Trends in detection of invasive cancer and ductal carcinoma in situ at biennial screening mammography in Spain: a retrospective cohort study

PLoS One. 2013 Dec 23;8(12):e83121. doi: 10.1371/journal.pone.0083121. eCollection 2013.

Abstract

Background: Breast cancer incidence has decreased in the last decade, while the incidence of ductal carcinoma in situ (DCIS) has increased substantially in the western world. The phenomenon has been attributed to the widespread adaption of screening mammography. The aim of the study was to evaluate the temporal trends in the rates of screen detected invasive cancers and DCIS, and to compare the observed trends with respect to hormone replacement therapy (HRT) use along the same study period.

Methods: Retrospective cohort study of 1,564,080 women aged 45-69 years who underwent 4,705,681 screening mammograms from 1992 to 2006. Age-adjusted rates of screen detected invasive cancer, DCIS, and HRT use were calculated for first and subsequent screenings. Poisson regression was used to evaluate the existence of a change-point in trend, and to estimate the adjusted trends in screen detected invasive breast cancer and DCIS over the study period.

Results: The rates of screen detected invasive cancer per 100.000 screened women were 394.0 at first screening, and 229.9 at subsequent screen. The rates of screen detected DCIS per 100.000 screened women were 66.8 at first screen and 43.9 at subsequent screens. No evidence of a change point in trend in the rates of DCIS and invasive cancers over the study period were found. Screen detected DCIS increased at a steady 2.5% per year (95% CI: 1.3; 3.8), while invasive cancers were stable.

Conclusion: Despite the observed decrease in breast cancer incidence in the population, the rates of screen detected invasive cancer remained stable during the study period. The proportion of DCIS among screen detected breast malignancies increased from 13% to 17% throughout the study period. The rates of screen detected invasive cancer and DCIS were independent of the decreasing trend in HRT use observed among screened women after 2002.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Breast Neoplasms / diagnosis*
  • Breast Neoplasms / diagnostic imaging
  • Breast Neoplasms / epidemiology
  • Breast Neoplasms / pathology
  • Carcinoma, Ductal, Breast / diagnosis*
  • Carcinoma, Ductal, Breast / diagnostic imaging
  • Carcinoma, Ductal, Breast / epidemiology
  • Carcinoma, Ductal, Breast / pathology
  • Carcinoma, Intraductal, Noninfiltrating / diagnosis*
  • Carcinoma, Intraductal, Noninfiltrating / diagnostic imaging
  • Carcinoma, Intraductal, Noninfiltrating / epidemiology
  • Carcinoma, Intraductal, Noninfiltrating / pathology
  • Early Detection of Cancer / trends*
  • Female
  • Hormone Replacement Therapy / statistics & numerical data
  • Humans
  • Incidence
  • Mammography
  • Mass Screening / statistics & numerical data
  • Middle Aged
  • Retrospective Studies
  • Spain / epidemiology

Grant support

This work was supported by grants from the Instituto de Salud Carlos III-FEDER (PI11/01296 and PI09/90251). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.