Tumor Budding in Invasive Breast Carcinoma, No Special Type: Association With Pathological Prognostic Factors and Comparison of 2 Different Scoring Systems.

Introduction. In contrast to colorectal carcinoma, the significance of tumor budding in breast carcinoma is not established. The X20 objective which is used to assess tumor budding in colorectal carcinoma, is not widely available in countries with limited resources. This study aimed to determine the prevalence of tumor budding and its associations with pathological prognostic factors in invasive breast carcinoma-no special type (IBC-NST), and to assess the correlation between the tumor budding observed using ×20 and ×40 objectives. Methods. A total of 349 excision specimens of IBC-NST were studied. Tumor budding was defined as a single cell/cluster of up to 4 cells at the invasive front and was assessed in hotspots at the advancing edge of the tumor using ×20 and ×40 objectives. Tumor budding was categorized into low (<5/0.785 mm²), intermediate (5-9/0.785 mm²), and high budding (≥10/0.785 mm²) for ×20 objective and low (≤4/0.196 mm²) and high (≥5/0.196 mm²) for ×40 objective based on the number of buds per hotspot. The association between tumor budding and prognostic factors was analyzed with Mann-Whitney U test, Kruskal-Wallis test, χ² test, and logistic regression. Correlation between tumor budding in ×20 and ×40 objectives was analyzed with Pearson correlation test. Results. The prevalence of tumor budding was 72.5%. There was a significant correlation between the number of buddings observed in ×40 objective and ×20 objective (0.958). High tumor budding observed in both objectives was significantly associated with size (P < .001), lymphovascular invasion (P < .001), perineural invasion (P < .001), lymph node status (P < .001), number of lymph nodes (P < .001), T stage (P < .001), and N stage (P < .001) on univariate analysis, but only lymph node positivity (P < .001) showed significant association on multivariate analysis. Conclusion. Tumor budding assessed with ×20 and ×40 objectives showed a significant correlation and was significantly associated lymph node metastasis on multivariate analysis.