Interval cancer detection rate increased with breast density notification

A new study led by InforMD member A/Prof Jennifer Stone has found higher rates of interval-detected breast cancers in the first year after women are notified they have dense breasts, compared to the second year. This study highlights the importance of providing information that enables women to seek further advice and potentially supplementary screening, if recommended.

Women with increased breast density for their age are at slightly increased risk of breast cancer AND a higher risk of a cancer going undetected at mammographic screening. Dense breasts can hide cancers as both tumours and breast density appear white on a mammogram. An interval cancer is a cancer detected in between screening appointments – meaning the cancer is detected after an “all-clear” screening mammogram and before the time when the next screen would have been scheduled. A “true” interval is a cancer that is not present or visible at the time of screening but develops quickly thereafter and is detected as a result of a symptom (e.g. feeling a lump or indentation). A “missed” interval is a cancer that is present but missed at the time of screening. Dense breasts can hide cancers as both tumours and breast density appear white on a mammogram. So women with increased breast density for their age are at slightly increased risk of breast cancer, and a higher risk of a cancer going undetected at mammographic screening.

The new study by A/Prof Stone and colleagues compared interval cancer detection rates within 0-12 months after normal screening and those 13-24 months after normal screening. Given the time it takes for many cancers to appear as a symptom, interval cancer detection rates should increase with time from screening, not the reverse.

But this was not the case for clients notified that they have dense breasts by BreastScreen WA. Higher interval cancer detection rates were observed in the first 12 months after normal screening than in months 13–24. The study authors suggest that following dense breast notification, more clients are consulting their GPs about their breast health (as recommended), resulting in increased referrals for supplemental screening and subsequent early detection of interval cancers before they present later as symptomatic cancers.

In summary, the results of this study are consistent with breast density notification driving early detection of breast cancers not detected at the time of mammographic screening.

Reference: Jennifer Stone, Ross Marriott, Marcela Orellana, Emmeline Lee, Gareth Porter. The Impact of Breast Density Notification on Interval Cancer Rates. Journal of Medical Imaging and Radiation Oncology 2026; 0:1–6 https://doi.org/10.1111/1754-9485.70067