Since implementation of the quality-assured, nationwide digital mammography screening programme in Germany, around twice as many cases of precursor lesions – “ductal carcinoma in situ“ (DCIS) – have been detected as before. At this stage the tumour cells are confined to the mammary ducts in the woman’s breast and have not yet passed the basal membrane, meaning that tumour spreading and the formation of metastases could not yet occur.
“The potential benefit of screening – preventing the development of aggressive breast cancer by means of diagnosing at a preliminary stage and by applying the appropriate therapy – occurs more often among older women than among younger ones,” says Dr. Stefanie Weigel, a lecturer and research assistant at the Institute of Clinical Radiology and the Mammography Reference Centre at Münster University Hospital. The pre-cancerous DCIS cells in 733,905 women who had taken part in the mammography screening programme in North Rhine-Westphalia for the first time between 2005 and 2008 were evaluated with respect to the nuclear grade (high, intermediate and low) and five-year age groups (50 – 69 years). The highest rate of DCIS detection was found for the most aggressive DCIS subtype (high nuclear grade) in the age group 65 and 69 years (0.8 percent per 1,000 women screened versus 0.5 per 1,000 in women of the younger age groups 50 to 64 years). In contrast, the detection of low grade DCIS was only 0.4 per 1,000 women of the oldest age group. The data were collected by the Epidemiological Cancer Register in North Rhine-Westphalia.
The nuclear grade of DCIS is seen as a relevant prognostic factor regarding the likelihood of and duration until tumour invasion may occur with potential development of metastases. Based on current knowledge, DCIS high grade turns into invasive breast cancer after five years on average, while DCIS low grade needs more time (15 years on average). As a result of molecular genetic pathways, DCIS high grade tends to develop into highly aggressive breast cancer.
We conclude that by means of digital mammography screening biologically relevant precursor lesions are more likely to be detected with increasing age before they change into an aggressive, invasive breast cancer. By making a diagnosis at an earlier stage, this systematic early detection of breast cancer leads to a therapeutic benefit, as chemotherapy for invasive cancers of the molecular genetic high-grade pathway can be avoided.
Weigel S, Hense HW, Heidrich J, Berkemeyer S, Heindel W, Heidinger O.
Digital Mammography Screening: Does Age Influence the Detection Rates of Low-, Intermediate-, and High-Grade Ductal Carcinoma in Situ
Radiology. 2016 Mar;278(3):707-13.