Evidence that supports policies to delay cervical screening until after age 25 years

Abstract

New guidelines for cervical screening from Alberta 1 and British Columbia 2 recommend increasing the starting age from 21 to 25 years. These guidelines follow the recommendations published by the Canadian Task Force on Preventative Health Care in 2013, 3 and are similar to many other highincome countries. Cervical cancer mostly has a long natural history and, consequently, is uncommon in women under age 25 years. Cervical screening among this age group has minimal impact on rates of carcinoma but does lead to overdiagnosis and overtreatment of precancerous lesions that are destined to regress or not progress to cancer until later. Physicians may be concerned that delaying screening for cervical cancer will lead to reduced testing for sexually transmitted infection and too few pelvic examinations. However, delaying the onset of cervical screening for women at average risk until after age 25 years strikes the best balance between screening benefits and substantial harms. We summarize the evidence on lead time to the development of invasive cervical cancer, incidence of cervical precancerous lesions and invasive cancer in young women, and harms of screening in young women, which has informed policies to delay the age at which cervical screening begins.Cervical cancer is caused by high-risk human papillomavirus (HPV) infection in susceptible women who do not clear it. Persistent infection may develop into precancer, and for a small proportion of patients, invasive cervical cancer. According to multiple epidemiologic studies, before screening, incidence of cervical cancer among unscreened populations was high from 35 to 65 years, which suggests a long lead-time from initial HPV infection at some time after the onset of sexual activity to the development of invasive cancer. 4,5 There are few studies of the untreated natural history, but a cohort study in New Zealand found that invasive cancer developed in 30% of women with carcinoma in situ (cervical intraepithelial neoplasia 3) over 30 years of follow-up. 6 Invasive cancer of the cervix is uncommon among women under age 25 years, regardless of screening practices. In Canada, the incidence among young women between 15 and 19 years of age has not changed since the era before widespread screening began in 1971: three per million.5 Among women between 20 and 24 years of age, incidence decreased from 3.2 to 1.2 per 100 000, with no change in uncommon mortality from invasive cervical cancer despite programs of annual screening, a pattern that reflects what has been observed in other high-income countries. 5On the other hand, abnormal screening results and precancerous cervical lesions are commonly observed in younger women. Rates of abnormal pap tests among women 20 to 24 years of age vary from 7.3% in British Columbia 7 to 23% in Newfoundland and Labrador.8 Most abnormalities are low grade and represent transient HPV infections that regress without intervention: few progress to high-grade precancer. A study in California involving 95 women under the age of 24 years with a...

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“…However, targeting women aged 25 years and above has both screening benefits and reduced harms due to overtreatment. 11 …”

“…In the current study, we included studies with women who are 25 years and older because HPV screening among women less than 25 years leads to overdiagnosis and overtreatment. However, targeting women aged 25 years and above has both screening benefits and reduced harms due to overtreatment 11…”

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“…It is believed that the majority of dysplastic cervical lesions, which are common in this age group have a tendency to regress spontaneously [21]. Therefore, covering this age group with screening may lead to overdiagnosis and subsequently -overtreatment of precancerous lesions [24]. However, Nygård et al [20] showed that women who perform Pap smear frequently have a tendency to follow this pattern, whereas those who do it seldomly or never, have no tendency to participate in screening in the near future.…”

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“…The trial personnel often performed cervical screening together with colposcopy every 6 months, and the included participants were often women aged 15-26. In clinical practice, cervical screening is usually performed every 3 to 5 years and recommended after age 25 [44], as most CIN2 + lesions in women under age 30 regress spontaneously, which may justify active surveillance rather than immediate intervention [45].…”