Effect of freezing on histologic grading of invasive ductal breast cancer.
OBJECTIVE
To quantify the histologic changes caused by freezing during tissue processing and their influence on histologic malignancy grading as a prognostic factor in invasive ductal breast cancer.


METHODS
We studied frozen and nonfrozen formalin-fixed, paraffin-embedded samples of 18 cases of invasive ductal breast cancer. Features associated with histologic malignancy grading of breast cancer--i.e., nuclear pleomorphism, mitotic index and tubular differentiation--were assessed by quantitative morphometric methods.


RESULTS
In our material, frozen samples consistently had a smaller mean nuclear profile area than nonfrozen samples (mean difference, 32%). Frozen nuclei were also clearly less symmetric and uniform in shape than non-frozen nuclei. Moreover, frozen samples had consistently higher mitotic indices than nonfrozen samples (mean difference, 66%, with the standardized mitotic index). Tubular differentiation, as expressed in fraction of fields with tubular differentiation, increased by 16% as a result of sample freezing.


CONCLUSIONS
According to our results of morphometric measurement in invasive ductal breast cancer, great caution should be exercised when prognostic conclusions are based on frozen tissue samples.
Kronqvist
Pauliina
P
Department of Pathology, University of Turku, Kiinamyllynkatu 10, SF-20520 Turku, Finland.
Kuopio
Teijo
T
Collan
Yrjö
Y
D016477:Artifacts; D001943:Breast Neoplasms / Q000175:diagnosis*; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis*; D002467:Cell Nucleus / Q000473:pathology; D015925:Cryopreservation; D005260:Female; D005615:Freezing; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008940:Mitotic Index; D011237:Predictive Value of Tests; D011379:Prognosis; D013048:Specimen Handling / Q000379:methods*