A prognosis tries to estimate the most probable course and outcome of a disease by looking at various factors related to the disease its-self or more generally to the patient and his/her general health. There are several prognostic factors associated with breast cancer. The most important ones are:
the stage of the cancer (whether it is in the breast only or has spread to lymph nodes or other places in the body)
the histological type of breast cancer, the biological characteristics of the tumor (for example the estrogen-receptor and progesterone-receptor levels or the status of HER2/ErbB2)
the grade of cancer
invasion into the blood vessels
the woman's age
general health
menopausal status (whether a woman is still having menstrual periods)
and whether the cancer has just been diagnosed or has recurred (come back).
