TAKE-HOME POINTS■ Age of initial screening is 21 years for all women. Screening intervals are every 2 years for women aged 21 to 29 years and every 3 years for women aged 30 to 70 years who have had three consecutive negative results on liquid-based cytology. Discontinuation of screening is suggested for women aged 65 to 70 years who have had 3 or more consecutive negative results on cytology and no abnormal results within the preceding 10 years.
■ Women who have HIV or are immunocompromised, were exposed to diethylstilbestrol in utero, or have a
history of cervical cancer should be screened more frequently.
■ Women who received the HPV vaccine should be screened following the same protocol used for unvaccinated women.
WHO SHOULD READ THIS?
All PAs who participate in preventive health education, provide women's health care, or educate patients on cancer screening should have knowledge of the most recent guidelines.
WHY IS THIS IMPORTANT?
Over the past 30 years, the number of cervical cancers detected has declined by 50%.1 According to the American Cancer Society, approximately 11,270 women in the United States received a new diagnosis of cervical cancer in 2009, with an estimate of 4,070 deaths. The majority of these fatalities were attributed to inadequate screening.1-3 Sirovich and colleagues stated that, in the United States, "cases of invasive cervical cancer are more likely to represent failure to perform appropriate screening than inaccuracies of screening when performed. More than half of women who develop cervical cancer never had cervical cytology, were screened sporadically, or were not screened within the previous five years."3
In November 2009, the American College of Obstetricians and Gynecologists (ACOG) modified the cervical cancer screening guidelines. The goal was to minimize anxiety and expenses related to additional or unneeded testing in adolescents with an abnormal test result while continuing to maximize patient health and outcomes. Adolescents with abnormal test results usually show a spontaneous regression of the lesion(s) and do not require additional procedures. Surveillance Epidemiology and End Results 2002-2006 data show that females aged 15 to 19 years have an incidence of cervical cancer of one to two cases per million screened.3 ACOG states that clinicians should avoid procedures that could affect the cervix and potentially cause problems with childbearing in that population.1
The single largest cause of cervical cancer is infection with certain strains of the human papillomavirus (HPV).1 In a Canadian cervical cancer screening trial that involved more than 10,000 women, HPV testing had better specificity in women 30 years and older, and sensitivity in detecting cervical intraepithelial neoplasia (CIN) 2 or CIN3 was higher.3 Even though DNA testing for HPV has been available since 2003, it was not incorporated into the ACOG guidelines. The Cytopathology Education and Technology Consortium developed recommendations for HPV testing based on guidelines from the American Society for Colposcopy and Cervical Pathology and the ACS (Table: CETC HPV screening recommendations in the online version of this article).
Seventy percent of cervical cancer risk is directly related to persistent infection with two strains of HPV: 16 and 18.4 Two HPV vaccines are currently available for females aged 9 to 26 years. The bivalent vaccine protects against types 16 and 18 and the quadrivalent protects against types 6, 11, 16, and 18. Continued screening is needed to identify the other 30% of oncogenic HPV types for which the vaccine provides no protection. Some health care providers are evaluating the use of HPV-DNA testing to screen for vaccine failures and to increase the time between screening tests.5
WHAT IS THE CURRENT SCREENING METHOD?
ACOG suggests using the Pap smear or liquid-based cytology. Both methods involve obtaining cells from the squamocolumnar junction, which is the transformation zone or border between the cervical epithelium and the cervical columnar epithelium. For the Pap smear, the cells are placed on a slide and fixed with an alcohol-containing fixative. For liquid-based cytology, the cells are placed in a liquid fixative solution; loose cervical cells are then plated in a monolayer on glass slides. A pathologist examines the specimen for any abnormalities in the cellular characteristics.6