Digital mammography screening in Germany: Impact of age and histological subtype on program sensitivity

Program sensitivity (PS), i.e., the ratio of screen-detected cancers divided by the sum of screen-detected plus interval cancers, is a major outcome in population-based mammography screening programs (MSP). This study evaluated PS within the digital MSP in Germany focussing on the impact of age and histological subtype.

Data of 838,579 first-time participants aged 50-69 years who were screened in 2005-2008 were linked with cancer registry data from Germany's most populous state, North Rhine-Westphalia. Invasive breast cancers and ductal carcinomas in situ (DCIS) were detected either at screening or during the 24 month post-screening interval. PS was evaluated with respect to age at screening, in-situ or invasive cancer and histological characteristics.

In total, 6767 cancers were detected at screening and 1884 cancers were diagnosed during the post-screening interval. The overall PS amounted to 78.2% and increased from 72.1% at age 50-54 years to 82.4% at age 65-69 years (p for trend <0.0001). PS was higher for non-lobular (79.1%) than lobular carcinomas (72.1%, p < 0.0001). The highest PS was observed in DCIS across all ages (>90%), while PS was lowest among participants aged 50-54 years with invasive breast cancer (67.7%), particularly among those with lobular subtype (62.8%). Interval cancers showed generally more advanced tumour stages.

While overall PS was high, differences across subgroups indicated that youngest screening participants are at higher risk of interval cancer. Age-adapted recall and assessment strategies in younger participants may need to be considered to improve PS in younger women.