Breast Cancer from Molecular Point of View: Pathogenesis and Biomarkers

Abstract

1.1 Breast cancer and risk factors Breast cancer is the most common female cancer, the second most common cause of cancer death in women, and the main cause of death in women ages 40 to 59 (1). It has been reported that mortality rate from breast cancer has been significantly greater in women whose cancer was first diagnosed during pregnancy compared with those who had never been pregnant (2). Nowadays, many women all over the world faced the challenge of living with breast cancer. The lifetime probability of developing breast cancer is one in six overall (3). High prevalence of breast cancer and high mortality rate of women who stricken by, appoint it among the most challenging subjects in the area of experiments. The two major types of breast cancer risks are objective and subjective factors. Objective breast cancer risk is defined as an estimated chance for bearing breast cancer based on scientifically established risk factors for the disease and is predictive of resultant health outcomes. Subjective breast cancer risk is identified as an individual’s realization of her chance for getting breast cancer based on her own cognitive appraisal and is affected by depressive conditions. Objective BC risk had a limited but significant relationship with immune response and natural killer cell activity (NKCA), whereas Subjective risk was highly associated with psychological distress but was not associated with NKCA also the results are still controversial (4). Many factors including prenatal conditions, diet, physical activity, estrogen exposure, body mass index, depression and quality of life have been mentioned as breast cancer risk factors. A positive family history is the main risk factor. Diet with high amounts of alcohol, fat, caffeine and red meat is a positive risk factor for bearing breast cancer, whereas phytoestrogens and high amounts of calcium/vitamin D can be effective to reduce it (5,6). Hormonal conditions stand among the most important factors. Prolonged exposure to and higher concentrations of endogenous estrogen; which is controlled and modulated by menarche, pregnancy, and menopause; increase the risk of breast cancer. Testosterone level has also showed some parallelism with higher rate of breast cancer in some studies, although not in all of them. Younger age of menarche and older age of first full-term pregnancy are associated with a higher risk of breast cancer. The data about the effects of oral contraceptives on breast cancer risk are controversial. Some studies show an increased risk of breast cancer in oral contraceptive users, whereas in some other researches, no significant difference was seen. The two newer researches didn’t give any data which show