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© 2005 Oxford University Press
CORRESPONDENCE |
Re: Efficacy of Breast Cancer Screening in the Community According to Risk Level
Affiliation of authors: Unit of Clinical and Descriptive Epidemiology, Centre for Study and Prevention of Cancer, Scientific Institute of Tuscany Region, Florence, Italy
Correspondence to: Eugenio Paci, MD, Unit of Clinical and Descriptive Epidemiology, Centre for Study and Prevention of Cancer, Via di San Salvi 12, 50135 Florence, Italy (e-mail: e.paci{at}cspo.it).
The study by Elmore et al. (1) was designed to evaluate, by means of a case–control design, the effectiveness of early breast cancer diagnosis among women enrolled in six U.S. health plans. Whereas breast cancer screening evaluation in service screening is important, the practice of unorganized screening programs in the United States makes this effort problematic because women are not actively invited to be screened.
We would like to have more details about the following two issues. First, as pointed out by Weiss (2), it is difficult to know the intention of the woman asking for mammography or clinical breast examination because symptoms are not usually reported or not recorded in medical records. Although Elmore et al. carefully reviewed the medical records, it would be useful to compare the frequency of screening tests before the "index period" between the matched case and control subjects. In the absence of the above-mentioned bias of selective reporting, we would expect the frequency of such tests among case subjects and control subjects to be comparable, given the negative result of the study. A lower frequency of screening tests before the index period among case subjects could suggest that unrecorded breast symptoms could have inflated the frequency of index screening tests.
Second, to assess the impact of screening, documentation about the population-based performance of the screening process is needed. In their article, Elmore et al. reported staging of breast cancers for breast cancer deaths only. Assuming that the population-based stage distribution of breast cancer cases is available from cancer registries, it could be interesting to know the changing trends of early and advanced cases over the study period. Moreover, stage distribution of breast cancer cases by screening status would be extremely helpful to validate the expected outcome of a community-based, nonorganized screening program.
REFERENCES
(1) Elmore JG, Reisch LM, Barton MB, Barlow WE, Rolnick S, Harris EL, et al. Efficacy of breast cancer screening in the community according to risk level. J Natl Cancer Inst 2005;97:1035–43.
(2) Weiss NS. Analysis of case-control studies of the efficacy of screening for cancer: how should we deal with tests done in persons with symptoms? Am J Epidemiol 1998;147:1099–102.
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J Natl Cancer Inst 2005 97: 1704-1705.
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