Introduction: Breast cancer is acknowledged as the most prevalent form of cancer in women. The aim of the present study was to examine tumor-related biomarkers such as ER, PR, HER2/neu, P53, Ki-67, CEA, CA-125, and CA 15-3 in women with breast cancer referred to Naft Hospital of Ahvaz, southwest Iran. Methods: This research was a cross-sectional investigation. A total of 100 Iranian women patients were selected who were diagnosed with breast cancer tumors (stage 3). All tumor markers like CEA, CA 15-3, and CA-125 were determined using a chemiluminescent instrument. In addition, the immunohistochemical technique was used to analyze the expression of ER, PR, HER/neu, Ki-67 antigen, and P53 protein. Results: The mean of patients' age was 48.53 ± 9.57 years. ER accounted for the highest frequency (73, or 73%) out of 100 cases. There were 69 (69%), 55 (55%), and 53 (53%) positive cases for PR, HER2/neu, and P53, respectively. The chi-square analysis revealed a significant difference for HER2/neu and P53 biomarkers (p = 0.027). The odds ratio was 2.625 [95% CI: (1.167-5.906)], and the positive correlation between them was 0.236 (p = 0.018). Moreover, a significant difference was found for ER and PR biomarkers (p < 0.0001), and the odds ratio was 18.25 [95% CI: (7.039- 47.319)]. There was a significant positive correlation (r = 0.908, p < 0.0001) between ER and PR. A remarkable positive correlation (r = 0.256, p = 0.010) was also observed between CEA and CA 15-3 biomarkers. Conclusion: Our findings indicated that the highest frequency of tumor-associated biomarkers was ER, and there was a positive correlation between ER and PR, HER2/neu, and P53, as well as CEA and CA 15-3.