Breast cancer is the most common cancer in women (
1). It is one of the most frequent malignancies among Iranian women (
2). The prognosis and survival rates of breast cancer are different in women and related to characteristics including age, tumor stage, and intrinsic properties of the tumors (
3). Moreover, the histological grade and type of tumor are morphological findings that play a main role in breast cancer classification (
4). Markers including Estrogen receptor (ER), Progesterone receptor (PR), and Her-2 can be used in routine clinical labs to predict response or resistance to treatment for using new drugs (
5-
8). Her-2 neu over-expression is associated with poor clinical outcome (
2) and resistance to hormonal therapy (
2). The expression of Estrogen receptor and/or progesterone receptor, as prognostic factors, is predictor of response to endocrine therapy (
2). Moreover, tumors with ER
+/PR
+ are hormone responsive and have a better prognosis in comparison to tumors which are ER
-/PR
- (
2). The significance of ER
+/PR
- tumors, as a distinct subset of breast cancer, has been well documented (
9-
12). But, a debate was seen about the significance of ER
-/PR
+ tumors as a clinically and biologically distinct group of breast cancer (
3).