Breast cancer is considered a systemic disease i.e. apart from the cancer in the breast, microscopic cells are considered to be in circulation in the body that may deposit and form a tumor nidus elsewhere in body (metastasis). So breast cancer is treated with multimodality therapy including surgery, chemotherapy, hormone therapy, radiation therapy and/or biological therapy. Any primary breast cancer that is more than1cm in size needs systemic therapy which is usually chemotherapy. Your oncologist will order estrogen receptor ER, progesterone receptor PR and Her2 neu receptor status on the histopathology specimen of the removed breast cancer. If ER and/or PR status is positive then chemotherapy will be followed by hormone therapy as well and if Her2 neu receptor status is positive then a year of biological therapy with trastuzumab will also be given after chemotherapy. Radiation therapy is given after considering certain features in hitopathology report. I hope your query has been answered. If you have any further questions I will be happy to answer. Thankyou for choosing Healthcare Magic.