Prostate cancer (PC) is a major health concern, being the second most common cancer and the fifth leading cause of cancer-associated death among men worldwide. With approximately 1.4 million new cases and 375,000 deaths annually, understanding risk factors and potential protective measures is crucial. Known risk factors for PC include age, African-American ethnicity, and certain genetic markers. However, potential protective factors are less well understood. Recent preclinical studies suggest that cannabinoids, compounds found in cannabis (marijuana), may have anti-tumor properties in PC. This cross-sectional study investigates the association between marijuana use and PC prevalence using data from the National Survey on Drug Use and Health (NSDUH) spanning 2002 to 2020.
Materials and Methods
Data Source
This study utilized NSDUH data from 2002 to 2020, a comprehensive survey administered by the U.S. Department of Health and Human Services. The NSDUH includes noninstitutionalized persons aged twelve and older across all 50 states and the District of Columbia. The survey employs multistage sampling to select household addresses, and interviews are conducted online or in-person. Participants receive $30 for completing the interview.
Inclusion and Exclusion Criteria
The analysis focused on males aged fifty years or older who self-reported ever having testicular or prostate cancer. Participants below fifty were excluded due to the low incidence of PC in this age group. This age cutoff also minimized misclassification of testicular cancer cases, which are more common in younger men.
Dependent Variable
The primary dependent variable was self-reported PC, determined by asking participants if a medical professional had ever diagnosed them with testicular or prostate cancer.
Independent Variable
Marijuana use was categorized into three groups: current users (used marijuana in the last 30 days), former users (used marijuana but not in the last 30 days), and never users (never used marijuana).
Confounders and Covariates
Potential confounders included tobacco and alcohol use, race/ethnicity, age, education, marital status, military service, urbanicity, income, and insurance status. These factors were considered due to their potential influence on both cancer risk and marijuana use.
Statistical Analyses
Chi-Square tests were used to compare frequencies of independent variables and covariates by PC status. For continuous variables, t-tests were conducted. A stratified Cochran-Mantel-Haenszel test assessed the association between marijuana use and PC, controlling for age and race/ethnicity. Multivariable logistic regression models were used to adjust for confounders and estimate odds ratios for having PC.
Results
Sample Description
The study included 2503 males aged fifty or older. Most participants were over sixty-five (69%), married (60.9%), had some college education (73%), reported an income over $50,000 (64%), and lived in metropolitan areas (77.8%). Nearly all had some form of medical insurance, and 40% had served in the armed forces. The majority were non-Hispanic white (89.8%), with smaller percentages of non-Hispanic black (4.8%), Hispanic (3.2%), and non-Hispanic others (2.3%).
Prostate Cancer Prevalence
Prostate cancer was reported by 36% of participants. PC prevalence was higher among those aged sixty-five or older (77.2%) compared to those aged fifty to sixty-four (22.8%). Non-Hispanic blacks had the highest PC prevalence (68%), followed by Hispanics (48%), and non-Hispanic whites (33.9%).
Marijuana Use and Prostate Cancer Prevalence
Current and former marijuana users had lower PC prevalence compared to never users (31.7% and 31.6% vs. 39.9%, respectively). In the older age group (≥65), marijuana users had a significantly lower PC prevalence (36.4%) compared to non-users (42.4%). Similar trends were observed in non-Hispanic whites, with lower PC prevalence among users (28.9%) compared to non-users (38.3%).
Multivariable Analyses
Former marijuana users had a significantly lower prevalence of PC compared to never users (OR = 0.74, 95% CI 0.62–0.90, p = 0.001). Current use suggested a reduced prevalence but was not statistically significant (OR = 0.77, 95% CI 0.52–1.14, p = 0.198), likely due to a smaller sample size. As expected, older age and non-Hispanic black ethnicity were associated with higher PC prevalence.
Discussion
The study looked at data from a big national survey and found that people who used marijuana in the past had a lower chance of developing prostate cancer. However, for those currently using marijuana, the results were less clear, possibly because there weren’t enough participants in this group to draw strong conclusions.
The study’s findings align with earlier lab research, which showed that cannabis can help fight prostate cancer. It does this by disrupting the cancer cells’ life cycle, causing them to die, and preventing them from spreading and forming new blood vessels.
In essence, past marijuana use seems to be linked to a lower risk of prostate cancer, and this supports previous studies suggesting that cannabis has properties that can combat cancer.
Higher PC rates in non-Hispanic blacks can be attributed to genetic, healthcare, and socioeconomic factors. Genetic variations and distinct genomic alterations in prostate tumors contribute to more aggressive disease in black individuals. Healthcare disparities, mistrust in the system, and limited access to treatment exacerbate these issues.
The study has limitations, including potential selection bias, the cross-sectional design preventing causal inferences, and the inability to assess dose-dependent effects of marijuana. Despite these limitations, the study strengthens the evidence for a potential protective role of cannabinoids against PC.
Conclusion
This study is the first to investigate the association between marijuana use and PC in a large, national cohort of older males. The findings suggest that former marijuana use is associated with a lower prevalence of PC, providing a basis for future prospective studies to explore the potential anticancer properties of cannabinoids in medical marijuana.
Source: NCBI