CHAPTER 4: SCREENING FOR CERVICAL CANCER

Chapter 4: Screening for Cervical Cancer 85• false positive test results (abnormalities reported in women whose cervix is normal),which may lead to unnecessary interventions and anxiety;• false negative test results (a normal screening test in women with cervicalabnormalities);• identification of other illnesses, for which treatment may not be available.Following the recommendations in this Guide will, in general, help to minimize theseundesirable outcomes.Target groups and frequency of screeningDecisions on the target age group and frequency of screening are usually made at thenational level, on the basis of local prevalence and incidence of cervical cancer, relatedfactors such as HIV prevalence, and availability of resources and infrastructure.All existing data on recommended ages and frequency of screening are derived fromexperience in cytology programmes. To date, there are no comparable data fromprogrammes using HPV-based and visual screening methods.When deciding on target age group and screening frequency, planners should take intoaccount the following:• HPV infection is very common in young women, but most infections are transient.• Only a small percentage of all HPV infections will lead to invasive cancer.• Cervical cancer usually develops slowly, taking 10–20 years from early precancer toinvasive cancer.• Cervical cancer is rare before the age of 30 years. Screening younger women willdetect many lesions that will never develop into cancer, will lead to considerableovertreatment, and is not cost-effective.• Screening every three years is nearly as effective as yearly screening. If resourcesare limited, screening every 5–10 years – or even just once between the ages of 35and 45 years – will significantly reduce deaths from cervical cancer.4Chapter 4: Screening for Cervical Cancer