The UNBC website says.
As part of a retrospective study, Dr. Callaghan and his team looked at data from young men conscripted for military service in Sweden in 1969 and 1970, and tracked their health conditions over the following 42 years. They found that heavy cannabis use (defined as more than 50 times in a lifetime, as measured at conscription) was associated with a 2.5-fold increased risk of developing testicular cancer.
“At this time, surprisingly little is known about the impacts of cannabis on the development of cancer in humans,” said Dr. Callaghan, the study’s lead author. “With Canada and other countries currently experimenting with the decriminalization or legalization of recreational cannabis use, it is critically important to understand the potential harms of this type of substance use.”
The results from the recent study, as well as three prior case-control studies in this area, suggest that cannabis use may facilitate later onset of testicular cancer.
“Our study is the first longitudinal study showing that cannabis use, as measured in late adolescence, is significantly associated with the subsequent development of testicular cancer. My hope is that these findings will help medical professionals, public health officials and cannabis users to more accurately assess the possible risks and benefits of cannabis use.”
The project included an international team of researchers from Karolinska University in Sweden and the Division of Cancer Epidemiology and Genetics at the National Cancer Institute in the U.S. The study is part of Dr. Callaghan’s ongoing research assessing the potential health risks associated with cannabis use and the potential impacts of cannabis legalization on use and related harms.
Background: Given current drug policy reforms to decriminalize or legalize cannabis in numerous countries worldwide, the current study assesses the relation between cannabis use and the development of testicular cancer.
Methods: The study included a population-based sample (n = 49,343) of young men ages 18–21 years who underwent conscription assessment for Swedish military service in 1969–1970. The conscription process included a nonanonymous questionnaire eliciting information about drug use. Conscription information was linked to Swedish health and administrative registry data. Testicular cancers diagnosed between 1970 and 2011 were identified by International Classification of Diseases-7/8/9/10 testicular cancer codes in the Swedish National Patient Register, the Cancer Register, or the Cause of Death Register. Cox regression modeling was used to estimate the hazards associated with cannabis use and time to diagnosis of testicular cancer.
Results: No evidence was found of a significant relation between lifetime “ever” cannabis use and the subsequent development of testicular cancer [n = 45,250; 119 testicular cancer cases; adjusted HR (aHR), 1.42; 95% confidence interval (CI), 0.83–2.45]. “Heavy” cannabis use (defined as usage of more than 50 times in lifetime, as measured at conscription) was associated with the incidence of testicular cancer (n = 45,250; 119 testicular cancer cases; aHR 2.57; 95% CI, 1.02–6.50).
Conclusions: The current study provides additional evidence to the limited prior literature suggesting cannabis use may contribute to the development of testicular cancer.
Impact: Emerging changes to cannabis drug policy should consider the potential role of cannabis use in the development of testicular cancer. Cancer Epidemiol Biomarkers Prev; 26(11); 1644–52. ©2017 AACR.
This article is featured in Highlights of This Issue, p. 1579