Before the epidemiology and molecular biology of cervical neoplasia were well established, cervical cancer screening was based on cytology alone. Cytology served as the basis for referral to colopscopy and colposcopic biopsy was the basis for therapeutic management, This morphology based system, repeated systematically effected a 75-90% reduction in cancer and precancer prevalence. Yet this apporach has established limitations. The objective of this presentation is to review the contemporary risk estimates for CIN3+ of the major Bethesda categories and then to also provide similar estimates for the corresponding biopsy interpretations.
Morphologic images wiill be correlated with risk estimates based on the ALTS trial and contremporary epidemiologic literature. The error rates based on sampling issues and intepretivevvariability will also be explored based on literature data.
The squamous cytologic categories of the TBS can be hierarchically ranked for CIN3+ risk in the order NILM>ASC-US>LSIL>ASC-H>HSIL. AGC associated risk is roughly the same as ASC-H and paradoxically mostly predicts for squamous leisons. HPV genotyping may modify risk substantially between categories. Intepretive variability is signifcant for both cytology (ASC-US) and Histology (CIN1 and CIN2). Sampling variability also confounds predictive value. These factor combine to prove that histology is not necessarily a superior predictor of biology compared to cytology.
Despite cytology and histology having established outstanding success in decreasing cervical cancer: A. Sampling issues and interpretive variability are highly confounding. B. Compensatory strategies that combine HPV molecular testing , biomarkers and better sampling methods are increasingly available. C. As prevalence decreases due to increased screening and vaccination these compensatory strategies will become increrasingly necessary.