compared to 17% in non-legal states, while testis cancer saw increases of 24% versus 14%.
In Canada, where cannabis was legalized earlier and more broadly, the increases were even more significant, with breast cancer rates rising by 35% and testis cancer by 83% in the same period.
Cannabis as a Potential Risk Factor
Dr. Johnson emphasized the implications of these findings, stating, “The evidence from our study implicates cannabis as a potential etiologic factor contributing to the rising incidence of breast cancer in young females and testis cancer in older adolescent and young adult males.” She noted that the carcinogenic effects of cannabis on AYAs appear to manifest rapidly, often leading to cancer development within just a few years of exposure.
Understanding Cannabis Use and Cancer
The study was motivated by a need to examine how the increasing use of cannabis correlates with the rising cancer rates in AYAs, particularly since this demographic demonstrates higher cannabis usage compared to older age groups. Over the past two decades, cannabis legalization has accelerated in the U.S., with 47 states, the District of Columbia, and several territories now permitting medical cannabis usage, and a significant number allowing recreational use.
The potency of cannabis has also increased significantly, with THC levels rising from around 4% in the 1990s to over 14% in 2019, enhancing its exposure effects. Dr. Johnson’s team analyzed SEER data for cancer rates in youths and compared it to the statistics available from Canada, where cannabis was legalized for medical use as early as 2001 and recreational use in 2018.
Hormonal Regulation and Cancer Risk
Cannabis is known to disrupt endocrine functions, impacting reproductive organs through receptors present in both breast and testis tissues. Animal studies suggest that cannabis exposure leads to morphological changes in breast tissue, which may heighten the risk of breast cancer among adolescents. Obesity also plays a potential role, as it could increase both the size of breast adipocytes and the number of cannabinoid receptors, potentially escalating the risk of cannabis-induced breast carcinoma.
Further, cannabis exposure can decrease luteinizing hormone levels—promoting factors that protect against breast cancer, indicating a plausible hormonal link to cancer development.
The Impact of Consumption Methods on Cancer Risk
While the study did not directly address whether smoking cannabis or using THC-infused edibles has different cancer risk profiles, existing literature highlights a connection between smoking cannabis and the development of oropharyngeal cancers, due to the carcinogenic substances similar to those found in tobacco.
Concerns Regarding Treatment Efficacy
Additionally, the study raises concerns about cannabis impacting cancer treatment effectiveness. Research indicated that cannabis users with metastatic breast cancer may experience significantly shorter median survival times compared to non-users. Dr. Johnson advocates for a cautious approach, suggesting that AYAs with breast cancer might want to avoid cannabis altogether.
Community Awareness and Health Considerations
As the cannabis industry evolves in Mississippi and across the U.S., it is crucial to raise awareness about lifestyle factors that may contribute to cancer risk. Reports indicate that processed food consumption among youths is also increasing, which could compound health risks. Just as cannabis legalization unfolds alongside emerging data on health implications, the local community should be informed on these trends to equip AYAs with knowledge for healthier choices.