Download Screening Mammography for Breast Cancer: American College of

Screening Mammography for Breast Cancer:
American College of Preventive Medicine
Practice Policy Statement
Rebecca Ferrini, MD, Elizabeth Mannino, MD, Edith Ramsdell, MD
and Linda Hill, MD, MPH
Burden of suffering
Breast cancer is the most frequently diagnosed cancer and is the second leading
cause of cancer death among women in the United States. Projected for 1996
are 184,300 new cases of breast cancer and 44,300 breast cancer deaths. The
five-year survival rate is 84% for Caucasian, non-Hispanic women and 69% for
African-American women.(1) Risk factors for breast cancer include age, family
history (FH), and familial cancer syndrome (FCS), as well as hormonal factors
such as early menarche, late menopause, late parity, and nulliparity; however,
the majority of women with breast cancer have no known risk factors. Risk
factors, pathogenesis, prognosis, and course differ significantly in
premenopausal and postmenopausal breast cancer.(2)
Description of preventive measures
Mammography is one of several screening tools for detecting early breast
cancer. Other measures, such as clinical and self-breast examinations, will be
addressed in future practice policy statements. During mammography, the
breast should be compressed and two views taken. Plain film or
xeromammography are appropriate.(3) Sensitivity is dependent on the quality
of the equipment, competence of the radiology staff, and the density of the
breast tissue.
Since implementation of the Mammography Quality Standards Act in 1994, all
U.S. mammography centers must be certified by the Food and Drug
Administration.
Evidence of effectiveness
Estimates of mammography sensitivity range from 75% to 90% with specificity
from 90% to 95%. The positive predictive value of mammography for breast
cancer ranges from 20% in women under age 50 to 60% to 80% in women age
50-69. Randomized clinical trials (RCTs) have demonstrated a 30% reduction
in breast cancer mortality in women 50-69 years who are screened annually or
biennially with mammograms. (4) The data on women under age 50 are less
clear. Conclusions regarding the value of mammography in these women are
hampered by inadequately designed studies, including failure of randomization
and inadequate sample size, low compliance in the intervention group, and high
screening rates (cross-over) in the control groups. (5,6) A few studies have
suggested adverse effects on mortality in the early years after screening
implementation, but both the occurrence and potential etiology of these effects
are poorly understood. (6,7) Even with meta-analysis, the combined sample
sizes are too small to reach conclusions regarding the efficacy of screening
women under age 50. (8) Likewise, data are sparse regarding efficacy of
screening mammograms in women older than age 69. Constantly updated
analyses of research on the effectiveness of mammograms for particular groups
are available through the National Cancer Institute by calling 1-800-4CANCER.
Public policy considerations
Currently, compliance with mammography guidelines is low, especially among
women over age 60, those with low socioeconomic status, and ethnic minority
women. Estimates vary widely; 10%-60% of women report having had
mammograms in the preceding year, depending on the population and
geographic area under consideration. (9) Low utilization of mammography has
been blamed on financial/insurance barriers, lack of education, and most
importantly, lack of encouragement by a physician. (10) Both primary care
physicians and specialist physicians should encourage their patients to have
routine mammography: a recommendation from a physician is the most
important motivator for patients. Medical offices can improve patient
compliance by using reminder systems, ancillary health personnel for health
education, and a comprehensive approach to preventive services. Costeffectiveness estimates of mammography screening--based on methodology,
population, and interval--vary widely; it is estimated that breast cancer
screening costs $3,400 to over $83,000 per life-year saved. (11) The potential
cost-effectiveness of screening is higher when screening older populations,
partly because the incidence of breast cancer increases with age.
Recommendations of other groups
The American Cancer Society, American College of Radiology, and the
American College of Obstetricians and Gynecologists recommend screening
mammography for women age 40-49 every 1-2 years and annually after age 50.
The American College of Physicians recommends biennial screening for
women age 50-74 years. The American Academy of Family Physicians, which
recommends mammography screening for women over age 50, is currently
updating its guidelines. The Canadian Task Force on the Periodic Health
Examination recommends annual mammography for women age 50-69 and
recommends against mammography screening for women age 40-49. Similarly,
the U.S. Preventive Services Task Force recommends mammography screening
every 1-2 years for women age 50-69.
