The fraction of fields showing neoplastic tubules: a practical estimate oftubular differentiation in breast cancer

Aims: The purpose of the study is to evaluate histological measurement meth ods for quantitative assessment of the degree of tubular differentiation in breast cancer. Methods and results: We evaluated tubular differentiation in 20 cases of in vasive breast cancer by four different assessment methods. Method 1 was the traditional subjective evaluation of the amount of malignant tubules in ea ch sample. Method 2 evaluated the fraction of fields presenting tubular dif ferentiation by registering the presence or absence of neoplastic tubular s tructures in each microscopic field, In method 3 the area fraction of malig nant epithelial cells presenting tubular differentiation was assessed field -by-field and expressed as an average of the whole tumour area, Method 4 ap plied point counting for evaluating the fraction of malignant epithelial ce lls in tubular structures. By correlation and reproducibility analyses, met hod 1 was inferior to the other methods. Method 4 was accurate but too labo rious and time-consuming for clinical use. Methods 2 and 3 were both effici ent and reproducible and could be used interchangeably With the time and ef fort used in the measurements taken into consideration method 2 was best ap plicable to clinical practice. Conclusion: Accurate evaluation of tubular differentiation in breast cancer is possible by defining the presence or absence of tubular differentiation in microscopic fields of a histological section. Assessment of the fractio n of fields with tubular differentiation (FTD) is simple, unambiguous, obje ctive and fast - even a large sample can be screened in less than 10 min. I n our results, FTD has clear advantages over subjective or point counting-b ased evaluation methods of tubular differentiation.