Published by Oxford University Press on behalf of the International Epidemiological Association ß The Author 2008; all rights reserved. Advance Access publication 19 October 2008
COCHRANE COLUMN
International Journal of Epidemiology 2008;37:1217–1219 doi:10.1093/ije/dyn218
These summaries have been derived from Cochrane reviews published in The Cochrane Database of Systematic Reviews in The Cochrane Library. Their content has, as far as possible, been checked with the authors of the original reviews, but the summaries should not be regarded as an official product of The Cochrane Collaboration (www.cochrane.org).
Taryn Young The aim of the Column is to highlight Cochrane Reviews of relevance to public health, and to stimulate debate on relevance, feasibility and acceptability. Screening to detect early asymptomatic disease, and make an impact on disease outcome, is integral to secondary prevention strategies. Evaluation of screening programmes to assess its’ outcomes is necessary and this month we feature the review on the effects of regular self-examination or clinical examination for early detection of breast cancer.
Regular self-examination or clinical examination for early detection of breast cancer ¨ sters1 and Peter C Gøtzsche2 Jan Peter Ko
Background
Methods
Breast cancer is common in women. Screening may ensure early detection and treatment and be of benefit. Options for screening include regular selfexamination or examination by a health professional. However, the particular cancers detected by screening may themselves have favourable prognosis. They may be slow growing, and some of them might not become invasive if left alone without treatment.1 This means some degree of over diagnosis and over treatment is an inevitable consequence of screening.2 Screening is intuitively attractive for detecting cancers early, and it is therefore important to evaluate rigorously.
The authors searched The Cochrane Library, MEDLINE (PubMed) and the Cochrane Breast Cancer Group (October 2007). They included only randomized trials of women not diagnosed with breast cancer. They sought trials that tested regular self-examination and regular clinical examination.
1
2
The Nordic Cochrane Centre, Rigshospitalet, Department 7112, Copenhagen Ø, Denmark. The Nordic Cochrane Centre, Rigshospitalet, Department 3343, Copenhagen Ø, Denmark.
Results and discussion Two large population-based studies Russia3 and Shanghai4 (388 535 women) compared breast selfexamination with no intervention. There was no statistically significant difference in breast cancer mortality between the groups [relative risk 1.05, 95% confidence interval (CI) 0.90–1.24; 587 deaths in total] (Figure 1). In the Russian study, more cancers were found in the self-examination group than in the control group (relative risk 1.24, 95% CI 1.09–1.41); this was not the case in Shanghai (relative risk 0.97, 95% CI 0.88–1.06). Almost twice as many
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South African Cochrane Centre, South African Medical Research Council, PO Box 19070, Tygerberg 7505, South Africa. E-mail:
[email protected]
The Cochrane Collaboration (http://www.cochrane. org) is an international, non-profit organization that prepares and disseminates up-to-date systematic reviews on the effects of healthcare interventions in order to help people make well-informed decisions. Systematic reviews aim to answer focused healthcare questions by systematically identifying and evaluating all relevant research studies and synthesizing their results. Related to screening and diagnosis, the Collaboration has convened a Cochrane Diagnostic Test Accuracy Working Group to develop and implement reviews of diagnostic test accuracy. If you are interested in contributing to the Cochrane Column or The Cochrane Collaboration, contact me at the South African Cochrane Centre.
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INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
Study or Subgroup Russia 1999 Shanghai 2002
Breast self-exam. Control Events Total Events Total 157 135
57712 132979
164 131
190691
Total (95% CI)
Weight
Risk Ratio M-H, Fixed, 95% CI
64759 133085
54.1% 45.9%
1.07 [0.86, 1.34] 1.03 [0.81, 1.31]
197844
100.0%
1.05 [0.90, 1.24]
292 295 Total events Heterogeneity: Chi² = 0.06, df = 1 (P = 0.81); I² = 0% Test for overall effect: Z = 0.64 (P = 0.52)
Risk Ratio M-H, Fixed, 95% CI
0.5 0.7 1 1.5 2 Favours BSE Favours control
Figure 1 Breast self-examination versus no breast self-examination: mortality from breast cancer
Study or Subgroup Russia 1999 Shanghai 2002 Total (95% CI)
Breast self-exam. Control Total Events Total Weight Events 645 2761
57712 132979
351 64759 1505 133085
190691
Risk Ratio M-H, Fixed, 95% CI
18.0% 82.0%
2.06 [1.81, 2.35] 1.84 [1.73, 1.95]
197844 100.0%
1.88 [1.77, 1.99]
0.5 0.7 1 1.5 2 Favours BSE Favours control
Figure 2 Breast self-examination versus no breast self-examination: total number of breast biopsies with benign histology
biopsies (3406) with benign results were performed in the screening groups compared with the control groups (1856) (relative risk 1.88, 95% CI 1.77–1.99) (Figure 2). One large population-based trial of clinical breast examination combined with breast self-examination from the Philippines5 was also included. The intervention was discontinued because of poor compliance with follow-up and no conclusions could be drawn.
