An important paper appeared earlier this week in JAMA Network Open in which the authors compared the mortality among women with screening-detected breast cancers vs IBCs. Recognising that an IBC has a worse prognosis, the authors sought to establish whether the length of the inter-screening period might influence prognosis and mortality. Their cohort consisted of 3,019 post-menopausal women with breast cancer, of whom 35% were IBCs and 65% were detected at the time of screening. The IBCs were then subdivided into those occurring less than 1 year or between 1 and 2.5 years after the last mammogram mandated by protocol.
Their findings were statistically significant. IBCs diagnosed within 1 year of a negative screening mammogram had larger tumour sizes, were more advanced clinically and had greater lymph node involvement than cancers detected by screening. As seen at left (© JAMA), the breast cancer-specific mortality for IBCs less than 1 year was significantly higher than IBCs detected between 1 and 2.5 years and compared to breast cancers detected by screening.
The authors highlighted a number of strengths in their study, including: a large and diverse population of patients; a longitudinal cohort following a screening programme for at least 10 years; an extensive follow-up period; and the ability to stratify by annual or biennial screening intervals. However, they also acknowledged a limitation in that they were unable to differentiate true IBCs from cancers that were not detected by screening (i.e. false negatives).
The authors stated, “Interval cancers occurring within 1 year from a mammogram with negative results may have a unique biology that accounts for aggressive features.” They also concluded, “This study adds to the growing body of literature that argues for the development of novel approaches to detect life-threatening cancers currently missed by mammographic screening.” At CapeRay we believe that dual-modality systems which integrate X-rays and ultrasound represent one such novel approach to screening.