Gross Evaluation of Breast Carcinomas Post-Neoadjuvant Chemotherapy Without Radio-opaque Clip Insertion: An Alternative Option.

Abstract

Gross evaluation of post-neoadjuvant chemotherapy breast carcinoma is challenging when the primary tumor is not localized before therapy with a radio-opaque wire/clip, a situation common in resource-constrained settings. To compare 2 grossing approaches in post-neoadjuvant chemotherapy breast carcinoma specimens to evaluate the sampling adequacy. Fifty breast carcinoma specimens were grossed in a 2-step manner. The tumor bed was identified using clinico-radiologic and gross correlation, and 1 slice was selected as the most representative (sample I). Subsequently, the entire tumor bed was submitted in grids of multiple slices (sample II). Agreement between methods was assessed using κ values. Sample I resulted in an average of 8 blocks per case, while sample II resulted in 26 blocks. Pathologic complete response (pCR) by both methods was calculated. Sample I documented 23 cases with pCR, of which 21 were confirmed by sample II. The 2 cases missed by sample I had less than 5% residual tumor (residual cancer burden class I). Both cases were human epidermal growth factor receptor 2 (HER2)-positive, and residual tumor was seen in the slices adjacent to the selected slice. The concordance between the 2 methods was 94%, with a κ value of 0.915 for sample I, indicating excellent correlation with sample II. The average cost of sample I was 33% of that of sample II and helped calculate the residual cancer burden with similar accuracy. However, in HER2-positive cases, pCR may be overestimated. Hence, we recommend sampling slices adjacent to the selected tumor slice. Further study using this method is essential due to its limited sample size and single-center design before considering implementation in the general population.