Chapter IV. Reduced breast-cancer mortality with mammography screening-an assessment of currently available data
✍ Scribed by Lars E. Rutqvist; Anthony B. Miller; Ingvar Andersson; Matti Hakama; Timo Hakulinen; Baldur F. Sigfússon; Làszlo Tabár
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- French
- Weight
- 860 KB
- Volume
- 46
- Category
- Article
- ISSN
- 0020-7136
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✦ Synopsis
Possible measures to decrease breast-cancer mortality include prevention and improved treatment. Although there may be some strategies that can now be adopted for prevention, their effect will probably be delayed in time. Prevention is also difficult, since it may entail changes in life-style that will not be accepted by all women despite promises of a reduced future risk of breast cancer. Adjuvant systemic therapy has recently been shown to reduce case-fatality during the first 5 years by 20-30% (Early Breast Cancer Trialists' Collaborative Group, 1988). Despite these encouraging early results, many patients still die of their disease and the long-term benefit of adjuvant therapy is not well known. Evaluation of other strategies to improve the outcome of treatment is clearly warranted, e . g . , early diagnosis through mass screening.
Most breast-cancer deaths are caused by distant metastases. The probability of distant dissemination is related to the clinical stage at presentation. Many patients with small tumors without axillary nodal involvement achieve long-term survival with local treatment alone. The risk of disease recurrence and early death is considerably higher among patients with large, node-positive tumors. Therefore, it appears reasonable to assume that early detection and treatment should improve outcome. Since this assumption is not self-evident, the applicability of screening as a method to reduce breast-cancer mortality should be evaluated in the context of controlled trials.
Many factors other than breast-cancer mortality should be considered in a comprehensive evaluation of screening, e.g., the benefit of being able to use breast-preserving surgery in patients with small tumors, a decreased need of systemic treatment, and a reduced fear of breast cancer among women with a negative screening result, the potential disadvantages of undue anxiety caused by the screening and risk of diagnosing biologically benign lesions as cancer, the cost, inconvenience, and harm of negative biopsies, and the overall cost of the screening program. Several end-points are of interest, such as attendance rate, number of detected cases, stage distribution, interval cancers, mortality and others (Prorok et al., 1984). However, this report will focus on the potential benefit of screening in terms of reduced breast-cancer mortality, since this invariably has been the main objective of the controlled trials. Moreover, breast-cancer death is the only end-point of enough importance to justify the resources spent.
SUMMARY OF AVAILABLE STUDIES
'Breast cancer cases detected within 5 years.-*Relative benefit at 18 years reduced to 23% .-3Population offered physical examination plus mammography vs. reference population.