Animal models are compelling that activating the beta-adrenergic pathway (via stress) results in tumor growth and metastasis. Beta-blockers blunt this effect in animals. All of Us could design a randomized intervention trial to test this potential benefit in humans. An observational approach could also be taken with careful attention to pharmacoepi principles and biases such as confounding by indication.
Prostate cancer has long been suspected to include an infectious etiology, although no agent has been identified. It is possible that one specific virus or bacterium is not significant, but rather the characteristics of the entire microbiota to which the prostate is exposed (e.g., the abundance and diversity of all microorganisms). This may be capturable by examining the seminal fluid microbiome.