Radiology -- eLetters for Blanchard et al., 240 (2) 335-342

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Breast Imaging:
Karen Blanchard, James A. Colbert, Daniel B. Kopans, Richard Moore, Elkan F. Halpern, Kevin S. Hughes, Barbara L. Smith, Kenneth K. Tanabe, and James S. Michaelson
Long-term Risk of False-Positive Screening Results and Subsequent Biopsy as a Function of Mammography Use
Radiology 2006; 240: 335-342 [Abstract] [Full text] [PDF]

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False-positive Screening As the Cause, Rather than the Effect, of Irregular Screening Attendance: Stefano Ciatto, MD (29 March 2007)

False-positive Screening As the Cause, Rather than the Effect, of Irregular Screening Attendance 29 March 2007

Stefano Ciatto, MD,
radiologist
Centro per lo Studio e la Prevenzione Oncologica
Send letter to journal:
Re: False-positive Screening As the Cause, Rather than the Effect, of Irregular Screening Attendance

s.ciatto{at}cspo.it Stefano Ciatto, MD

Editor:
The finding by Blanchard et al (1) that irregular screening attendance is associated with more frequent false-positive screening results might have an explanation opposite to that given by the authors. A false-positive screening event is a bad experience for a woman, which might discourage, at least for a time, regular attendance at screening. If this is the case, less-frequent attendance might be the effect rather than the cause of a false-positive finding. When analyzing the association of false-positive results to screening attendance over the whole observation period, the authors ignored this possible effect, which may eventually bias their conclusions. A more detailed analysis of the association (eg, checking if delayed attendance follows rather than precedes a false-positive event) might solve the problem. The final statement that regular annual screening is more effective for mortality reduction than less-frequent screening is not supported by any convincing evidence, at least as far as annual versus biennial screening is concerned. It is well known that increasing the screening interval will lead to an increased interval cancer rate, but moving one cancer from the "interval" to the "screen detected" box does not necessarily mean the patient would have died of cancer in the former and be cured in the latter event. The recent findings of the UK frequency trial (2), showing a limited difference in estimated efficacy when comparing annual to triennial screening, suggest that evidence of an increased interval cancer rate may not reliably predict a proportionate decrease of screening efficacy.
References
1. Blanchard K, Colbert JA, Kopans DB, et al. Long-term risk of false-positive screening results and subsequent biopsy as a function of mammography use. Radiology 2006;240(2):335-342.
2. Breast Screening Frequency Trial Group. The frequency of breast cancer screening: results from the UKCCCR Randomised Trial. Eur J Cancer 2002;38(11):1458-1464.
Dr Michaelson responds:

Dr Ciatto’s hypothesis on the effect of false-positive findings on screening behavior is not borne out empirically: As we reported previously (1), women who underwent a biopsy that did not reveal cancer actually became more likely to return on time for subsequent screening mammography.
Contrary to Dr Ciatto’s assertion, the UK frequency trial, in fact, reported that annual screening results in a decrease in the average size at which invasive breast cancers are brought to medical attention (2). Similar results were reported by Hunt et al (3). Computer simulation studies from our own group (1,4,5) and others (6,7 and references therein), as well as studies of the time-course of the appearance of larger palpable cancers after a negative mammogram (8-10 and references therein) suggest that annual screening should lead to marked reductions in both the average size at which invasive breast cancers are brought to medical attention and to considerable reductions in the breast cancer death rate.
References
1. Blanchard K, Colbert JA, Puri D, et al. Mammographic screening: patterns of use and estimated impact on breast carcinoma survival. Cancer 2004;101(3):495-507.
2. Breast Screening Frequency Trial Group. The frequency of breast cancer screening: results from the UKCCCR Randomised Trial. Eur J Cancer 2002;38(11):1458-1464.
3. Hunt KA, Rosen EL, Sickles EA. Outcome analysis for women undergoing annual versus biennial screening mammography: a review of 24,211 examinations. AJR Am J Roentgenol 1999;173(2):285-289.
4. Michaelson JS. Using information on breast cancer growth, spread, and detectability to find the best ways to use screening to reduce breast cancer death. Woman’s Imaging 2001;3:54-57.
5. Michaelson JS, Halpern E, Kopans D. Breast cancer: computer simulation method for estimating optimal intervals for screening. Radiology 1999;212(2):551-560.
6. Wai ES, D’yachkova Y, Olivotto A, et al. Comparison of 1- and 2-year screening intervals for women undergoing screening mammography. Br J Cancer 2005;92(5):961-966.
7. Michaelson JS, Kopans D, Cady B. The breast cancer screening interval is important. Cancer 2000;88:1282-1284.
8. Michaelson J, Satija S, Moore R, et al. The pattern of breast cancer screening utilization and its consequences. Cancer 2002;94(1):37-43.
9. Michaelson JS, Satija S, Moore R, Weber G, Garland G, Kopans DB. Estimates of the breast cancer growth rate and sojourn time from screening database information. Journal of Women’s Imaging 2003;5:3-10.
10. Michaelson JS, Satija S, Kopans DB, et al. Gauging the impact of breast carcinoma screening in terms of tumor size and death rate. Cancer 2003;98(10):2114-2124.