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Run
23 (General module) was
accomplished April to June 2008. 131 laboratories participated
and a total number of more than 600 slides was assessed. The overall
distribution of marks were: optimal 31%, good 28%, borderline 21%,
and poor 20%. This is an average distribution but less satisfactory
than in runs 21 and 22, probably due to more challenging markers.
A short
summary of the results is given below. Click on the epitope name to
see the complete assessments for each marker.
Calretinin
(CR): 80 % of the
stains were sufficient, which is a marked improvement. As usual, the
insufficient stains were often based on insufficient HIER and a too
dilute antibody - parameters that should be easy to adjust in the
laboratory. Three Abs (mAb clones DAKCalret1 and 5A5 and pAb 18-0211
from Zymed) work equally well, while two pAbs (760-2700 from Ventana
and 7699/4 from Swant) are less succesful. Almost all labs adjusting
their protocols according to the NordiQC recommendations improved.
E-cadherin (ECAD):
85 % of the stains in this first test were sufficient indicating
that the detection of this epitope is not difficult. The liver cells
are critical stain quality indicators, they must show
at least a moderate membranous reaction with no or only minimal
cytoplasmic staining.
Epithelial cell-cell adhesion molecule
(Ep-CAM): 63 % of the
stains were sufficient, which is not satisfactory. A critical point
is the need for HIER in Target retrieval solution pH 6.1 (Dako). 80
% of the labs adjusting their protocols according to the NordiQC
recommendations improved.
Immunoglobulin Kappa (IgK):
Only 42 % of the stains were sufficient, virtually the same as in
2006. Only pAb A0191/A0192 (Dako) give optimal stains and only in a
minor proportion, emphasizing the need for careful protocol
calibration, based on the staining of the IgK+ mantle cell
population, not the plasma cells.
Immunoglobulin M (IgM):
Only 50 % of the stains were sufficient, an improvement from 2006
but still far from satisfactory. Some laboratories only use anti-IgM for plasma
cells. However, the material provided from NordiQC needs an IgM
protocol aimed at demonstrating membranous IgM, not cytoplasmic, in
order to diagnose lymphomas.
Thyroid transcription factor-1 (TTF-1):
The proportion of sufficient stains has increased from 24 % in 2007
to 43 % in the current run, mainly because many labs have changed
their clone from 8G7G3/1 to SPT24.
Run B5 (Breast module) was accomplished in parallel with run
23. 116 laboratories participated and a total of about 200 slides
were assessed.
Estrogen receptor alpha (ER):
79 % of the stains were sufficient, slightly less than in 2007 and
not satisfactory because of the ER being a treatment marker.
Insufficient HIER and too dilute Ab is still a problem. However,
even with correct protocol settings there are marked differences
between the clones used: In cumulated data from six runs comprising
343 slides, clones 1D5, 6F11 and SP1 give optimal stains in 36 %, 47
% and 68 %, respectively.
HER-2: Only
56% of the stains were sufficient. In this assessment PATHWAY was
far the most robust method. For all FDA approved HER-systems
the protocol has to be followed strictly and the protocol settings
should be accurately validated. The unsatisfactory performance of
HercepTest in this run should be interpreted with care, as the
staining problems are based on only one tissue sample. New tests on
more 2+ carcinomas must be carried out. A discordance between cell
lines and tissues of 21% emphasizes that cell lines cannot be used
for quality assessment of HER-2 staining without tissue samples
included.
7 July 2008
Mogens Vyberg
Scheme manager |
