e17024 Background: In Italy, 2.300 new testicular cancer (TCa) were estimated in the year 2020. The aim of this study was to examine the incidence and mortality trends, the 5-year relative survival by histopathology of tumours and the association with second neoplasms in TCa patients (pts) of Reggio Emilia (RE) Province. Methods: The population-based cohort study used data from the RE Cancer Registry (RE-CR) and all TCa recorded from 1996 to 2020 were included, evaluated by age ( < 30; 30-40; 40+), histotype and year of diagnosis (1996-2000; 2001-2005; 2006-2010; 2011-2015; 2016-2020). Population estimates are represented by the general population of the RE Province recorded on January 1st of each year. The standardized incidence rate was calculated using the European population and the Annual Percent Change (APC) was reported. The 5-year relative survival was estimated using the Pohar Perme method. Trends over time were analysed by calculating the APC in age-standardized rates using Joinpoint Regression. Results: 385 pts with TCa were considered, 244 (63.4%) seminomas and 141 (36.6%) non-seminomas, 153 cases (39.7%) aged 30–40 years. There were differences according to age between the different histopathology groups: in the non-seminoma group there were more younger pts (44% aged less than 30 years) while in seminoma group there were 40.2% of pts older than 40 years. The 25-year recording trends showed an annual increase of 2.3% in the annual incidence in seminomas. The incidence of seminomas increased from 36 cases (14.8%) in the period 1996-2000 to 60 cases (24.6%) in the period 2016-2020. The non-seminoma cases remained almost constant during these years. Overall 5-years survival was 95%, 99% and 88% for seminoma and non-seminoma groups, respectively. In seminoma group 5-years survival was higher in all age groups. In patients over 40 years, the 5-years survival was 98% in seminoma group but 64% in non-seminoma group. An association with second tumours was documented in 19 pts (4.9%) after TCa diagnosis. The main second neoplasms were skin (4 pts), lung (4pts) and prostate cancer (3 pts). The median time of second tumors onset after TCa diagnosis was respectively 9.4, 8.5 and 6.7 years. After adjusting for age at diagnosis, logistic regression analysis showed an increased risk for second cancer, odds ratio (OR) = 1.9 (95% CI 0.7; 5.4) among seminoma pts. In addition, the OR was higher in pts aged 30 to 40 years and over 40 years, OR = 1.8 (95% CI 0.4; 9.3), OR = 8.3 (95% CI 1.8; 37.7) respectively. Conclusions: Our data confirm the increase of seminoma incidence, in particular in older ones. The non-seminoma cancers occurred rarely in pts aged over 40 yrs and this group had worst prognosis. This finding requires further studies to highlight emerging risk factors and improve the therapy in poor prognosis pts .