How predictive is a cervical smear suggesting invasive squamous cell carcinoma?

How predictive is a cervical smear suggesting invasive squamous cell carcinoma? Features have been described in severely dyskaryotic cervical smears that suggest frankly invasive or microinvasive squamous cell carcinoma. These are reported in three separate categories in our department. The aim of the current study was to assess the positive predictive value of these categories for invasive disease on histology. All smears reported in these categories over a five year period were correlated with the histology results. 527 smears were assessed. The positive predictive value of a smear suggesting frank invasion was 55.7% for all invasive squamous carcinomas and 40% for stage IB or above. Smears suspicious of invasion or microinvasion predicted invasive disease in 22.3% and 17.2%, respectively, most carcinomas being stage IA. Invasive squamous cell carcinoma may be predicted to a limited degree by cervical cytology especially when the smear suggests frank invasion.