Characteristics of Breast Cancer Patients in Northeastern Iran: A Retrospective Cohort Study.

BACKGROUND: Breast cancer (BC) is a complex disease characterized by various demographic and clinicopathological factors. Understanding the prevalence and interrelationships of these factors across regions is essential for clarifying disease progression, improving prevention and early detection strategies. DESIGN: This retrospective cohort study included 4043 female breast cancer patients treated at a radiotherapy & oncology center in northeastern Iran. Due to complete-case analysis, sample sizes varied across analyses. OBJECTIVES: To describe the frequency of demographic and selected clinicopathological characteristics and to investigate their interrelationships. METHODS: Data preprocessing was performed to ensure accurate and effective presentation of the results. Univariate log-linear analyses were first conducted to assess crude associations between variables. Variables of interest were then entered into a multivariable log-linear model adjusted for potential confounders, including age at diagnosis, estrogen receptor (ER) status, and progesterone receptor (PR) status. RESULTS: Patients residing in rural areas showed a significant associationwith a time to presentation longer than five months (OR = 1.48, 95% CI = 1.12-1.96), additionally educated patients significantly associated with shorter time to presentation (OR = 0.69, 95% CI = 0.58-0.83). No significant association was observed between age at diagnosis and time to presentation. Likewise, no association was found with various statuses for HR/HER2, or grade and time to presentation. Education, employment, place of residence and marital status showed no statistically significant associations with clinicopathological characteristics. Any observed association in unadjusted models could be explained by age at diagnosis, ER status, or time to presentation. Multiple tumors were associated with higher odds of ER/PR positivity (OR = 1.42, 95%CI = 1.01-1.99) and were negatively associated with age 40-60 compared to those under 40 (OR = 0.64, 95%CI = 0.44-0.93). Tumor laterality showed no statistically significant relationships with hormone receptor (HR) status, histological grade, employment, education, place of residence, or marital status. CONCLUSION: This study identified associations between several variables. However, the observed associations may be influenced by unmeasured factors. Further studies are needed to clarify the underlying mechanisms driving these relationships.