Comparison of breast cancers detected in the Verona screening program following transition to digital breast tomosynthesis screening with cancers detected at digital mammography screening

Abstract

Background

The Verona population-based breast cancer (BC) screening program provides biennial mammography to women aged 50–69 years. Based on emerging evidence of enhanced detection, the program transitioned to digital breast tomosynthesis (DBT) screening.

Methods

This is a prospective pilot evaluation of DBT with synthesised 2D mammography screening implemented during April 2015–March 2017; the rate and characteristics of cancers detected at DBT screening were compared with those detected at the preceding digital mammography (DM) screening round (April 2013–March 2015) in the same screening program. Distribution of imaging and tumour characteristics were compared.

Results

Amongst 34,071 women screened in the Verona DBT pilot, 315 BCs were detected; 153 BCs were detected amongst 29,360 women in the DM screening round. Estimated CDRs were 9.2/1000 (95% CI 8.3–10.3) DBT screens versus 5.2/1000 (95% CI 4.4–6.1) DM screens, P < 0.001. Statistically significant differences were found in the distribution of whether recall by one/both screen readers (more BCs recalled by both readers at DBT than DM); whether detected on one/two views (higher proportion detected on only one view at DBT than DM); type of radiological lesions; tumour stage, pT and histological categories (lower proportion of DCIS/pTis, higher proportions of pT1a and pT1b, and higher proportion of invasive cancers of special types, at DBT than DM); and tumour grade (higher proportion of grade I at DBT than DM). There were no differences in distributions of nodal and hormone receptor (ER/PR) status.

Conclusions

Our findings provide early insights into the extent that transitioning to DBT screening may modify the characteristics of screen-detected breast cancer to inform discussion regarding pros and cons of DBT screening; although our data provide some reassurance that DBT does not increase the proportion of screen-detected DCIS, they highlight mixed findings on comparative tumour characteristics, suggesting a potential for enhancing screening benefit and possibly also over-diagnosis from DBT screening.

https://ift.tt/2HKRIWR