Structured Abstract
Screening for Cervical Cancer
Prepared by Brenda J. Morrison, PhD, Associate
Professor, Department of Health Care and Epidemiology,
University of British Columbia, Vancouver,
BC
These recommendations were finalized by the Task Force in January 1992
Contents
Objective
To make recommendations about routine screening for cervical cancer among
asymptomatic women in Canada. This updates the 1979 Canadian Task Force
recommendations.
Burden
of Suffering
Cervical cancer is the eleventh most common cancer among women in Canada.
In 1993, an estimated 1,300 women developed cervical cancer and about 400
died of the disease. In 1989, an estimated 10,000 potential years of life
were lost due to cervical cancer. The major factors known to be associated
with the occurrence of cervical cancer are age of first sexual intercourse,
number of consorts, number of previous partners of consorts, smoking, low
socio-economic status and possibly infections such as human papillomavirus.
Most studies show that for each additional partner the risk appears to
increase linearly by a factor ranging from 0.5 to 1, up to a relative risk
of at least 9; for early age of first intercourse (before 17 or 18 years
of age), the relative risk has been reported to range between 2 and 3.
Depending upon the stage at which the disease is detected, five-year
survival rates range from 90% for stage 1 to 10-15% for stage 4, suggesting
that any screening measure which permits earlier detection will improve
survival.
Options
To screen or not to screen using the Papanicolaou smear test.
Outcomes
Papanicolaou test false negative error rates; incidence of invasive disease.
Evidence
Evidence was extracted from data sources in the author’s personal files.
Of particular interest was a 1991 Report of a National [Canadian] Workshop
on Screening for Cancer of the Cervix.
Recommendations were graded as:
|
A
|
Good evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
B
|
Fair evidence to support the recommendation that the condition
be specifically considered in a PHE. |
|
C
|
Poor evidence regarding inclusion or exclusion of the condition
in a PHE, but recommendations may be made on other grounds. |
|
D
|
Fair evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
|
E
|
Good evidence to support the recommendation that the condition
be specifically excluded from consideration in a PHE. |
Quality of evidence was rated according to 5 levels:
|
I
|
Evidence from at least 1 properly randomized controlled
trial (RCT). |
|
II-1
|
Evidence from well-designed controlled trials without randomization. |
|
II-2
|
Evidence from well-designed cohort or case-control analytic
studies, preferably from more than 1 centre or research group. |
|
II-3
|
Evidence from comparisons between times or places with
or without the intervention. Dramatic results in uncontrolled experiments
could also be included here. |
|
III
|
Opinions of respected authorities, based on clinical experience,
descriptive studies or reports of expert committees. |
Values
The 13-member Task Force of experts in family medicine, geriatric medicine,
pediatrics, psychiatry and epidemiology used an evidence-based method for
evaluating the effectiveness of preventive health care interventions. Recommendations
were not based on cost-effectiveness of options. Patient preferences were
not discussed.
Background papers providing critical appraisal of the evidence and tentative
recommendations prepared by the chapter author were pre-circulated to the
members. Evidence for this topic was presented and deliberated upon in
1- to 2-day meetings, 2 to 3 times per year from January 1993 to June 1993.
Consensus was reached on final recommendations.
Benefits,
Harms, and Costs
The false negative error rate of the Papanicolaou smear test is estimated
to be as high as 25%, due to physician or laboratory error. False negative
results can lead to a false sense of security and progression of disease
to a less treatable stage. False positive results are not a major concern
because a second test and colposcopy can be done with minimal risk and
cost.
5-year survival rates vary from 90% for stage I cervical cancer and
10% to 15% for stage IV cancer (p884). Disease progression appears to be
slow (p885). Case-control and cohort studies report that screening reduces
the incidence of invasive cancer. Women who have never been screened, most
of whom are over 50 years, Native or have immigrated from poorer countries,
are at greatest risk of dying from cervical cancer (p887).
Recommendations
Recommendation grade [A, B, C, D, E] and level of evidence
[I, II-1, II-2, II-3, III] are indicated after each recommendation. Citations
in support of individual recommendations are identified in the guideline
text.
-
Fair evidence exists to include (in the PHE) routine screening of sexually
active women for cervical cancer using the Papanicolaou smear [B,
II-2]. Suggested frequency is annual screening
upon initiation of sexual intercourse or at 18 years; after 2 normal tests,
screening every 3 years until age 69. More frequent testing may be considered
for women at high risk (first intercourse at <18 yrs., multiple sexual
partners, consort with multiple sexual partners, smoking, low socioeconomic
status).
Validation
This report was externally peer reviewed. The National Workshop Report
recommended screening every 3 years up to age 69. The 1989 U.S. Preventive
Services Task Force recommended testing of sexually active women every
1 to 3 years to age 65.
Sponsors
The Canadian Task Force on Preventive Health Care
developed this guideline with funding from Health Canada.
Selected
References
Source Document
Other
-
Miller AB, Anderson G, Brisson J, et al. Report of a national workshop
on screening for cancer of the cervix. Can Med Assoc J. 1991;145:1301-25.
Link to Full Text of this
review
Link to Summary Table of Recommendations of this review
Link to Selected References list of this review
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