Dense Breast Tissue Obscures Cancer Detection in Irish Screening Programs
Around 43% of women who undergo mammograms in Ireland have dense breasts, a common and normal anatomical trait that can obscure cancer detection. Having dense breasts means a woman has more fibrous and glandular tissue and less fatty tissue, making consultant radiologists’ jobs more difficult since both milk ducts and tumors appear white on a mammogram.
According to Professor Zoe Winters, a senior consultant oncoplastic breast cancer surgeon and breast specialist based in London, a 2022 study shows as many as 50% of cancers are missed on mammograms of women with extremely dense breasts. This masking effect increases cancer risk by 1.5 times for heterogeneously dense breasts and two to four times for extremely dense breasts, often leading to later clinical stages or interval cancers detected between screening rounds.
HSE does not use breast density for automatic screening
The Health Service Executive (HSE) states that breast density is taken into account alongside symptoms, clinical examinations, and imaging findings when clinicians evaluate symptomatic patients. However, density itself does not automatically trigger further imaging or tests. It is not automatically included in population-wide breast screening programs, which target age groups where density is less common and decisions rely on evidence of benefit and harm across an entire population.
Winters explains that dense breasts can only be detected via mammography, meaning patients cannot feel density by touch. It is distinct from lumpy breasts and bears no relation to breast size or appearance. For patients like Siobhán Freeney from Gorey, County Wexford, that limitation proved critical. Freeney received a clear mammogram a few months before November 2015, when she was diagnosed with stage 3 lobular cancer at age 55 after noticing a pull on her right nipple. A subsequent triple assessment revealed a 7cm tumor that her consultant noted was slow-growing and likely masked by her dense tissue for seven or eight years.
Evan Holton seeks private ultrasound after mammogram limitations
Evan Holton, a 51-year-old from Dublin, took a proactive approach to her health due to her mother’s breast cancer scare, beginning private mammograms at age 45 before the official screening age of 50. During a follow-up at St Vincent’s Private Hospital, a radiologist noted her dense tissue, prompting Holton to research the implications of mammogram limitations.
Despite having no symptoms, Holton requested a GP referral for a breast ultrasound in April 2026. Although her GP initially demurred because she lacked symptoms, he provided the referral letter. The June ultrasound revealed a 10-millimeter invasive lobular cancer in her right breast, alongside a non-invasive tumour and a left-breast radial scar discovered via MRI.
Freeney and Holton have since joined forces for the BeingDense campaign, pushing for breast density reporting in all mammograms. In 2021, the group submitted a formal proposal to the National Screening Advisory Committee (NASC) calling for BreastCheck reporting. The Health Information and Quality Authority (Hiqa) informed RTÉ Radio 1’s Liveline in September 2026 that a finalized review and preliminary report on screening extensions and standardised breast density notification would not arrive until the end of 2027.
While Freeney acknowledges that rigorous assessments take time, she urges the health minister to implement an interim protocol providing women with their density information during the review. Liz Yeates, CEO of the Marie Keating Foundation, welcomed Hiqa’s review of the screening pathway, emphasizing that women require clear, accessible information.
Frequently Asked Questions About Breast Density
Can you feel or see if you have dense breasts?
No, dense breasts cannot be detected by self-examination, touch, or visual appearance. According to medical experts, breast density can only be identified through a mammogram and is distinct from having lumpy breasts or any specific breast size or shape.
What additional tests help detect cancer in dense breasts?
Additional screening methods such as ultrasound or MRI can help identify abnormalities that standard mammograms might miss when dense fibroglandular tissue masks potential tumors, as demonstrated in clinical cases where patients pursued secondary imaging after normal mammogram results.
What changes are advocacy groups seeking from Irish health authorities?
Campaign groups including BeingDense and Lobular Breast Cancer Ireland are petitioning the government and the National Screening Advisory Committee to introduce standardized breast density reporting for all mammograms, allowing patients to make informed decisions about supplemental screening.
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