The evaluation of tubule formation in breast cancer using fraction of fields showing tubular differentiation (FTD) method and compare it with conventional methods

Histological grading is one of the most important prognostic factors in breast cancer. So far, there has not been any available method for quantitative estimation of tubular differentiation. Therefore, this study was aimed to evaluate the experimental and conventional method and compare the reproducibility of it with the other quantitative and semi-quantitative methods using 200 morphometric microscopic magnifications. In this descriptive-analytical study which, conducted in 2006, a total of 38 histological samples of breast invasive ductal carcinoma were selected and tubular differentiation was assessed by two pathologists using three methods. The first method (conventional), the rate of tubular differentiation (a portion of tumor with malignant tubules) to the total sample calculated and shown in percentage. The second one, was the fraction of fields showing tubular differentiation (FTD), and the third one was the subjective evaluation of each field and then considering the mean of all fields. Using Friedman test, the difference between the 3 methods was compared and Kappa test was used to compare the reproducibility of each method between the two observers. The results showed that using the second method, the scoring of the samples by the two observers was almost the same. It means that Kappa indices in the first, second, and third method was 0.4, 0.832, and 0.558, respectively (p<0.001). Also, Friedman test showed that there was statistically significant difference between the findings of each of the observers in any of the 3 methods used (p<0.001). Base on the results, FTD has higher reproducibility than that of other two methods. Thus, it can be used as a simple method in assessment of tubular differentiation.