Breast cancer in reproductive-age women in Croatia: trends, demographic shifts, and correlation with human development index

Introduction Croatia has a moderate breast cancer (BC) incidence rate and lower survival rates compared to other countries. This study examined trends in BC among women of reproductive age (15–49) in the Republic of Croatia from 2001 to 2022, with particular attention to socio-economic and demographic transition. Materials and methods Incidence and mortality data for BC were obtained from the Croatian National Cancer Registry and the Croatian Bureau of Statistics. We used the subnational and gender-specific Human Development Index to assess regional differences and their correlation with BC. The age-standardized rate was calculated per 100.000 women aged 15 to 49 years, using direct standardization to the European Standard Population 2013, and the average annual percent change (AAPC) was determined. The mortality-to-incidence ratio (MIR) was used to monitor long-term cancer control. Results Over 22 years in Croatia, the BC incidence rate increased, with an average of 52.1 (SD = 8.8). The rate was significantly higher in Adriatic Croatia and the City of Zagreb ( F = 14.9, p < 0.001). The AAPC showed a significant upward trend in all regions. The BC mortality rate showed a decreasing trend across regions, except in the City of Zagreb, but this trend was not statistically significant. At the national level, the average mortality rate was 7.8 (SD = 1.2). There is no significant difference in mortality rates between regions ( F = 1.936, p < 0.130). A significant positive correlation was found between HDI and BC incidence, and a negative correlation with MIR across all regions. The correlation with mortality was mainly negative but not significant. Conclusion Breast cancer in this group of women is still increasing, and therefore, it is essential to implement public health policies that will improve prevention, early detection, and personalized treatment.