Reproducibility of subjective immunoscoring of steroid receptors in breast cancer.
OBJECTIVE
To evaluate the reproducibility of subjective immunoscoring of steroid receptors in breast cancer by inexperienced observers after brief training by one experienced observer.


METHODS
Thirteen inexperienced observers were trained for a few minutes semiquantitatively (0-4) to score tumor nuclei in two breast cancer frozen sections immunohistochemically stained each for estrogen or progesterone receptors. Then, the fractions of 0, 1, 2, 3 and 4 "stained" nuclei were estimated individually. Thereafter, the experienced observer pointed out the nuclei one by one, and the participants scored these nuclei individually. From these data, histoscores were calculated.


RESULTS
When comparing individual scorings (n = 1,320) with the gold standard, discrepancies occurred mainly between scores 2 and 3, and the best concordance was achieved for the scores 0 and 4. For the histoscores, coefficients of variations for the estimated scores (7.3-33.7, mean 17.2) were systematically higher than those derived from nucleus-by-nucleus scoring (2.6-15.4, mean 10.3).


CONCLUSIONS
Inexperienced observers can be trained quickly to arrive at fairly reproducible histoscores for immunohistochemically stained estrogen and progesterone receptors in breast cancer frozen sections. Nucleus-by-nucleus scoring seems to be more reproducible than estimating fractions of nuclei with certain positivity and should be recommended in cases of values close to the decision threshold.
Department of Pathology, Free University Hospital, Amsterdam, The Netherlands.
P J
PJ
van Diest
D R
DR
Weger
J
J
Lindholm
D001943:Breast Neoplasms / Q000737:chemistry*; D007150:Immunohistochemistry / Q000379:methods*; D015588:Observer Variation; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D015203:Reproducibility of Results
D011960:Receptors, Estrogen; D011980:Receptors, Progesterone