Preventive health care, 2001 update: Should women be routinely taught breast self-examination to screen for breast cancer?
Prepared by N. Baxter, MD, PhD, FRCS (C), with the Canadian Task Force on Preventive Health Care
These recommendations were finalized by the Task Force in October 2000.
(1)
To evaluate the evidence relating to the effectiveness of breast
self-examination to screen for breast cancer, and (2) to provide recommendations
for teaching of breast self-examination to women as part of a periodic health
examination.
Breast
cancer is the most frequently diagnosed cancer among Canadian women and accounts
for 30% of all new cancer cases each year. In Canada, 19,200 new diagnosed cases
of breast cancer and 5,500 deaths from the disease were estimated for the year
2000. The current age-standardized incidence and mortality rates for Canada are
106 and 27 per 100,000 respectively. The lifetime risk of dying of breast cancer
is one in 25.8. Breast cancer is the number one cause of person-years of life
lost for women.
This
review considers the routine teaching to women, by health professionals, of
breast self-examination. Breast self-examination is defined as a systematic
method of palpation of the breast and axilla, not casual or ad hoc palpation.
For breast cancer screening generally, current evidence supports
mammography and clinical breast examination for women 50-69. For women 40-49,
the evidence is insufficient to recommend for or against routine screening. For
women above the age of 70 there is limited evidence regarding the benefit of
screening.
With
the help of a reference librarian Medline, Premedline, CINAHL, HealthStar,
Current Contents, and the Cochrane Library were searched from 1966- October 2000
using the terms:
The search was restricted to publications with English abstracts. Abstracts
of all retrieved papers were read; those relevant to the review were critically
appraised. Related articles and reference lists of key articles were searched
and experts in the field were consulted to ensure that no significant studies
were missed.
Recommendations were graded as:
| Good evidence to support the recommendation that the condition be specifically considered in a PHE. | |
| Fair evidence to support the recommendation that the condition be specifically considered in a PHE. | |
| Poor evidence regarding inclusion or exclusion of the condition in a PHE, but recommendations may be made on other grounds. | |
| Fair evidence to support the recommendation that the condition be specifically excluded from consideration in a PHE. | |
| 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:
| Evidence from at least 1 properly randomized controlled trial (RCT). | |
| Evidence from well-designed controlled trials without randomization. | |
| Evidence from well-designed cohort or case-control analytic studies, preferably from more than 1 centre or research group. | |
| Evidence from comparisons between times or places with or without the intervention. Dramatic results in uncontrolled experiments could also be included here. | |
| Opinions of respected authorities, based on clinical experience, descriptive studies or reports of expert committees. |
The
10-member Task Force of experts in family medicine, geriatric medicine,
paediatrics, 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 primary author were
pre-circulated to the members. Evidence
for this topic was presented and deliberated upon in 1- to
2-day meetings from Nov 1999 to October 2000.
Consensus was reached on final recommendations.
Estimates derived from one study suggest that the overall sensitivity of
BSE alone was 26% in screened women, assuming that all interval cancers were
detected by BSE. Sensitivity varied with age from 41% for women aged 35-39 to
21% in women aged 60-74. Specificity
was not estimated.
In studies of lump detection in silicone breast models, sensitivity
ranged from 40% to 89%, while specificity ranged from 66% to 81%. The
sensitivity of lump detection in silicone models has been shown to be lower in
women over 60 as compared to younger women. While sensitivity improved with
training, so did the rate of false positive detection.
None of the studies, including 2 large randomized controlled trials, a
quasi-randomized trial, a large cohort and several case-control studies, showed
a benefit for regular performance of BSE or BSE education, compared to no BSE.
In randomised controlled trials with up to 9 years of follow-up, no
significant differences were found in: the number of breast cancers detected,
stage at diagnosis, or breast cancer deaths. The effect of BSE technique was
evaluated in secondary analyses of case-control studies. While there was
demonstration of benefit in some sub-groups no statistical adjustment was made
for multiple comparisons.
There is good evidence of harm from BSE instruction, including significant increases in physician visits for the evaluation of benign breast lesions and significantly higher rates of benign breast biopsies. The teaching and reinforcement of BSE are costly and may divert resources from other preventive activities.
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.
Women aged 50 to 69: Because there is fair evidence of no benefit, and good evidence of harm, there is fair evidence to support the recommendation that routine teaching of BSE be excluded from the periodic health examination [D, I, II-1, II-3].
Women aged 40 to 49: Because there is fair evidence of no benefit, and good evidence of harm, there is fair evidence to support the recommendation that routine teaching of BSE be excluded from the periodic health examination [D, I, II-1, II-3]. While the evidence indicates no benefit from routine instruction, some women will request teaching in BSE. The pros and cons should be discussed with the woman, and if BSE is taught, care must be taken to ensure that BSE is conducted in a proficient manner.
There
is insufficient evidence for effectiveness of the maneuver in women younger than
40 or older than 70 years, thus precluding making recommendations for teaching
breast self-examination to women in these age groups. The following issues may
be important to consider: Women younger than 40 years: There
is little evidence for effectiveness specific to this group. As the incidence of
breast cancer is low in this age group, the risk for net harm is even more
likely. Women 70 years or older: Though
the incidence of breast cancer is high in this group, there is insufficient
evidence to make a recommendation for women over age 70 years.
N. Baxter with the Canadian Task Force on Preventive Health Care. Preventive health care, 2001 update: Should women be routinely taught breast self-examination to screen for breast cancer? CMAJ 2001; 164(13):1837-46.