Interval Breast Cancer Rates and Tumor Characteristics in the Prospective Population-based Malmö Breast Tomosynthesis Screening Trial

Abstract

Background: Interval cancer rates can be used to evaluate whether screening with digital breast tomosynthesis (DBT) contributes to a screening benefit. Purpose:To compare interval cancer rates and tumor characteristics in DBT screening to those in a contemporary population screened with digital mammography (DM). Materials and Methods:The prospective population-based Malmö Breast Tomosynthesis Screening Trial (MBTST) was designed to compare one-view DBT to two-view DM in breast cancer detection. The interval cancer rates and cancer characteristics in the MBTST were compared with an age-matched contemporary control group, screened with two-view DM at the same center. Conditional logistic regression was used for data analysis.Results: There were 14 848 women who were screened with DBT and DM in the MBTST between January 2010 and February 2015. The trial women were matched with two women of the same age and screening occasion at DM screening during the same period. Matches for 13 369 trial women (mean age, 56 years  10 [standard deviation]) were found with 26 738 women in the control group (mean age, 56 years  10). The interval cancer rate in the MBTST was 1.6 per 1000 screened women (21 of 13 369; 95% CI: 1.0, 2.4) compared with 2.8 per 1000 screened women in the control group (76 of 26 738 [95% CI: 2.2, 3.6]; conditional odds ratio, 0.6 [95% CI: 0.3, 0.9]; P = .02). The invasive interval cancers in the MBTST and in the control group showed in general high and 75% [54 of 72]), and low proportions of luminal A-like subtype (26% [five of 19] and 17% [12 of 72]), respectively. Conclusion:The reduced interval cancer rate after screening with digital breast tomosynthesis compared with a contemporary agematched control group screened with digital mammography might translate into screening benefits. Interval cancers in the trial generally had nonfavorable characteristics.

Digital Breast Tomosynthesis: Potential Benefits in Routine Clinical Practice

“…24 A prospective, population-based screening trial (Malmo Breast Tomosynthesis Screening Trial) compared with a large contemporary control group screened with digital mammography showed a lower interval cancer detection rate. 25 These results are concordant with other previous published studies. 26,27 The interval cancers' characteristics (i.e., the proportion of invasive, size, grade, and nodal status) with DBT screening were similar to those identified in previous DM-only rounds.…”

True and Missed Interval Cancer in Organized Mammographic Screening: A Retrospective Review Study of Diagnostic and Prior Screening Mammograms

“…When an increase in cancer detection at screening is observed, a decrease in interval cancer rate is anticipated. To date, among the few studies reporting interval cancer rates after screening with DBT+DM/SM, only MBTST has demonstrated a statistically significant interval cancer reduction, otherwise no statistically significant differences were observed (Table 1.6) (104,157,(159)(160)(161)(162)(163)(164)(165) . A recent meta-analysis of five European studies demonstrated a pooled difference in interval cancer rates for DBT versus DM of -0.15/1000 (95% CI -0.59 -0.29) (166).…”

“…In contrast, most other prospective non-randomized studies were based on sequential reading of DBT and DM images from the same women (39,45,60,62,156). In the studies from Oslo (OTST) and Malmö (MBTST), four different radiologists performed screen-reading of each exam, followed by a consensus meeting including all images, a design that might potentially have increased the cancer detection as well as reduced the interval cancer rates (158,165). In the STORM studies, sequential reading was performed by the same radiologist, and women were recalled if screen-reading was positive in either step, which may also have biased the results in favor of DBT (45,62).…”

Breast Density and Risk of Interval Cancers: The Effect of Annual Versus Biennial Screening Mammography Policies in Canada

“…35 The most recent screening tomosynthesis study of a 5-year period found an ICR of 1.6 per 1000 screened women, compared with 2.8 per 1000 screened women in the control group. 74 Recalls are highest in prevalence scans for any modality, and with supplemental US, recalls reported at 15.1%, decreased to 7.4% in subsequent scans. 62 Similarly with supplemental MRI screening, there were higher recalls of 9.5% in the DENSE trial in the prevalence scans which decreased to 3.2% on incidence screening.…”