HER2/neu Marker in Breast Cancer

Quality Management Requirements for HER2/neu Marker in Breast Cancer
Recommendations of the HER2/neu Advisory Committee,Ontario,Canada

The testing laboratory must have an established immunohistochemistry program with sufficient volume to maintain technical/professional knowledge and skill. (The UK guidelines recommend performance of 250 IHC and, if applicable, 100 FISH tests per year1). For Ontario, we recommend a minimum of 20 HER2/neu IHC tests per month or 240 HER2/neu tests per year.

The laboratory must have a quality assurance improvement program that provides for the required quality control and uses quality indicators to determine whether performance is meeting the quality standard.

At least one pathologist from each centre, involved in the reading and interpretation of
immunohistochemical preparations in situ hybridization for HER2/neu, must complete appropriate training.

Quality Assurance Requirements - To be read in conjunction with the Testing Algorithm Schematic
It is recommended that tissue be fixed with 10% phosphate buffered formalin (4% formaldehyde),pH 7.0. The optimal fixation time is 8 to 48 hours.
Antibodies currently used in Ontario include monoclonal antibody CBll (Novocastra), monoclonal antibody TAB250 (Zymed), polyclonal antibody A0485 (DAKO) and the HercepTest Kit (DAKO). Assays using these antibodies have been optimized and instructions must be followed precisely. Other appropriately validated antibodies may be used.

If immunohistochemical detection of HER2/neu is carried out using more than one antibody then the antibodies should be directed at different epitopes.

If the findings with the second IHC antibody remain equivocal/indeterminate, in-situ hybridization (FISH or chromogenic in-situ hybridization [CISH]) testing is required.

Controls using tissue and, if possible, cell lines demonstrating high, intermediate and low level HER2/neu amplification, should be run in parallel with patient testing. Patient tests must be repeated when the controls are non-conforming. The report should include an estimate of the % positive cells as well as intensity of staining. If the HercepTest kit is used, the recommended scoring system of 0-3+ should be reported as well as the percentage of positive cells.

The target turnaround time from receipt of the tissue block in the laboratory to report should be within one week and not longer than two weeks. The laboratory must confirm indeterminate IHC results using either FISH / CISH or arrange to have such confirmation carried out by a named referral laboratory that has agreed to provide this service.

Approximately 15 to 30% cases may require FISH. The laboratory must document and maintain a record of the number of patient samples processed and the number of positives, negatives and indeterminates. The percent positives should be calculated on a regular basis as one of the quality indicators.

REFERENCES
1. Ellis 10, Bartlett J, Dowsett M et al. Updated recommendations for HER2/neu testing in the UK. J Clin Pathol, 2004;57:233-237.
2. W. HannaF,P O'Malley. Updated recommendations from the HER2/neu consensus
meeting-Toronto, Ontario, September 2001. Current Oncology. 2002; 9 (Suppl. 1): S18-
S19.