Busy lifestyle accompanied by stress and unhealthy diet has an effect on a development of various types of diseases. One of them is breast cancer, which is the most common type of cancer among women. The number of new cases diagnosed each year is about 1.7 million, of which 500,000 women decease annually. Breast cancer occurs with an incidence of 60 to 100 per 100,000 women in developed countries, whereas in developing countries the incidence is between 20 to 60 per 100,000 women. In the Republic of Croatia the annual number of diagnosed women is over 2,500 and over 1,000 women died in 2012. It is necessary to know certain risk factors that affect the occurrence of a disease for a more successful prevention. One of the most common and the most aggressive form of breast cancer is ductal carcinoma which makes up 90% of all mammography screenings. Symptoms are unfortunately visible and recognizable only after the disease has already progressed and the early detection of breast cancer with diagnostic procedures (mammography) is one of the most important steps for better chances of further survival. Depending on whether the breast cancer is local / primary operable, local / primary inoperable or metastatic, the treatment is determined and is most often a combination of several treatment methods (radiation therapy, hormonal treatment, chemotherapy, immunotherapy, surgical removal). Drugs that are commonly used in the treatment of breast cancer have different mechanisms of action and their use produces various side effects of which oral side effects are very significant. Complications that may occur during treatment can be acute or chronic, such as mucositis, dysgeusia, xerostomia, osteonecrosis and subsequent secondary infections. These complications can compromise the quality of life of patients and thus result in life-threatening problems (sepsis). It is very important to know how to prevent and reduce their presence to the lowest possible level and that the professional health team (oncologist, radiologist, dentist) and patient are familiar with the unwanted possible oral side effects that can occur as a result of treating breast cancer. For these reasons, it is important to maintain regular oral hygiene and regular dental examinations before, during and after a breast cancer treatment.