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A medical oncologist is a doctor who specializes in treating cancer with medication given either intravenously (by vein) or orally (by mouth). In addition to giving medications to treat the cancer, an oncologist also provides support to patients and helps coordinate treatment given by other specialists (including surgical oncologists, plastic surgeons, and radiation oncologists).
For a patient with stage I, II or III breast cancer, medication may be given before surgery to reduce the size or extent of the tumor ("neoadjuvant") or may be given after surgery ("adjuvant"). For cancer that has spread outside the breast and lymph nodes to a distant region (like the liver, bone, or lungs), medication will be a very important way to control and manage the cancer.
There are a wide variety of effective medicines used to treat breast cancer of all stages. Many factors are taken into consideration by the treating oncologist in determining the most appropriate medicine to prescribe including the stage of cancer, the patient's general health condition or other medical problems and the particular subtype of breast cancer.
The subtype of breast cancer is determined by evaluating what proteins are expressed in the tumor cells. The majority of breast cancer has expression of hormone receptors (estrogen receptor, ER and/or progesterone receptor, PR). When the tumor is hormone receptor positive, anti-hormonal therapies (usually pills, such as tamoxifen or aromatase inhibitors) are very effective treatments. When the tumor has over-expression of the HER2 receptor, biologically targeted therapies, such as trastuzumab are used to treat the cancer.
Chemotherapy, which works by killing rapidly dividing cells, is very useful in controlling disease or preventing recurrence for many stages and subtypes of breast cancer. Depending on the stage of and the molecular subtype of cancer a patient may receive one or all of these types of therapies.