Role of micronucleus scoring in buccal smears of carcinoma breast cases - A study in rural central India

Background: Micronucleus (MN), a small additional nucleus represents a sensitive indicator of chromosomal damage. It can be detected in buccal cells with the use of Giemsa stain by light microscopy and acridine orange (AO) stain by fluorescent microscopy. Objective: The aim of this study was to analyze the MN score in buccal smears of infiltrating duct carcinoma (IDC) cases and fibroadenoma (FA) cases as a control group. Materials and Methods: It was a prospective observational study, which included 78 IDC cases and 82 FA cases (as controls). The Giemsa and AO stained buccal smears were analyzed, and MN scoring was compared between IDC and FA cases. Results: The mean MN score of FA and IDC was 0.10 ± 0.31 and 1.97 ± 0.73 in AO and 0.10 ± 0.31 and 1.58 ± 0.74 in Giemsa stained smears (P = 0.0001 and 0.0003) respectively. The MN score increased in a stepwise manner from Grade I to II, II to III of IDC in Giemsa-stained smears. The comparison between FA and three different grades of the IDC (P< 0.001 each) and mean MN score between Grade II and III IDC (P = 0.007) was statistically significant. While the comparison of mean MN score between Grade I and Grade II IDC was not statistically significant (P = 0.940). The mean MN score with AO stain was higher than the mean MN score with Giemsa, and this difference was statistically significant (P = 0.001). Conclusions: MN scoring in buccal smears in IDC cases was significantly increased than in FA cases. MN assay in buccal smears of a breast lump can be used as a potential biomarker for screening for breast carcinoma as it represents generalized chromosomal damage.