The U.S. Preventive Services Task Force (USPSTF) grades its recommendations (A, B, C, D, or I) and the quality of the overall evidence for a service (good, fair, poor). The definitions of these grades can be found at the end of the "Major Recommendations" field.
- The U.S. Preventive Services Task Force (USPSTF) strongly recommends screening for cervical cancer in women who have been sexually active and have a cervix. A recommendation.
The USPSTF found good evidence from multiple observational studies that screening with cervical cytology (Papanicolaou [Pap] smears) reduces incidence of and mortality from cervical cancer. Direct evidence to determine the optimal starting and stopping age and interval for screening is limited. Indirect evidence suggests most of the benefit can be obtained by beginning screening within 3 years of onset of sexual activity or age 21 (whichever comes first) and screening at least every 3 years (see Clinical Considerations below). The USPSTF concludes that the benefits of screening
substantially outweigh potential harms.
- The USPSTF recommends against routinely screening women older than age 65 for cervical cancer if they have had adequate recent screening with normal Pap smears and are not otherwise at high risk for cervical cancer (see Clinical Considerations below). D recommendation.
The USPSTF found limited evidence to determine the benefits of continued screening in women older than 65. The yield of screening is low in previously screened women older than 65 due to the declining incidence of high-grade cervical lesions after middle age. There is fair evidence that screening women older than 65 is associated with an increased risk for potential harms, including false-positive results and invasive procedures. The USPSTF concludes that the potential harms of screening are likely to exceed benefits among older women who have had normal results previously and who are not otherwise at high risk for cervical cancer.
- The USPSTF recommends against routine Pap smear screening in women who have had a total hysterectomy for benign disease. D recommendation.
The USPSTF found fair evidence that the yield of cytologic screening is very low in women after hysterectomy and poor evidence that screening to detect vaginal cancer improves health outcomes. The USPSTF concludes that potential harms of continued screening after hysterectomy are likely to exceed benefits.
- The USPSTF concludes that the evidence is insufficient to recommend for or against the routine use of new technologies to screen for cervical cancer. I recommendation.
The USPSTF found poor evidence to determine whether new technologies, such as liquid-based cytology, computerized rescreening, and algorithm based screening, are more effective than conventional Pap smear screening in reducing incidence of or mortality from invasive cervical cancer. Evidence to determine both sensitivity and specificity of new screening technologies is limited. As a result, the USPSTF concludes that it cannot determine whether the potential benefits of new screening devices relative to conventional Pap tests are sufficient to justify a possible increase in potential harms or costs.
- The USPSTF concludes that the evidence is insufficient to recommend for or against the routine use of human papillomavirus (HPV) testing as a primary screening test for cervical cancer. I recommendation.
The USPSTF found poor evidence to determine the benefits and potential harms of HPV screening as an adjunct or alternative to regular Pap smear screening. Trials are underway that should soon clarify the role of HPV testing in cervical cancer screening.
Clinical Considerations
- The goal of cytologic screening is to sample the
transformation zone, the area where physiologic transformation from columnar
endocervical epithelium to squamous (ectocervical) epithelium takes place and
where dysplasia and cancer arise. A meta-analysis of randomized trials
supports the combined use of an extended tip spatula to sample the ectocervix
and a cytobrush to sample the endocervix.
- The optimal age to begin screening is unknown. Data
on natural history of human papillomavirus (HPV) infection and the incidence of high-grade lesions and cervical cancer suggest that screening can safely be delayed until 3 years
after onset of sexual activity or until age 21, whichever comes first.
Although there is little value in screening women who have never been sexually
active, many U.S. organizations recommend routine screening by age 18 or 21
for all women, based on the generally high prevalence of sexual activity by
that age in the U.S. and concerns that clinicians may not always obtain
accurate sexual histories.
