en Genetics Original/Research Article <div style="text-align: justify;"><strong>Introduction:</strong> Proliferation of cancer cells and the potential of metastasis depend on the activity of different biomarkers such as proliferative ones. Proliferative biomarkers including ki-67, cyclin E1, cyclin D1, p27, and p21 were analyzed through immunohistochemistry (IHC) in previous studies.<br> <strong>Methods: </strong>The current study aimed at investigating the utilizing role of RT-PCR in studying proliferative biomarkers including Ki-67, Cyclin E1, Cyclin D1, P27, and P21 to figure out the association between proliferative biomarkers and clinical aspects in patients with early breast cancer. One hundred and twenty-three patients with primary breast cancer were entered in the current study. Patients&rsquo; clinicopathological characteristics were obtained and also expressions of the proliferative biomarkers were investigated through RT-PCR on both cancerous and normal adjacent breast tissue.<br> <strong>Results:</strong> It was observed that in contrast to Cyclin D and P27, expression of Ki-67, Cyclin E, and P21 were higher in tumor samples compared with normal adjacent tissue. In addition, Cyclin D was higher in ER/PR positive and HER2 negative tumors and it was also higher in greater tumor size. Similarly, Cyclin E expression was higher in greater tumor size. Furthermore, patients with higher expression of P27 experienced worse prognosis.<br> <strong>Conclusions: </strong>Studying the proliferative biomarkers via a quantitative and automated method in Iranian patients showed that proliferative biomarkers had correlations with clinical aspects. Further studies to analyze the clinical utility of proliferative biomarkers in greater populations are warranted.</div> Breast Cancer, Clinical Utility, Clinicopathological Aspects, Proliferative Biomarkers, RT-PCR 20 28 http://mcijournal.com/browse.php?a_code=A-10-184-1&slc_lang=en&sid=1 Sepideh Mansouri sepide.mansurii@gmail.com 10031947532846001624 10031947532846001624 No Recombinant Proteins Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran. Rezvan Esmaeili esmaeili.rezvan@gmail.com 10031947532846001625 10031947532846001625 No Genetics Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran. Ahmad Kaviani akaviani@tums.ac.ir 10031947532846001626 10031947532846001626 No Department of Surgery, Tehran University of Medical Sciences, Tehran, Iran. Mahdi Rezaei rezaei.ut@gmail.com 10031947532846001627 10031947532846001627 No Genetics Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran. Nasrin Abdoli nabdoli@gmail.com 10031947532846001628 10031947532846001628 No Genetics Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran. Parisa Mokhtari-Hesari mokhtarihesariparisa@yahoo.com 10031947532846001629 10031947532846001629 No Integrative Oncology Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran. Leila Farahmand laylafarahmand@gmail.com 10031947532846001630 10031947532846001630 No Recombinant Proteins Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran. Keivan Majidzadeh-A kmajidzadeh@razi.tums.ac.ir 10031947532846001631 10031947532846001631 Yes Genetics Department, Breast Cancer Research Center, Motamed Cancer Institute, ACECR, Tehran, Iran.