Screening for cervical cancer.

Indirect evidence indicates that cervical cancer screening should reduce the incidence and mortality of invasive cervical cancer by about 90%. In the absence of screening, a 20-year-old average-risk woman has about a 250 in 10,000 chance of developing invasive cervical cancer during the rest of her life, and about a 118 in 10,000 chance of dying from it. Screening at least every 3 years from 20 to 75 years of age will decrease these probabilities by about 215 in 10,000 and 107 in 10,000, respectively, and will increase a 20-year-old woman's life expectancy by about 96 days. The particular age at which screening is begun (for example, 17 or 20 years), the requirement of several initial annual examinations before reducing the frequency, and screening every 1 or 2 years compared with every 3 years improves the effectiveness by less than 5%. Screening is recommended at least every 3 years from about age 20 to about age 65 years.