Is digital better?

Introduction

During the changeover from analogue to digital screening in the UK, reassurance is needed to confirm that the outcomes with digital are equal to or better than analogue screening.

Methods

Warwickshire, Solihull & Coventry Breast Screening Service commenced the phased conversion to digital screening in 2005, with a single digital machine on one of three mobiles. This retrospective study compares the screening outcomes of 138,173 women aged between 49 and 70 years screened on analogue or digital imaging between April 2005 and March 2009 inclusive. Approximately one-third of these were screened using digital, the remainder on analogue.

Results

The results show no difference in the rates of screen-detected cancer in prevalent or incident groups between analogue and digital, and rates were stable with time. Similar proportions of invasive and non-invasive cancers were detected in both groups and tumour size was not significantly different. No significant increase in cancer detection in younger compared with older women was seen in the digital group, and digital did not diagnose a higher proportion of lobular cancers. No difference in interval cancer rates between the two methods of screening was seen. On radiological subclassification of interval cancers into normal/benign, uncertain and suspicious, significantly fewer interval cancers were classified as uncertain in the digital than the analogue screening group. See Table 1.

Table 1

Conclusions

These results are reassuring that digital diagnoses similar cancers to analogue screening, and suggest that digital may allow more definitive interval cancer classification.