Pathological features of invasive ductal carcinoma of the breast according to expression of progesterone receptor
Background: Loss of PR expression in breast cancer is associated with older patients, larger tumors, higher grade tumors and tumors over-expressing HER2. We previously reported that loss of PR expression predicts higher Recurrence Scores (RS) of the 21-gene assay (Oncotype DX) and higher risk for bone metastasis. Recently, a 20% or less PR expression was proposed to separate Luminal B from Luminal A subtype of breast cancer. Here we intend to study the relationship between the different levels of PR expression and various pathologic features in invasive ductal carcinoma (IDC) of the breast.
Design: 3573 cases of primary IDC of the breast from our institution diagnosed between 1997 and 2013 and had an immunohistochemical (IHC) score for ER and PR in exact percentage were included in the study. The clinicopathological features (age, size, nodal status, lymphovascular invasion (LVI) status, histological grade (HG), and expression of ER, PR, HER2 and Ki-67) were collected for each case. The relationships between the levels of PR expression (Results: Among the 3573 cases, the mean age was 59.9 years, the mean tumor size was 2.05cm, 31% had nodal metastasis, 18% had LVI, 85%, 78% and 12.4% were positive for ER, PR and HER2 respectively. 53% showed Ki67 labeling equal or greater to 15%. Significant differences in LVI, HG and ER expression were observed between the PRConclusions: The difference observed in between PR