new(~) test (apparently requires fresh or fresh frozen tumor tissue)--start of more

[Lani]

individualized therapy?

New Test Identifies ER and HER2 Status of Breast Tumors

Allison Gandey
February 20, 2007 — A new genomic microarray test can identify the estrogen-receptor (ER) and human epidermal growth factor receptor-2 (HER2) status of breast tumors, researchers say. The test is reportedly 90% accurate for both receptors, making them comparable to if not better than existing pathology tests. The findings are published online February 15 in Lancet Oncology.

“This is an important step toward developing an integrated genomic test that could determine the status, estimate the risk of relapse, and gauge the endocrine and chemotherapy sensitivity of the tumor," senior author Fraser Symmans, MD, associate professor at the MD Anderson Cancer Center department of pathology, in Houston, Texas, told reporters. The study was funded by the National Cancer Institute, the Breast Cancer Research Foundation, and the Goodwin Foundation.

An estimated 70% of breast cancers are ER positive, and another 15% to 25% are HER-2 positive. The new study is the latest in an effort by the research team to develop a single test to quickly determine the status of the tumor and guide treatment.

Led by Yun Gong, MD, from the University of Texas MD Anderson Cancer Center, the researchers analyzed breast-cancer cells from 495 patients with a microarray. They used a commercially available Affymetrix U133A GeneChip system for the hybridization and scanning. The samples included both fine-needle aspiration biopsies and traditional biopsies.

Results Accurate in Different Patient Populations and Between Labs

The researchers looked at 195 fine-needle biopsy samples to set gene expression thresholds. They then applied these cutoff values to 2 more validation studies involving the remaining samples, which showed that the initial results were both reliable and reproducible.

"The test is accurate in samples from different patient populations and between different laboratories," coauthor Lajos Pusztai, MD, also from the MD Anderson Cancer Center, told reporters.

The microarray tests disagreed with traditional immunohistochemical lab analysis of the tumors by 8% for ER and 11% for HER2. The researchers explain in their paper that this discrepancy is usual when different diagnostic methods are applied to the same samples.

According to a news release, a prospective clinical trial is scheduled to begin at MD Anderson to use these tests to recommend treatment for patients with newly diagnosed breast cancer.

Lancet Oncol.