Abstract
We assessed the joint effect of age at enrolment, age at follow-up, family history of prostate cancer, prostate enlargement and seasonality on prostate-specific antigen (PSA) estimated through log-normal mixed-effects modeling in an Italian cohort of healthy, 45- to 65-year-old subjects over a 4-year period. The median ratio was used as the measure of effect. Median and mean baseline PSA were 0.78 (interquartile range: 0.41–1.50) and 1.27 (95% CI: 1.19–1.35) ng/mL, respectively. A similar median annual increase of 5.7% (95% CI: 4.8%-6.5%) was found for age at enrolment and age at follow-up. Individuals with moderate to severe prostate enlargement had a median PSA ratio of 1.040 (95% CI: 0.919–1.176) and 1.318 (95% CI: 1.128–1.539), respectively. Median ratios of 1.200 (95% CI: 0.026–1.404) and 1.300 (95% CI: 0.915–1.845), respectively, were computed for subjects with only one or more than one prostate-cancer-affected relatives. Regarding seasonality, the highest value was shown in summertime, the lowest in wintertime, and the resulting median ratio was 1.280 (95% CI: 1.117–1.468). Irrespective of age, baseline PSA was in most cases about 1.00 ng/mL with a yearly median variation of about 5% over a 4-year period. Indeed, prostate enlargement, prostate cancer family history and seasonality showed a remarkable impact on PSA measurement. This should be considered when counseling patients with a PSA history.