What is known?
In Australia, interval breast cancers are those diagnosed less than 24 months after having a negative mammography screen. Most interval cancers are typically caused by rapid and aggressive tumour growth.
We used data from a comprehensive survey of more than 3,300 women diagnosed with breast cancer in Queensland between 2010 and 2013.
What is new?
Compared with breast cancers that were detected through symptoms and more than two years after a screening mammogram, interval breast cancers had lower risk of being diagnosed as late stage but had higher risk of being a triple negative cancer.
Among patients who had a negative mammogram before their breast cancer diagnosis, 70% were diagnosed with breast cancer at their next mammogram while 30% were diagnosed with an interval cancer. Women diagnosed with an interval cancer were more likely to have healthy weight, received hormone replacement therapy, conducted monthly breast self-examinations and had previous mammogram in a public facility.
What does this mean?
These results highlight the benefits of mammography screening even among those subsequently diagnosed with an interval cancer. That women who conducted breast self-examinations were more likely to have been diagnosed with an interval cancer than a screen detected cancer may reflect their increased ability to notice symptoms between screening intervals.
Contact: Peter Baade
Reference: Kou K, Cameron J, Youl P, Pyke C, Chambers S, Dunn J, Aitken JF, Baade PD. Severity and risk factors of interval breast cancer in Queensland, Australia: a population-based study. Breast Cancer. 2023. doi: 10.1007/s12282-023-01439-4.