Seventeen-years overview of breast cancer inside and outside screening in Denmark

TY - JOUR

T1 - Seventeen-years overview of breast cancer inside and outside screening in Denmark

AU - Domingo, Laia

AU - Jacobsen, Katja Kemp

AU - von Euler-Chelpin, My Catarina

AU - Vejborg, Ilse

AU - Schwartz, Walter

AU - Sala, Maria

AU - Lynge, Elsebeth

PY - 2013/1

Y1 - 2013/1

N2 - Background. Long-term data on breast cancer detection in mammography screening programs are warranted to better understand the mechanisms by which screening changes the breast cancer pattern in the population. We aimed to analyze 17 years of breast cancer detection rates inside and outside screening in two Danish regions, emphasizing the influence of organizational differences of screening programs on the outcomes. Material and methods. We used data from two long-standing population-based mammography screening programs, Copenhagen and Fyn, in Denmark. Both programs offered biennial screening to women aged 50-69 years. We identified targeted, eligible, invited and participating women. We calculated screening detection and interval cancer rates for participants, and breast cancer incidence in non-screened women (= targeted women excluding participants) by biennial invitation rounds. Tumor characteristics were tabulated for each of the three groups of cancers. Results. Start of screening resulted in a prevalence peak in participants, followed by a decrease to a fairly stable detection rate in subsequent invitation rounds. A similar pattern was found for breast cancer incidence in non-screened women. In Fyn, non-screened women even had a higher rate than screening participants during the first three invitation rounds. The interval cancer rate was lower in Copenhagen than in Fyn, with an increase over time in Copenhagen, but not in Fyn. Screen-detected cancers showed tumor features related with a better prognosis than tumors detected otherwise, as more than 80% were smaller than 20 mm and estrogen receptor positive. Conclusion. Data from two long-standing population-based screening programs in Denmark illustrated that even if background breast cancer incidence and organization were rather similar, performance indicators of screening could be strongly influenced by inclusion criteria and participation rates. Detection rates should be interpreted with caution as they may be biased by selection into the screening population.

AB - Background. Long-term data on breast cancer detection in mammography screening programs are warranted to better understand the mechanisms by which screening changes the breast cancer pattern in the population. We aimed to analyze 17 years of breast cancer detection rates inside and outside screening in two Danish regions, emphasizing the influence of organizational differences of screening programs on the outcomes. Material and methods. We used data from two long-standing population-based mammography screening programs, Copenhagen and Fyn, in Denmark. Both programs offered biennial screening to women aged 50-69 years. We identified targeted, eligible, invited and participating women. We calculated screening detection and interval cancer rates for participants, and breast cancer incidence in non-screened women (= targeted women excluding participants) by biennial invitation rounds. Tumor characteristics were tabulated for each of the three groups of cancers. Results. Start of screening resulted in a prevalence peak in participants, followed by a decrease to a fairly stable detection rate in subsequent invitation rounds. A similar pattern was found for breast cancer incidence in non-screened women. In Fyn, non-screened women even had a higher rate than screening participants during the first three invitation rounds. The interval cancer rate was lower in Copenhagen than in Fyn, with an increase over time in Copenhagen, but not in Fyn. Screen-detected cancers showed tumor features related with a better prognosis than tumors detected otherwise, as more than 80% were smaller than 20 mm and estrogen receptor positive. Conclusion. Data from two long-standing population-based screening programs in Denmark illustrated that even if background breast cancer incidence and organization were rather similar, performance indicators of screening could be strongly influenced by inclusion criteria and participation rates. Detection rates should be interpreted with caution as they may be biased by selection into the screening population.

KW - Aged

KW - Breast Neoplasms

KW - Denmark

KW - False Positive Reactions

KW - Female

KW - Humans

KW - Incidence

KW - Longitudinal Studies

KW - Mammography

KW - Mass Screening

KW - Middle Aged

KW - Prognosis

KW - Program Evaluation

KW - Receptors, Estrogen

U2 - 10.3109/0284186x.2012.698750

DO - 10.3109/0284186x.2012.698750

M3 - Journal article

C2 - 22943386

SN - 1100-1704

VL - 52

SP - 48

EP - 56

JO - Acta Oncologica, Supplement

JF - Acta Oncologica, Supplement

IS - 1

ER -