Significance of micronucleus in cervical intraepithelial lesions and carcinoma

BACKGROUND: The micronuclei (MNi) test on exfoliated cells has been successfully used to screen population groups at risk for cancers of oral cavity, urinary bladder, cervix and esophagus. Their frequency appears to increase in carcinogen-exposed tissues long before any clinical symptoms are evident. There are only limited numbers of studies on MN scoring in cervical pre-neoplastic and neoplastic conditions. AIMS: To compare the micronucleus (MN) score in the whole spectrum of cervical lesions including normal, inflammatory, abnormal squamous cells of undetermined significance (ASC-US), abnormal squamous cells cannot exclude HSIL (ASC-H), low-grade squamous intraepithelial lesion (LSIL), high-grade squamous intraepithelial lesion (HSIL) and invasive cancer (IC) and to evaluate the role of MN as a biomarker in different pre-neoplastic and neoplastic lesions. MATERIALS AND METHODS: A total of 221 slides, comprised of normal (32), inflammatory (32), ASC-US (31), ASC-H (31), LSIL (32), HSIL (31) and IC (32), were studied. All the cases were reviewed by two pathologists independently. Histopathological correlation was done in a few cases of ASC-US, ASC-H, HSIL and IC which were available in the department. Two observers separately and independently counted the number of micronucleated cells per 1,000 epithelial cells in oil immersion magnification and were expressed as MN score per 1,000 cells. RESULTS: The mean MN scores ± SD in normal, inflammatory, ASC-US, ASC-H, LSIL, HSIL and IC cases of cervical lesions were 0.84±0.68, 1.06±0.84, 3±0.73, 4.78±1.43, 4.06±1.13, 8.03±1.64 and 10.5±2.01, respectively. MN scores of IC and HSIL were significantly high compared to normal (P<0.000), inflammatory (P<0.000), ASC-US (P<0.000), ASC-H (P<0.000) and LSIL (P<0.000) group (analysis of variance test). LSIL showed significant difference with the normal (P<0.000), inflammatory (P=0.001), ASC-US (P=0.028), HSIL (P<0.000) and IC (<0.000), but not with the ASC-H (P=0.64) group. CONCLUSIONS: MN scoring on the epithelial cells of cervix could be used as a biomarker in cancer screening. This is an easy, simple, reliable, reproducible and objective test which can be performed on routinely stained pap smears.