HER-2/neu overexpression in invasive ductal breast cancer - an association with other prognostic and predictive factors

SUMMARY Background: HER-2/neu is a proto-oncogene that is amplified/overexpressed in 15 to 30% of invasive breast cancers. The pur- pose of this study was to determine if any relationship exist between HER-2/neu protein overexpression and estrogen receptor (ER), progesterone receptor (PR), grade, size, and lymph node status in female breast cancer. Methods: A total of 100 cases of invasive ductal breast cancer were included in this study. The hormone receptors and HER- 2/neu were studied immunohistochemically (IHC). Using the HER-2/neu DAKO scoring system, scores of 0, 1+ and 2+ were defined as negative and 3+ as positive. Results: HER-2/neu protein overexpression was seen in 20 (20%) of cases. HER-2/neu protein overexpression was present in 4 of 52 T1 lesions (8%), in 11 of 37 T2 lesions (30%), in 3 of 6 T3 lesions (50%), and in 2 of 5 T4 lesions (40%), (p<0.05). Protein overexpression was seen in 7 of 17 grade III tumors (41%), and 13 of 61 grade II tumors (21%). Overexpression was not detected in grade I tumors (p<0.01). Of the 20 Her-2/neu positive cases, ER- and PR-negative status was detected in 60% and 70%, respectively.