en Biostatistics Biostatistics پژوهشي Research <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Introduction</b>: The present study aimed at identifying the risk factors associated with overall survival (OS) of breast cancer (BC) patients using multivariate Cox extended models.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Materials & Methods</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: </span></span></b>This retrospective cohort study was conducted on 348 women with BC who were followed up for 10 years. Kaplan-Meier (KM) and log-rank statistics, Cox proportional hazard (PH), and multivariate Cox models were used to analyze the data. STATA V.17 and SPSS V.27 were used for data analysis.<span lang="FA" dir="RTL" style="font-family:"Times New Roman",serif"></span></span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Results</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: &nbsp;</span></span></b>The median age of the patients was 55 years, and the median survival time was 29 months. Five- and 10-year OS were estimated at 93.4% and 88.4%, respectively. The results of multivariate analysis using the Cox model showed that lymph node (LN+) (hazard ratio (HR) = 2.86, P = 0.002), tumor size (HR = 1.99, P = 0.001), and progesterone receptor (PR-) (HR = 4.5, P = 0.002) increase death hazard significantly.</span></span><br> <span style="font-size:9pt"><span minion="" pro="" style="font-family:"><b>Conclusion</b><b><span style="font-size:11.0pt"><span new="" roman="" style="font-family:" times="">: &nbsp;</span></span></b>Prognostic factors indicated that women with lymph node involvement (LN+), positivity of human epidermal growth factor receptor 2 (HER2+), negativity of estrogen receptor (ER-), negative expression of progesterone receptor (PR-), advanced disease grade, and large tumor sizes were more likely to have a high hazard of death than other women.</span></span><br> <br> &nbsp; Breast Cancer, Overall survival, Cox extended models 12 19 http://jbrms.medilam.ac.ir/browse.php?a_code=A-10-804-2&slc_lang=en&sid=1 Khadijeh Mamashli Mamashli-kh@medilam.ac.ir 10031947532846008026 10031947532846008026 No Health faculty, Biostatistics Department, Ilam University of Medical Sciences, Ilam, Iran Hassan Nourmohammadi Nourmohammadi-h@medilam.ac.ir 10031947532846008027 10031947532846008027 No Medicine Faculty, Ilam University of Medical Sciences, Ilam, Iran Kourosh Sayehmiri kourosh86@gmail.com 10031947532846008028 10031947532846008028 Yes Health faculty, Biostatistics Department, Ilam University of Medical Sciences, Ilam, Iran