Immunohistochemistry for breast cancer generally looks at several metrics such as ER, PR, HER-2, and Ki-67 to assess patient prognosis and develop the next step in treatment.
ER indicates estrogen receptor, and the higher the plus sign indicates higher estrogen levels, the better the outcome with endocrine therapy, and the lower the probability of recurrence and metastasis. PR is progesterone receptor, and the higher the plus sign of PR expression, the lower the probability of recurrence, metastasis, and mortality. When ER and PR are both (+) then the prognosis is best and endocrine therapy can be used postoperatively or preoperatively. If one is positive and one is negative, estrogen-positive (ER+) is better than progestin-positive (PR+), and endocrine therapy remains effective. However, if both are negative (-) then they are not hormonally regulated, and then the prognosis is the worst – there is no weakness and no control in this group of offenders.
Her-2 is associated with the ability to choose targeted therapy in breast cancer patients. Her-2(-), for breast cancer tissue that is Her-2 negative, Her-2(+), which is 1 plus, for breast cancer with mild Her-2 expression, and Her-2(++++), which is 3 plus, for breast cancer tissue with HER2 overexpression. In between, Her-2(++), which is 2 plus signs, is called moderate Her-2 expression in breast cancer tissues, which is more complicated and requires further molecular testing, and if FISH is positive, the presence of Her-2 overexpression can be confirmed. breast cancer with Her-2(-) and Her-2(+) do not require targeted therapeutic agents, while Her-2 overexpression breast cancers are candidates for targeted therapeutic agents.
Ki-67: The lower the tumor cell expression, the better, it is an antigen that marks the proliferative state of the cell. ki-67 function is closely related to mitosis and is essential in cell proliferation, and positivity indicates active cancer cell proliferation.