detection of breast cancer. Cochrane Database of Systematic Reviews 2003, Issue 2. Art. No.: CD003373. DOI: 10.1002/14651858.CD003373.
References 1
2
Conclusions The two large trials do not suggest a beneficial effect of screening by regular breast self-examination; whereas, there is evidence for harm. Screening by regular breast self-examination or physical examination cannot be recommended. The full text of the Cochrane Review is available in ¨sters JP, Gøtzsche PC. Regular The Cochrane Library: Ko self-examination or clinical examination for early
3
4
5
Feig SA. Ductal carcinoma in situ. Radiol Clin North Am 2000;38:653–68. Welch H. Should I be tested for cancer? Maybe not and here’s why. Berkeley: University of California Press, 2004. Semiglazov VF, Moiseyenko VM, Manikhas AG et al. Role of breast self-examination in early detection of breast cancer: Russia/WHO prospective randomized trial in St. Petersburg. Cancer Strategy 1999;1:145–51. Thomas DB, Gao DL, Ray RM et al. Randomized trial of breast self-examination: final results. J Natl Cancer Inst 2002;94:1445–57. Pisani P, Parkin DM, Ngelangel C et al. Outcome of screening by clinical examination of the breast in a trial in the Philippines. Int J Cancer 2006;118:149–54.
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Total events 3406 1856 Heterogeneity: Chi² = 2.51, df = 1 (P = 0.11); I ² = 60% Test for overall effect: Z = 21.97 (P < 0.00001)
Risk Ratio M-H, Fixed, 95% CI
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Commentary: ‘Regular self-examination or clinical examination for early detection of breast cancer’ Sheana Jones*
* Gynaecologist, private practice, South Africa.
the two included studies, BSE produced twice as many biopsies with benign results in the screening group compared with the control group. In resource-poor areas, BSE may seem to be an alternative to mammography. This review questions that assumption, but goes on to conclude ‘increased breast awareness may have contributed to the decrease in mortality from breast cancer that has been noted in some countries’. It would seem that BSE is not the only answer, but it may be part of the solution in reducing mortality from breast cancer.
References 1
2
3
¨sters JP, Gøtzsche PC. Regular self-examination or Ko clinical examination for early detection of breast cancer. Cochrane Database of Systematic Reviews 2003, Issue 2. Art. No.: CD003373. DOI: 10.1002/14651858.CD003373. Gøtzsche PC, Nielsen M. Screening for breast cancer with mammography. Cochrane Database of Systematic Reviews 2006, Issue 4. Art. No.: CD001877. DOI: 10.1002/ 14651858.CD001877.pub2. Grimes DA, Schultz KF. Uses and abuses of screening tests. Lancet 2002;359:881–84.
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Breast self-examination (BSE) has been promoted for years as a general screening in an attempt to diagnose breast cancer in its early stages and thus reduce mortality. This review finds there to be no reduction in mortality from breast cancer in women who examine their breasts.1 In fact, it finds that there is an increase in morbidity through increased biopsy.1 The inclusion ages of the studies were different and the Shanghai Group studied women from as young as 30 years, which clearly includes a group of women at lower risk of breast cancer. The inclusion of these younger women may have impacted on their findings. Of concern is the study from the Philippines which was not included because of an unacceptably (and surprisingly), high refusal of screen positive women to undergo further follow-up and intervention. The reasons for this should be explored as this may inform planning of similar screening initiatives. Mammography is the gold standard of breast screening and has shown to reduce mortality by up to 20% in women over 50 years.2 It is however, expensive, uncomfortable and has low sensitivity and a high false positive rate. The alternatives have to be cheaper, safe, valid and reliable.3 It would seem that BSE does not fulfil all these requirements. In one of
