Breast cancer incidence and overdiagnosis in Catalonia SpainReport as inadecuate

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Breast Cancer Research

, 12:R58

First Online: 03 August 2010Received: 08 April 2010Revised: 13 July 2010Accepted: 03 August 2010


IntroductionEarly detection of breast cancer BC with mammography may cause overdiagnosis and overtreatment, detecting tumors which would remain undiagnosed during a lifetime. The aims of this study were: first, to model invasive BC incidence trends in Catalonia Spain taking into account reproductive and screening data; and second, to quantify the extent of BC overdiagnosis.

MethodsWe modeled the incidence of invasive BC using a Poisson regression model. Explanatory variables were: age at diagnosis and cohort characteristics completed fertility rate, percentage of women that use mammography at age 50, and year of birth. This model also was used to estimate the background incidence in the absence of screening. We used a probabilistic model to estimate the expected BC incidence if women in the population used mammography as reported in health surveys. The difference between the observed and expected cumulative incidences provided an estimate of overdiagnosis.

ResultsIncidence of invasive BC increased, especially in cohorts born from 1940 to 1955. The biggest increase was observed in these cohorts between the ages of 50 to 65 years, where the final BC incidence rates more than doubled the initial ones. Dissemination of mammography was significantly associated with BC incidence and overdiagnosis. Our estimates of overdiagnosis ranged from 0.4% to 46.6%, for women born around 1935 and 1950, respectively.

ConclusionsOur results support the existence of overdiagnosis in Catalonia attributed to mammography usage, and the limited malignant potential of some tumors may play an important role. Women should be better informed about this risk. Research should be oriented towards personalized screening and risk assessment tools.


BCbreast cancer

BCSPCatalan Breast Cancer Screening Program

CFRcompleted fertility rate

CISNETCancer Intervention and Surveillance Modeling Network

DCISductal carcinoma in situ

HRThormone replacement therapy

LZLee and Zelen

PM50proportion of women receiving periodic mammograms at age 50

USAUnited States of America.

Electronic supplementary materialThe online version of this article doi:10.1186-bcr2620 contains supplementary material, which is available to authorized users.

Montserrat Martinez-Alonso, Ester Vilaprinyo contributed equally to this work.

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Author: Montserrat Martinez-Alonso - Ester Vilaprinyo - Rafael Marcos-Gragera - Montserrat Rue


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