Fig. 1.

Natural History of Cervical Cancer for Squamous and Glandular Pathways, Distribution of Study Population at Baseline.

Fig. 1 depicts the natural history of cervical cancer in 2 separate pathways for squamous cell carcinoma (SCC) and adenocarcinoma (AC). The majority of the population (91%) has a normal cervix (no HPV infection) with negative HPV result in a screening population. The most common abnormality on the pathway to cervical cancer is HPV-positive NILM. Earlier more minor abnormality for SCC is ASC-US/LSIL which is more common than its equivalent on the AC path, AGC NOS (NOS: not otherwise specified). Even though AGC is a diverse cytologic category (therefore not being a direct counterpart of ASC-US/LSIL), it is the only known early minor precursor for AC and AGC NOS is more minor abnormality compared to AGC favor neoplasia (FN). At the precancer stage, cytologic high-grade abnormalities ASC-H/HSIL and histologic abnormalities, CIN3, are well-defined for the SCC pathway. However, AGC FN and adenocarcinoma in situ (AIS) are the only known immediate precursors for AC and these abnormalities are very uncommon and mostly underdiagnosed. Adenosquamous cases are grouped with AC in our study which is a very small percentage of the whole population. There is also crossover between the two pathways, which is represented with faded crossing arrows at the end of the fig. (10% of the AC/AIS cases are followed by HSIL cytology among HPV positives).