Objectives. Breast cancer is a histological, morphological and molecular heterogenous disease. Like clinical outcomes and prognoses of different subtypes, etiologies might also be different. Therefore, epidemiologic risk factors like sociologic, demographic, antropometric, reproductive, and menstrual factors can be considered as an entity reflected in tumor features. This study was planned to explore the relation between well known risk factors of breast cancer and histological and molecular features of the tumor. Materials and Methods. Epidemiologic data for 250 breast cancer patients followed-up by our clinic and 250 healthy individuals without any diagnosis of malignancy were obtained. The data displaying a relation to breast cancer are age, height, weight, body mass index (BMI), place of birth and province, educational level, menstrual status, age of menarche and menopause, number of births, age at first childbirth, family history of breast cancer, history of smoking and hormone treatment, mammographic screening, and presence of benign lesions. The tumor characteristics of patients in the breast cancer group were recorded. Results. Advanced age, nulliparity, low educational level, irregular mammographic screening, early menarche and late menopause, and high BMI in postmenopausal period were found to be related to increased breast cancer risk. Striking results in terms of the relation between epidemiological factors and tumor features were the early diagnosis of breast cancer in patients with regular mammographic screening. Tumor size was decreased with increased age and increased with increased BMI. Advanced age, prolonged lactation, increased number of births, and high education level were found to decrease axillary involvement. Conclusions. Multiparity still continues to be the strongest protective factor against breast cancer in our society. The decrease in menarche age may be an early sign of the increased breast cancer incidence. Women should be informed about the relation between postmenopausal obesity and breast cancer and encouraged to attend physical activity and exercise programmes. Regular physical examination and mammographic screening are protective against breast cancer.