Rising risk of testicular cancer by birth cohort in the United States from 1973 to 1995.

PURPOSE Recent epidemiological studies have demonstrated an increasing incidence of testicular cancer in white men which appears to be correlated with the period of birth. Because this birth cohort phenomenon can explain etiological factors in testicular cancer, we determine whether this trend is present throughout the United States based on an analysis of testicular cancer incidence by birth cohort. MATERIALS AND METHODS Testicular cancer incidence was obtained from the National Cancer Institute Surveillance, Epidemiology and End Results database from 1973 to 1995. Numbers of cases were extracted and grouped by 5-year birth cohorts for all testicular germ cell neoplasms. Poisson regression analysis with variables of age, time of diagnosis and birth cohort were used to determine relative risk. Poisson models were compared using computer log linear model software. RESULTS Between 1973 and 1995 the incidence of testicular cancer in the United States increased 51% (3.61 to 5.44/100,000). Analysis of Poisson models revealed that birth cohort was strongly associated with relative risk of testicular cancer (p = 0.001). In addition, peak age at diagnosis decreased for each successive birth cohort. CONCLUSIONS The overall incidence of testicular cancer in white men and the relative risk of testicular cancer have been increasing in the United States. This trend is strongly associated with birth cohort in concordance with previously reported European data. Moreover, testicular cancer is being diagnosed at a younger age as evidenced by a shift to the left in the age of peak incidence. These unique epidemiological patterns offer a basis for analysis of potential etiological factors.