World Cancer Research Day 2023: an international study of mammographic density

To mark World Cancer Research Day, on 24 September, and promote this year’s theme of “integrating diversity, advancing research, and achieving equity”, the International Agency for Research on Cancer (IARC) is highlighting some of the research projects that IARC scientists are conducting to ensure that diverse populations are represented and included in cancer research, so that underrepresented groups can benefit from advances in prevention and early detection.

Mammographic density – the proportion of a breast that is made up of radiodense fibroglandular tissue – is a strong marker of breast cancer risk. Breast cancer incidence rates vary more than 6-fold between countries worldwide, but it is not known whether international variations in population-level mammographic density distributions parallel differences in breast cancer incidence rates and, if so, what accounts for these variations.

The International Consortium on Mammographic Density, which is coordinated by IARC, has collected data and original digitized and digital mammograms from studies in more than 20 countries worldwide. These include low- and middle-income countries and span populations with low, medium, and high incidence rates of breast cancer. In addition to geographical and income-level differences, studies of diverse ethnic groups are also included.

The goal of the consortium is to create the first standardized pooled data and paired imaging resource, through the collection and analysis of individual-level risk factor data and mammograms from general population studies conducted worldwide. This resource is being used to describe and account for international variations in mammographic density and to investigate to what extent they contribute to international variations in breast cancer incidence rates.