Change in mammographic density across birth cohorts of Dutch breast cancer screening participants

Int J Cancer. 2019 Dec 1;145(11):2954-2962. doi: 10.1002/ijc.32210. Epub 2019 Feb 27.


High mammographic density is a well-known risk factor for breast cancer. This study aimed to search for a possible birth cohort effect on mammographic density, which might contribute to explain the increasing breast cancer incidence. We separately analyzed left and right breast density of Dutch women from a 13-year period (2003-2016) in the breast cancer screening programme. First, we analyzed age-specific changes in average percent dense volume (PDV) across birth cohorts. A linear regression analysis (PDV vs. year of birth) indicated a small but statistically significant increase in women of: 1) age 50 and born from 1952 to 1966 (left, slope = 0.04, p = 0.003; right, slope = 0.09, p < 0.0001); 2) age 55 and born from 1948 to 1961 (right, slope = 0.04, p = 0.01); and 3) age 70 and born from 1933 to 1946 (right, slope = 0.05, p = 0.002). A decrease of total breast volume seemed to explain the increase in PDV. Second, we compared proportion of women with dense breast in women born in 1946-1953 and 1959-1966, and observed a statistical significant increase of proportion of highly dense breast in later born women, in the 51 to 55 age-groups for the left breast (around a 20% increase in each age-group), and in the 50 to 56 age-groups for the right breast (increase ranging from 27% to 48%). The study indicated a slight increase in mammography density across birth cohorts, most pronounced for women in their early 50s, and more marked for the right than for the left breast.

Keywords: breast cancer screening; mammographic density; secular trends; volumetric breast density.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Breast / diagnostic imaging*
  • Breast Density*
  • Breast Neoplasms / diagnostic imaging
  • Breast Neoplasms / epidemiology*
  • Early Detection of Cancer / methods*
  • Female
  • Humans
  • Mammography
  • Middle Aged
  • Netherlands
  • Regression Analysis