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STOCKHOLM – A new study published in JAMA Oncology has revealed that approximately 30% of all breast cancers are detected between scheduled mammography screenings, known as interval cancers. Researchers from Karolinska Institutet analyzed data from half a million women in Stockholm between 1989 and 2020, highlighting the significant proportion of breast cancer cases that emerge outside of regular screening intervals.
Despite advances in mammography technology, the study found that this percentage has remained consistent over the past three decades. “We found that interval cancers account for about 30% of all breast cancers detected by screening and this percentage has remained constant over three decades, despite advances in screening technology,” explained Yuqi Zhang, postdoctoral fellow and lead author of the study.
The research identified several critical risk factors associated with the development of interval cancers. These include:
- High breast density: Increased breast tissue density can make it harder to detect tumors during mammography.
- Hormone therapy: The use of hormone replacement therapy has been linked to an elevated risk of interval cancers.
- Higher education level: This factor was observed to correlate with an increased risk, though the underlying reasons require further investigation.
- Older age at first childbirth: Women who have their first child later in life were found to be at higher risk.
- Family history of breast cancer: Particularly a family history of interval cancer, which significantly increases the risk. Women with a family history of breast cancer were 1.9 times more likely to develop interval cancer, and this risk increased to 2.9 times if they had a family history of interval cancer specifically.
“Women with high breast density and use of hormone therapy are at increased risk of being missed at screening due to false negative results,” Zhang stated.
The study also emphasized that interval cancers are often characterized by rapid tumor growth, making them more challenging to treat. Consequently, the researchers advocate for tailored screening protocols based on individual risk profiles.
“Adapting screening protocols to reflect individual risk profiles—whether through more frequent mammography, supplemental imaging like contrast-enhanced mammography, or incorporating genetic testing—could significantly improve early detection rates,” said Professor Kamila Czene, senior author of the study.
The researchers believe that by implementing more personalized screening strategies, earlier detection and more effective treatments can be achieved, ultimately improving patient outcomes.
Disclaimer: This news article is based on information from a research study and is intended for informational purposes only. It is not a substitute for professional medical advice. Individuals with concerns about breast cancer risk should consult with their healthcare provider to discuss appropriate screening and prevention strategies. The results of this study may not be applicable to all individuals, and further research may be needed to validate these findings.(
More information: Yuqi Zhang et al, Incidence and Risk Factors of Interval and Screen-Detected Breast Cancer, JAMA Oncology (2025). DOI: 10.1001/jamaoncol.2025.0167
