Breast cancer is a major public health problem both in the world and in our country. It is the most common cancer in women in the Republic of Croatia, affecting one quarter of newly diagnosed women with cancer. If breast cancer is detected at an early stage, the chances of survival and cure are much higher. It is mostly diagnosed in women over the age of 50, but is increasingly occurring at an earlier age. Life habits that include diet, supplement consumption, and physical activity greatly affect the quality of life of breast cancer patients. 97 women with breast cancer participated in this study. The research was conducted in the form of an online questionnaire through the Facebook pages of various associations that advocate for people with breast cancer. The results obtained on the physical activity of the patients are in accordance with the recommendations for physical activity. The results on the diet are not in line with the recommendations. Respondents should increase their intake of protein, whole grains, fiber, fruits and vegetables, and reduce their fat intake. You should consult your doctor or nutritionist about consuming supplements. The results indicate that the respondents were poorly informed about the possible side effects of dietary supplements with the drugs they use.