Scoring index for prediction of HER-2 status in the invasive breast carcinoma

Detection of HER-2 status represents conditio sine qua non for appropriate therapeutic management of patients with invasive breast carcinoma (IBC). We aimed to modify a DIVER scoring index (sec. Taucher et al., 2003) used for the assessment of HER-2 status probability in IBCs.

660 cases of IBC with determined HER-2, estrogen (ER) and progesterone (PR) receptor status and histologic grade (HG) were included in the study. The HER-2, ER and PR were examined immunohistochemically. Cases showing an HER-2 score of 2+ (n = 38) were further tested by chromogenic in situ hybridisation to confirm or exclude HER-2 gene amplification. Based on the correlation of HER-2 with HG, ER, and PR a score index (HERSI) was designed to set a probability score for evaluation of HER-2 status. This index summarizes the individual score of HG, ER, and PR as follows: HG1 = 2 points, HG2 = 1 point, HG3 = 0 points; a negative ER or PR status = 0 points, a positive ER, or PR status 50% of the cells = 2 points. In regard to the final score (0-6 points), cases were divided into subgroups.

HER-2 status was positive in 80 cases (12.1%). A statistically significant correlation between HER-2 and HG, ER, PR status was proven (p < 0.0001). In the subgroup with an HERSI score of zero, HER-2 positive status was found in 30.9%, while in the subgroup with an HERSI score of 5-6 points in only 1.2% of cases. The probability of a positive HER-2 status for cases with a score of 1-4 was approximately 25% (OR = 0.255; CI = 0.155-0.421) and for cases with a score of 5-6 only 2.6% (OR = 0.026; CI = 0.006-0.111) in comparison to the control group.

The proposed scoring index allows significant prediction of HER-2 status in IBCs.