Research article
Estimate of overdiagnosis of breast cancer due to mammography after adjustment for lead time. A service screening study in Italy
-
* Corresponding author: Eugenio Paci e.paci@cspo.it
1 Clinical and Descriptive Epidemiology Unit, CSPO, Research Institute of the Tuscany Region, via di San Salvi 12, Firenze, 50135, Italy
2 ASL Bologna Area Nord, via Libertà 45, 40016, San Giorgio di Piano, Bologna, Italy
3 U.O. Oncologia, Azienda Ospedaliera-Università, Parma Cancer Registry, via Abbeveratoia 4, Parma, 43100, Italy
4 Dipartimento Interaziendale di Oncologia, Ospedale G.B. Morgagni–L. Pierantoni, Pad. Valsava, Romagna Cancer Registry, via C. Forlanini 34, Forlì, 47100, Italy
5 Modena Cancer Registry, via del Pozzo 71, Modena 41100, Italy
6 Ferrara Cancer Registry, Dipartimento di Medicina Sperimentale e Diagnostica, Sezione di Anatomia, Istologia e Citologia Patologica, Università di Ferrara, v. Fossato di Mortara 64B, Ferrara, 44100, Italy
7 Epidemiology Unit, Reggio-Emilia Cancer Registry, via Amendola 2, Reggio-Emilia, 42100, Italy
8 Screening Programme, Emilia-Romagna Region Health Department, viale Aldo Moro 21, 40127, Bologna, Italy
9 CPO – Piedmont Cancer Registry, via San Francesco da Paola 31, Torino,10123, Italy
10 CPO Piemonte, Epidemiology Unit, via San Francesco da Paola 31, Torino, 10123, Italy
11 Umbria Cancer Registry, Dipartimento di specialità Medico-Chirurgiche e Sanità Pubblica, Università degli Studi di Perugia, via del Giochetto, Perugia, 06100, Italy
12 Department of Oncology, ARNAS Ascoli, via Parlavechio 1, 90100, Palermo, Italy
13 Department of Oncology 'Sebastiano Ferrara', Cancer Registry andUnit of Histopathology Azienda Ospedaliera 'Civile M.P. Arezzo', via Dante 109, Ragusa, 97100, Italy
14 Dipartimento di Scienze oncologiche e chirurgiche, Università degli Studi di Padova, Istituto Oncologico Veneto (IOV), via Gattamelata 64, Padova, 35128, Italy
Breast Cancer Research 2006, 8:R68 doi:10.1186/bcr1625
Published: 5 December 2006Abstract
Introduction
Excess of incidence rates is the expected consequence of service screening. The aim of this paper is to estimate the quota attributable to overdiagnosis in the breast cancer screening programmes in Northern and Central Italy.
Methods
All patients with breast cancer diagnosed between 50 and 74 years who were resident in screening areas in the six years before and five years after the start of the screening programme were included. We calculated a corrected-for-lead-time number of observed cases for each calendar year. The number of observed incident cases was reduced by the number of screen-detected cases in that year and incremented by the estimated number of screen-detected cases that would have arisen clinically in that year.
Results
In total we included 13,519 and 13,999 breast cancer cases diagnosed in the pre-screening and screening years, respectively. In total, the excess ratio of observed to predicted in situ and invasive cases was 36.2%. After correction for lead time the excess ratio was 4.6% (95% confidence interval 2 to 7%) and for invasive cases only it was 3.2% (95% confidence interval 1 to 6%).
Conclusion
The remaining excess of cancers after individual correction for lead time was lower than 5%.