Quantitative PCR and HER2 Testing in Breast Cancer

Abstract

We performed a technical and cost-effectiveness analysis of quantitative reverse transcription-polymerase chain reaction (Q-RT-PCR) for the assessment of HER2 in breast cancer. We evaluated 44 frozen and 55 formalin-fixed paraffin-embedded (FFPE) breast carcinoma specimens by Q-RT-PCR, immunohistochemical analysis, and fluorescent in situ hybridization (FISH). Immunohistochemical and FISH analyses were performed on individual slides and on tissue microarray. Costs of techniques were calculated to study 1 case and 10 or 40 cases. Q-RT-PCR provided reliable data in frozen and FFPE specimens, which were significantly correlated. HER2 messenger RNA levels were significantly stratified in agreement with immunohistochemical data (P < .05). There was complete concordance between Q-RT-PCR and immunohistochemical results for negative and strongly positive (3+) cases. The intermediate immunohistochemical group (2+), including FISH+ and FISH- cancers, could also be stratified by Q-RT-PCR. Cost analysis documented the advantage of Q-RT-PCR in all US Food and Drug Administration-approved assays. Our data support the use of Q-RT-PCR for testing breast cancer specimens to select patients for HER2 inhibitory therapy.