The American Cancer Society (ACS) recently published updated recommendations1 for the early detection of cervical cancer; this topic was last reviewed in 1987. The guidelines are based on a literature review combined with expert opinion when sufficient evidence was not available. In an effort to build consensus, several professional groups also were provided an opportunity to review and endorse these guidelines.
The ACS guidelines suggest a movement toward less excess screening and incorporation of emerging technologies when clinically feasible. The accompanying table on page 1678 compares the ACS guidelines with the U.S. Preventive Services Task Force (USPSTF) recommendations2 that appear in this issue of American Family Physician. The USPSTF strongly endorses the use of Papanicolaou (Pap) smears to detect premalignant and malignant lesions. It reaffirms cessation of screening at 65 years of age, recommends against Pap screening among women who have had hysterectomies for benign conditions, and in contrast with the ACS, concludes that there is insufficient evidence to assess the use of new technologies (e.g., thin-layer cytology, computerized screening, human papillomavirus [HPV] testing).
Advances in understanding the natural history of HPV infection and cervical cancer biology have revealed that HPV infections generally are transient. Among high-risk HPV subtypes, 70 percent of infections regress within two years,3 suggesting that less aggressive testing among younger women will allow for the spontaneous regression of HPV-associated abnormalities before screening is initiated.
The updated ACS guideline states that women over age 70 who have had three consecutive negative Pap tests over the prior 10 years may discontinue screening. As noted in the guideline, the decision mandates a discussion regarding the risks, benefits, and limitations of screening, as well as clinical judgment regarding other factors in a patient's medical history.
Although lacking in proven efficacy, vaginal cuff smears after hysterectomy for benign conditions appear to be a common clinical practice, accounting for untold medical costs and patient discomfort. The ACS guideline recommends against vaginal cytology testing after total hysterectomy for benign conditions when sufficient documentation is available. Women who have undergone a subtotal hysterectomy should continue standard cervical cancer screening. Patients with a history of cervical intraepithelial neoplasia grade 2 or 3 (CIN 2/3) and patients for whom it is not possible to document the absence of CIN 2/3 should be screened until three documented, consecutive, technically satisfactory normal/negative cervical cytology tests are achieved within 10 years.
|Criteria||USPSTF guideline||ACS guideline|
|Age to initiate screening||Optimum age unknown; within three years of onset of sexual activity or by age 21||Three years after the onset of sexual activity; no later than age 21|
|Screening frequency||At least every three years||Annually with conventional cytology or every two years with liquid-based cytology. After age 30, women with three consecutive normal tests may be screened every two to three years.|
|Screening after hysterectomy||No cytologic testing after total hysterectomy for benign condition||No cytologic testing after total hysterectomy for benign condition|
|Discontinuation of screening*||After age 65||After age 70|
|Routine screening for HPV infection||Insufficient evidence||Not yet approved by FDA. If approved, conventional cytology or liquid-based cytology combined with test for DNA from high-risk HPV subtypes should be performed not more often than every three years (preliminary recommendation)|
The ACS guideline also recommends that testing should be performed annually with conventional cervical cytology or every two years with liquid-based cytology, owing to the greater sensitivity of liquid-based tests. At or after age 30, women who have had three consecutive, technically satisfactory, normal/negative tests may be screened every two to three years unless there is a clinical contraindication to this approach. A history of normal/negative cytologic results has been shown to have a protective effect on cervical cancer incidence,4,5 probably as a result of the detection and treatment of various premalignant cervical lesions. Although many published studies examining liquid-based Pap technology appear to have some methodologic flaws, this test is an acceptable option for cervical cancer screening. Liquid-based Pap tests and conventional cytology yield similar percentages of satisfactory specimens.6
Although the U.S. Food and Drug Administration (FDA) has not approved HPV DNA testing for primary cervical cancer screening, this technology appears to be a promising adjunct to cytologic testing. The ACS guideline states that if the FDA approves HPV DNA testing (in combination with cytology) for cervical cancer screening, it is reasonable in women aged 30 years and older to perform cervical cancer screening every three years with conventional or liquid-based cytology in combination with a test for DNA from high-risk HPV subtypes. Combined cytology and HPV DNA testing should not be performed more often than every three years. Counseling and educating patients about the risks of HPV infection remains a priority. The recommendation to restrict HPV testing to women age 30 and older would reduce the number of women referred for colposcopy because of transient HPV infection.
The ACS guideline also provides relevant recommendations for collecting cervical specimens, including use of an extended-tip spatula to sample the ectocervix and the transformation zone and use of an endocervical brush (rather than a swab) to collect endocervical cells and high transformation zone specimens. Alternatively, a single sample device, such as the cervical broom, can be used to simultaneously sample the endocervix and transformation zone.
Family physicians are encouraged to fully review the ACS and USPSTF cervical cancer screening guidelines and to discuss techniques for liquid-based cytologic specimen collection with their local laboratory or cytologic pathologist. The American Academy of Family Physicians currently is evaluating its prevention recommendations and reviewing the literature on cervical cancer screening.
editor's note: Although the new ACS guidelines on cervical cancer screening are less stringent than the group's previous recommendations, they are more aggressive than the USPSTF guidelines, which, interestingly, have changed little from their 1996 version. Perhaps the most important change in both groups has been to relax the recommended age at which to initiate screening. Recognizing the slow progression of cervical cancer and the low yield of screening among adolescents, both groups recommend waiting up to three years from the onset of sexual activity to begin screening. The numeric minimum age safeguards against possible disease in patients who cannot or will not disclose their sexual history.
The ACS is more stringent than the USPSTF regarding subsequent screening intervals. The USPSTF holds that despite the different pathology of more aggressive HPV subtypes, more frequent testing adds only a slight overall benefit. Finally, because of the concern about false-positive screening results, the USPSTF refrains from making recommendations about the use of new technologies. Physicians who follow the USPSTF guidelines while remaining attentive to the clinical context will prevent cervical cancers in their patients. Many practitioners will choose to follow the more aggressive ACS guidelines, but at least these will reduce excessive screening.—Caroline Wellbery, M.D., Ph.D., assistant deputy editor of American Family Physician, Washington, D.C.