Tehran University of Medical Sciences (TUMS) Academic Journal of Surgery 2423-3218 7 1 2024 03 27 25 27 Golareh Saeidpour General Physician, Tehran University of Medical Sciences, Tehran, Iran Marzieh Lashkari Associate Professor, Radiation Oncology, Tehran University of Medical Sciences, Radiation Oncology Research Center, Iran Cancer Institute, Tehran, Iran Ramtin Saeidpour Student Research Committee, Dezful University of Medical Sciences, Tehran, Iran ali mir 2023 12 02 Increasing incidence rate of breast cancer in young women obligates investigations of clinical and pathological features in this age group. Less hormone receptor expressions and more aggressive behavior has been discussed in very young breast cancer patients. In this study pathological data of patients diagnosed with Invasive ductal carcinoma referred to Shariati hospital and Tehran cancer institute between 2015 and 2018 was evaluated in two groups : under 35 years old (Group1) and above (Group2). Each group contained 156 cases.  62.8% and 63.5% Estrogen and Progesterone Receptor expressionwas reported in Group 1 in comparison to 77.6% and 74.4% in Group 2 ( P value= 0.004 and 0.0038). Her2 expression was found in 41% and 21.2% in group 1 and 2 respectively ( P value= 0.0001). There was  41.2 ± 25.2 and 29.6 ± 21.7 reported of Ki67 in Group 1 and 2 ( P value= 0.001). In conclusion negative hormone receptor, positive Her2 expression and higher proliferation rates is found in breast cancer patients under 35-year-old https://ajs.tums.ac.ir/index.php/ajs/article/view/243