- Discontinuation of cervical cancer screening in older
women is appropriate, provided women have had adequate recent screening with
normal Pap results. The optimal age to discontinue screening is not clear, but
risk of cervical cancer and yield of screening decline steadily through middle
age. The USPSTF found evidence that yield of screening was low in previously
screened women after age 65. New American Cancer Society (ACS) recommendations
suggest stopping cervical cancer screening at age 70. Screening is recommended
in older women who have not been previously screened, when information about
previous screening is unavailable, or when screening is unlikely to have
occurred in the past (e.g., among women from countries without screening
programs). Evidence is limited to define "adequate recent screening." The ACS
guidelines recommend that older women who have had three or more documented,
consecutive, technically satisfactory normal/negative cervical cytology tests,
and who have had no abnormal/positive cytology tests within the last 10 years,
can safely stop screening.
- The USPSTF found no direct evidence that annual screening achieves better outcomes than screening every 3 years. Modeling studies suggest little added benefit of more frequent screening for most women. The majority of cervical cancers in the U.S. occur in women who have never been screened or who have not been screened within the past 5 years; additional cases occur in women who do not receive appropriate follow-up after an abnormal Pap smear. Because sensitivity of a single Pap test for high-grade lesions may only be 60% to 80%, however, most organizations in the U.S. recommend that annual Pap smears be performed until a specified number (usually 2 or 3) are cytologically normal before lengthening the screening interval. The ACS guidelines suggest waiting until age 30 before lengthening the screening interval; the American College of Obstetricians and Gynecologists (ACOG) identifies additional risk factors that might justify annual screening, including a history of cervical neoplasia, infection with HPV or other sexually transmitted diseases (STDs), or high-risk sexual behavior, but data are limited to determine the benefits of these strategies.
- Discontinuation of cytological screening after total hysterectomy
for benign disease (e.g., no evidence of cervical neoplasia or cancer)
is appropriate given the low yield of screening and the potential harms
from false-positive results in this population. Clinicians should confirm
that a total hysterectomy was performed (through surgical records or inspecting
for absence of a cervix); screening may be appropriate when the indications
for hysterectomy are uncertain. ACS and ACOG recommend continuing cytologic
screening after hysterectomy for women with a history of invasive cervical
cancer or diethylstilbestrol (DES) exposure due to increased risk for vaginal neoplasms,
but data on the yield of such screening are sparse.
- A majority of cases of invasive cervical cancer occur
in women who are not adequately screened. Clinicians, hospitals, and health
plans should develop systems to identify and screen the subgroup of women who
have had no screening or who have had inadequate past screening.
- Newer Food and Drug Administration (FDA)-approved technologies, such as liquid-based cytology (e.g., ThinPrep®), may have improved sensitivity over conventional Pap smear screening, but at a considerably higher cost and possibly with lower specificity. Even if sensitivity is improved, modeling studies suggest these methods are not likely to be cost-effective unless used with screening intervals of 3 years or longer. Liquid-based cytology permits testing of specimens for HPV, which may be useful in guiding management of women whose Pap smear reveals atypical squamous cells. HPV DNA testing for primary cervical cancer screening has not been approved by the FDA and its role in screening remains uncertain.
USPSTF grades its recommendations according to one of 5 classifications (A, B, C, D, I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms).
A
The USPSTF strongly recommends that clinicians provide [the service] to eligible patients. The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms.
B
The USPSTF recommends that clinicians provide [this service] to eligible patients. The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms.
C
The USPSTF makes no recommendation for or against routine provision of [the service]. The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes
that the balance of benefits and harms is too close to justify a general recommendation.
D
The USPSTF recommends against routinely providing [the service] to asymptomatic patients. The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh
benefits.
I
The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service]. Evidence that [the service] is effective is lacking, of poor quality, or conflicting and the balance of benefits and harms cannot be determined.
The U.S. Preventive Services Task Force (USPSTF) grades the quality of the overall evidence for a service on a 3-point scale (good, fair, poor).
Good
Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health outcomes.
Fair
Evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number,
quality, or consistency of the individual studies, generalizability to routine practice, or indirect nature of the evidence on health outcomes.
Poor
Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of
information on important health outcomes.
