May 2010
PAP/NGC Programs Review

Roger B. Lane, MD

The American College of Obstetricians and Gynecologists has issued a practice bulletin on cervical cancer screening. The bulletin provides a review of the best available evidence on screening for cervical cancer to aid practitioners in making decisions about appropriate obstetric and gynecologic care (Cervical cytology screening. ACOG Practice Bulletin 109. American College of Obstetricians and Gynecologists. Obstet Gynecol. 2009;114:1409–1420). It replaces a bulletin issued in 2003 and ACOG committee opinions issued in 2004 and 2009.

The bulletin begins with a background review of cervical cancer screening, emphasizing that 50 percent of women in whom cervical cancer is diagnosed each year have never had cervical cytology testing and another 10 percent have not been screened within the five years before diagnosis. Thus, an important approach to reducing the incidence and mortality of cervical cancer is to increase screening rates for women who have not been screened or are screened infrequently.

The bulletin reviews errors in cervical cytology (sampling and interpretation errors and errors in followup) and the natural history of cervical neoplasia. It discusses briefly the human papillomavirus vaccine and its potential to reduce the incidence of cervical cancer. In addition, it compares and contrasts liquid-based and conventional methods of cervical cancer screening and reviews the 2001 Bethesda System classification.

The bulletin recommends that screening begin at age 21 regardless of age of onset of sexual intercourse, based on the high prevalence of HPV infection in women younger than 21, the high rate of spontaneous re-gression of infections, the rarity of cervical cancer in women younger than 21, and the potential for adverse side effects asso-ciated with treatment.

It addresses optimal screening frequency with a recommendation for screening every two years from age 21 to 29 and every three years in women age 30 and older who have had three consecutive negative cervical cytology test results and do not have risk factors for cervical dysplasia. More frequent screening may be required for women with risk factors, it says, including HIV infection, immunosuppression, history of diethyl-stilbestrol exposure in utero, and history of previous treatment for high-grade squamous intraepithelial lesion or cancer. In particular, the recommendation for women with HIV infection is for screening twice in the first year after diagnosis and annually thereafter. For women with a history of HGSIL or cancer, annual screening is recommended for at least 20 years. A detailed discussion of literature supporting less than an-nual screening and a cost-effectiveness data analysis are provided. In addition, the bulletin discusses appropriate ages for discontinuing screening and when screening may be discontinued in women who have had a hysterectomy.

The bulletin summarizes the appropriate use of HPV testing, including its use as a triage test to stratify risk in women 21 and older with ASC-US and in postmenopausal women with a cytology diagnosis of low-grade squamous intraepithelial lesion. The bulletin says co-testing using a combination of HPV testing and cytology is an appropriate screening test for women older than 30 years; any low-risk woman 30 years of age or older who receives negative test results on both cervical cytology screening and HPV DNA testing should be rescreened no sooner than three years subsequently. HPV testing may also be used as a followup test after CIN 1 or negative findings on colposcopy in women whose prior cytology diagnosis is ASC-US, ASC-H, LSIL, or atypical glandular cells, and in followup after treatment for CIN 2 and CIN 3. HPV testing should not be used in females younger than 21 years, and, if inadvertently performed, a positive result should not influence management.

As technology and recommendations for cervical cancer screening continue to evolve rapidly, this bulletin will be useful to practicing obstetricians and gynecologists and is recommended reading for all involved in cervical cancer cytology screening.