Positive correlation between the frequency of micronucleated cells and dysplasia in Papanicolaou smears

Most cancers arise in epithelial tissues and these tissues are typically the targets of the carcinogens responsible for the tumors. Exfoliated epithelial cells have traditionally been used for cancer screening by cytopathologists and these cells also can be used for biomonitoring of genotoxic effects in humans. Cervical cancer results from the progression of preinvasive precursor lesions, called low-grade squamous intraepithelial lesions (LGSILs), to high-grade squamous intraepithelial lesions (HGSILs). The gradient from low to high-grade lesions is characterized by increasing nuclear atypia and the failure of cellular differentiation in progressively more superficial levels of the epithelium. These phenotypic changes are hypothesized to be accompanied by increased genetic instability that can be documented using the micronucleus (MN) assay in exfoliated cervical cells. A retrospective study was performed to investigate the frequency of micronucleated cells in cervical smears from women at high risk for developing cervical cancer. Papanicolaou (Pap) smears from 275 women previously studied at a cancer clinic were coded and analyzed for the frequency of micronucleated cells. LGSIL, HGSIL, and invasive carcinoma smears had significantly higher frequencies than normal and ASCUS (abnormal squamous cells of undetermined origin) smears. HGSIL or severely dysplastic smears had the highest frequency of micronucleated cells (although not significantly higher than LGSIL smears), an observation that that could be useful in confirming these types of lesions. The results indicate that the MN frequency in exfoliated cervical cells may be an additional criterion for establishing cervical cancer risk.