Abstract
BACKGROUND: The overall incidence of breast cancer is different all over the world and even within a nation. The present study aims to investigate the stratum-specific incidence trends of breast cancer in southern Iran. METHODS: In this retrospective cohort study, the data of Fars Population-Based Cancer Registry was used during 2001-2018. New cancer cases with ICD-O-3 codes C50.0 to C50.9 were categorized based on age group, morphology, and topography. Age-specific incidence rates of breast cancer were calculated during 2001-2018. Annual overall and truncated age-standardized incidence rates and their 95% Confidence Intervals (CIs) were also calculated. Afterward, the Annual Percentage Changes (APCs) of the age-specific and age-standardized incidence rates of breast cancer during 2001-2018 were calculated using Joinpoint regression software. RESULTS: An increasing trend was observed in the incidence of breast cancer among women during 2001-2018 (APC of age-standardized incidence rates: 9.5 (95% CI: 7.5, 11.5)).However, the trend was increasing less during the recent years. The APC of age-standardized rates decreased from 15.03 (95% CI: 10.4, 19.8) in 2007 to 6.15(95% CI: 4.0, 8.4) in 2018. The most common morphology of breast cancer was invasive ductal carcinoma (77.3% in females and 75.1% in males) and its trend was similar to the general trend of different types of breast cancer. The most common site of breast cancer was the upper outer quadrant. Most breast cancer cases were female and males accounted for 2.45% of the cases. Among females, 40-55 was the most prevalent age group. CONCLUSION: The incidence of breast cancer among women living in southern Iran showed an increasing trend from 2001 to 2018. However, the rate of increase exhibited a milder slope during the more recent years. Based on the higher prevalence of breast cancer in the 40-55 age group observed in the present study, it offers valuable insight into the potential reduction of the breast cancer screening age from 50 to 40 years for healthy Iranian women. However, before implementing such a policy change, it is crucial to conduct additional studies that specifically examine the cost-effectiveness, as well as the potential benefits and risks associated with this alteration.