[Histonet] CAP Question

Schaundra Walton schaundrawalton <@t> yahoo.com
Mon Apr 16 10:33:56 CDT 2012

I have a question regarding a new CAP checklist question
dealing with ER/PR validation.  The new question is ANP.22976 ER/PgR
Validation and states: 
“If the laboratory performs immunohistochemistry for
estrogen receptor (ER) and/or progesterone receptor (PgR) as a
prognostic/predictive marker on breast carcinoma, the laboratory has documented
appropriate validation for the assay(s).  
 Note: Initial test validation should include a
minimum of 40 cases (20 positive and 20 negative cases) for
FDA-approved/cleared tests; laboratories should consider using higher numbers
of test cases if a Laboratory Developed or Laboratory Modified Test is to be
validated.  Validation should be performed by comparing the laboratory’s
results with another assay that has been appropriately validated. 
Acceptable concordance levels are 90% for positive results and 95% for negative
results.  If significant changes are made to the testing methods (e.g.
antibody clones, antigen retrieval protocol or detection system) revalidation
is required. “ 
Our original validation was done in 2005 and was performed
with 20 cases.  Do we need to revalidate to be compliant with this
question?  Should we start from scratch or just do an additional 20 cases?  
Any feedback is appreciated.
Schaundra Walton BS HTL(ASCP)
Histology Supervisor

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