Table 2.

Characteristics that make cervical cancer uniquely preventable.

Characteristic	Comment
A.Single etiologic agent	Approximately 13 HPV types cause virtually all cervical cancer worldwide. There are no other cancers for which there is a single, identifiable causal agent.
B.Slow-growing cancer	Average sojourn time from HPV exposure (initiation) to cancer is ~25 years.
C.Tissue accessibility	The cervix can be sampled directly by a brush for cytology and molecular testing for screening and by biopsy forceps to collect tissue for diagnosis with an outpatient speculum exam. The relative acceptability of sampling from this tissue allowed the early development of Pap testing, which was key to elucidating the natural history of cervical cancer, including the identification of a good surrogate (see D). Cervicovaginal sampling collects sufficient amounts of HPV for detection that self-collection is feasible.
D.Small area of susceptibility	The vast majority of HPV-related genital cancers occur in a very small annulus of tissue, the cervical transformation zone, with the most distal (from the vaginal opening) boundary defined by the squamocolumnar junction, which can be visualized, making sampling and diagnostic biopsies much simpler.
E.Proven surrogate for cancer	CIN3/AIS have some characteristics of invasive cervical cancer, most notably an HPV-type distribution. A proven surrogate permitted the more rapid validation of novel, HPV-targeted intervention strategies including HPV vaccination and HPV testing-based screening.