Rationale
Population-based mammography screening aims to reduce morbidity and
mortality from breast cancer by early detection and treatment of occult
malignancies. There is ample evidence from a variety of well-conducted RCTs
that annual or biennial mammography is effective in reducing breast cancer
mortality in women 50-69 years. The college provides no recommendations for
women under 50 years because of lack of evidence of the efficacy of screening
in this group and differences between premenopausal and postmenopausal
women in breast density, breast cancer incidence, sensitivity and specificity of
mammography, incidence of false-positive results, tumor growth, mortality
rates, and the suggestion of increased mortality with mammography screening.
Although data are sparse regarding the efficacy of mammography screening in
women over age 69, similarities between women age 50-69 and older women
in terms of breast density, sensitivity and specificity of mammography, tumor
growth, mortality rates, and response to treatment, coupled with the higher
incidence of breast cancer in this age group, point to a need to screen older
women whose health would permit breast cancer treatment. (12) Lack of
outcomes evidence makes it difficult to develop specific recommendations for
high-risk women.
American College of Preventive Medicine Recommendation For
Mammography Screening
Low-risk women (no family history, familial cancer syndrome, or prior
cancer)
There is inadequate evidence for or against mammography screening of women
under age 50. Women between ages 50 and 69 should have annual or biennial,
high-quality, two-view mammography. Women aged 70 or older should
continue undergoing mammography screening provided their health status
permits breast cancer treatment.
Higher-risk women
Women with a family history of premenopausal breast cancer in a first-degree
relative or those with a history of breast and/or gynecologic cancer may warrant
more aggressive screening. Women with these histories often begin screening
at an earlier age, although there is no direct evidence of effectiveness to support
this practice. The future availability of genetic screening may define new
recommendations for screening high-risk women. (13,14)
The college recommends further research to clarify the risk/benefit ratio of
mammography screening for breast cancer in women under age 50, particularly
to identify women in this age group who benefit most from screening. To
compensate for inadequate sample size, another well-designed RCT, a metaanalysis using individual (rather than summary) data, or a well-designed
population-based cohort or case-control study is needed. Further studies should
address whether menopausal status rather than age is a better predictor of the
utility of mammography screening and whether recommendations should be
modified for women taking hormone replacement therapy.
REFERENCES
1. Parker S, Tong L, Bolden S, Wingo P. Cancer Statistics 1996. CA Cancer J Clin 1996;46:8-9.
2. Colditz G. Epidemiology of breast cancer: findings from the nurses health study. CA Suppl
1993;71:1480-9
3. Hendrick RE. Mammography quality assurance: current issues. Cancer 1993;72(4 suppl):1466-74.
4. Elwood JM, Cox B, Richardson AK. The effectiveness of breast cancer screening by mammography in
younger women. Online J Clin Trials 1993;2:Doc no 32.
5. Miller AB, Baines CJ, To T, et al. Canadian national breast screening study 1: breast cancer detection
and death rates among women ages 40-49 years. Can Med Assoc J 1992;147:1459-98.
6. Nystrom L, Rutqvist I, Wall S, et al. Breast cancer screening with mammography: overview of Swedish
randomized trials. Lancet 1993;341:973-8.
7. Vogel V. Screening younger women for breast cancer. J Natl Cancer Inst 1994;16:55-60.
8. Kopans D. Screening for breast cancer and mortality reduction among women 40-49 years of age. CA
Suppl 1994;74:311-22
9. Caplan LS, Wells BL, Haynes S. Breast cancer screening among older racial/ethnic minorities and
whites: barriers to early detection. JGerontol 1992;47:101-10.
10. Fox SA, Stein JA. The effect of physician-patient communication on mammography utilization by
different ethnic groups. Med Care 1991;29:1065-82.
11. Brown ML, Fintor L. Cost-effectiveness of breast cancer screening: preliminary results of a systematic
review of the literature. Breast Cancer Res Treat 1993;25:113-8.
12. Moskowitz M. Guidelines for screening for breast cancer: is a revision in order? Radiol Clin North Am
1992;30:221-33.
13. Bondy M, Lustbader E, Halabi S, et al. Validation of a breast cancer risk assessment model in women
with a positive family history. JNatl Cancer Inst 1994;86:620-4.
14. Thompson W. Genetic epidemiology of breast cancer. CA Suppl 1994;74:279-87.
From the UCSD/SDSU General Preventive Residency, San Diego, California
Address reprint requests to Dr. Hill, San Diego State University, 5500
Campanile Drive,
San Diego, CA 92182-4701.
Published: American Journal of Preventive Medicine September/October
1996;12(5):340-41.
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