B62
Determination of HER2 status in invasive breast carcinomas using tissue microarray
Munirah MA1, M.A Siti-Aishah1, Rohaizak M1, M. Rafie MK2, Asmiati A2, Hisham A2, Fuad I1, Sharifah NA1
1Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia, 2Hospital Putrajaya, Selangor, Malaysia
Background
Breast cancer is the most common malignancy in Malaysia. Diagnostic assays for HER2 in breast cancer provide important prognostic information and independently help guide management by identifying patients who are the most likely to benefit from Herceptin-targeted therapy. The aim of this study is to determine HER-2 status in invasive breast carcinomas by tissue microarray and correlating with hormone receptors, p53, MIB-1 and BCL-2.
Method
There were 232 patients diagnosed as invasive breast carcinomas at Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM) and Hospital Putrajaya from years 2004 to 2006. The median age of these patients was 52.4 years. Most patients underwent lumpectomy and / or mastectomy. We use tissue microarray to examine the expression of HER2, p53, estrogen receptors (ER), progesterone receptors (PR), BCL-2 and MIB-1 in only 216 cases of these patients. HER2 for borderline positive (2+) IHC was confirmed by fluorescence in situ hybridization (FISH) using whole sections in these samples.
Results
Of the 26 cases that were analysed for FISH, 23 (80.8%) cases showed HER2 amplification, 3 (11.5%) showed no amplification and 2 cases were non-interpretable. HER2 overexpression was inversely associated with ER status (p=0.0007), PR (p=0.0005) status, and BCL-2 (p=0.0003) but related to grade 3 (p=0.007), lymph node metastases (p=0.015) and the number of involved lymph nodes (mean 4.84; p=0.014). HER2 overexpression was not correlated to age, tumour size, histology type, MIB-1 and p53. Clinical follow-up information of 128 patients was available and 26 (83.9%) patients whose cancers were 3+ were still alive.
Conclusion
HER2 overexpressing carcinomas were associated with prognostic factors of tumour grade and number of nodes involved and inverse relation with hormone receptors and BCL-2.
