Digital compared to screen-film mammography: breast cancer prognostic features in an organized screening program

Abstract

Our previous study found cancer detection rates were equivalent for direct radiography compared to screen-film mammography, while rates for computed radiography were significantly lower. This study compares prognostic features of invasive breast cancers by type of mammography. Approved by the University of Toronto Research Ethics Board, this study identified invasive breast cancers diagnosed among concurrent cohorts of women aged 50-74 screened by direct radiography, computed radiography, or screen-film mammography from January 1, 2008 to December 31, 2009. During the study period, 816,232 mammograms were performed on 668,418 women, and 3,323 invasive breast cancers were diagnosed. Of 2,642 eligible women contacted, 2,041 participated (77.3 %). The final sample size for analysis included 1,405 screen-detected and 418 interval cancers (diagnosed within 24 months of a negative screening mammogram). Polytomous logistic regression was performed to evaluate the association between tumour characteristics and type of mammography, and between tumour characteristics and detection method. Odds ratios (OR) and 95 % confidence intervals (CI) were recorded. Cancers detected by computed radiography compared to screen-film mammography were significantly more likely to be lymph node positive (OR 1.94, 95 %CI 1.01-3.73) and have higher stage (II:I, OR 2.14, 95 %CI 1.11-4.13 and III/IV:I, OR 2.97, 95 %CI 1.02-8.59). Compared to screen-film mammography, significantly more cancers detected by direct radiography (OR 1.64, 95 %CI 1.12-2.38) were lymph node positive. Interval cancers had worse prognostic features compared to screen-detected cancers, irrespective of mammography type. Screening with computed radiography may lead to the detection of cancers with a less favourable stage distribution compared to screen-film mammography that may reflect a delayed diagnosis. Screening programs should re-evaluate their use of computed radiography for breast screening.

Detection Rate, Recall Rate, and Positive Predictive Value of Digital Compared to Screen-Film Mammography in the Quebec Population-Based Breast Cancer Screening Program

“…This large study of concurrent cohorts reported results different from ours concerning CR; they show a statistically significant 21% lower detection rate and no statistically significant difference in recall rate for CR compared to SFM. Moreover, they found that cancers detected by CR compared to SFM were significantly more likely to be lymph node positive and have a higher stage [35]. In our data, there was little or no difference in detection rate and higher recall rate in CR compared to SFM.…”

Digital Compared with Screen-Film Mammography: Measures of Diagnostic Accuracy among Women Screened in the Ontario Breast Screening Program

“…Evidence from large randomized controlled trials and concurrent cohort studies suggest that DR is at least equivalent to SFM in cancer detection and may offer improved detection for ductal carcinoma in situ (DCIS) and among young women with dense breasts (3-10). However, our previous studies have shown that breast screening with CR mammography may result in significantly lower cancer detection and has the potential for delayed diagnosis (10,11).…”