Her2

Her2 is a 185 kilodalton protein, a member of the human epidermal growth factor receptor family, which localizes to the cell membrane. It is encoded at 17q12-21.32.

Immunohistochemical expression

It is overexpressed in 20-30% of female breast cancers. In 90% of cases this is secondary to gene amplification.

Diagnostic utility

Her2 amplification predicts prognosis, responsiveness to anthracycline-based chemotherapy and those cancers likely to respond to monoclonal antibody therapy against Her2 (Herceptin, trastuzumab). FISH is the reference standard for assessing Her2 status but is technically difficult. The reproducibility and correlation of Immunohistochemistry with FISH have been questioned. A bright field gold-facilitated autometallographic method (GOLDFISH) for detecting Her2 amplification holds promise of allowing FISH to be performed using Immunohistochemical techniques¹.

Her2 does not appear to be commonly overexpressed in ovarian tumours.

References

¹ Downs-Kelly E, Pettay J, Hicks D, et al. Analytical validation and interobserver reproducibility of EnzMet GenePro: a second-generation bright-field metallography assay for concomitant detection of HER2 gene status and protein expression in invasive carcinoma of the breast. Am J Surg Pathol 2005; 29:1505-11

This page last revised 21.1.2006.

©SMUHT/PW Bishop