Factors Associated With Testicular Cancer Risk Among New American Military Recruits During Wartime

Testicular cancer (TCa) comprises the majority of peri/postpubertal male neoplasms and has increased in incidence. A review of the literature finds little information on short-term risks associated with mens' occupational choices. The U.S. Army includes a large population in the age range of highest TCa risk. We examined whether combat duty and occupational categories were associated with TCa in this population during a recent period of prevalent combat operations. We employed official medical, administrative and sociodemographic data on 210,483 males new to active-duty service in the U.S. Army during 2011-2014, when combat operations in Afghanistan continued apace and those in Iraq were waning. We calculated TCa diagnosis incidence rates by occupation and service time, compared predictor distributions, and devised a multivariable survival regression model. There were 44 new recruits diagnosed with TCa (period prevalence: 0.02%; incidence rate: 11.61 per 100,000 person-years). Within up to 4 years of service, the adjusted TCa diagnosis risk increased twofold for those in the infantry occupation when compared with other military occupations (p = .045) but was not associated with combat deployment. Adjusted TCa risks increased with age and White race and decreased with service time. Variation in adjusted TCa diagnosis risk by occupation was seen within 4 years following service entry. This variation could have potentially occurred due to selection effects for which we could not control, yet causative occupational exposures cannot be ruled out with our data. The results suggest the need for further research to identify causal pathways and risk mitigation strategies.