Does combined screening with mammography and breast magnetic resonance imaging (MRI) within a 90-day follow-up period offer enhanced breast cancer detection over alternating mammography and MRI screening?
For the study, recently published in the Journal of the American College of Radiology, researchers compared the cancer detection rate (CDR) and sensitivity for 3,810 pairs of combined screening (mammography and breast MRI within 90 days of mammography) and 4,450 pairs of alternating screening (mammography and breast MRI within a 91 to 270-day period after mammography). All reviewed cases were drawn from the Breast Cancer Surveillance Consortium (BCSC), according to the study.
The researchers found that combination screening offered a 96.2 percent sensitivity in contrast to 79.7 percent for MRI and 48.1 percent for mammography.
“As personalized screening increasingly shifts from single to multimodality strategies, revised approaches for evaluating multimodality screening are needed to more accurately reflect screening sequences used in clinical practice,” wrote lead study author Janie M. Lee, M.D., MSc, the director of breast imaging at the Fred Hutchinson Cancer Center and a professor in the Department of Radiology at the University of Washington School of Medicine in Seattle, and colleagues.
Noting that overlapping follow-up periods represent a key challenge with the American College of Radiology (ACR)’s Breast Imaging-Reporting and Data System (BI-RADS) classification system, the researchers employed a truncated follow-up at the subsequent screen, regardless of modality, in order to reduce confusion in evaluating multimodality screening.
Accordingly, they pointed out that the cancer detection rate (CDR) per 1,000 screening examinations for combined screening (13.1) was lower than the sum of the CDRs for MRI (12.3) and mammography (6.8), according to the study authors.
“(This indicated) redundant cancers when each modality was evaluated separately,” said Lee and colleagues. “This approach (with combined screening) also resulted in fewer mammography and MRIs being classified as false-negative, resulting in higher estimates of sensitivity … than with either modality alone.”
Three Key Takeaways
- Increased sensitivity with combined screening. The study found that combined screening (mammography and MRI within 90 days) offered a significantly higher sensitivity (96.2 percent) compared to MRI alone (79.7 percent) and mammography alone (48.1 percent). This suggests that using both modalities together within a 90-day period improves the likelihood of detecting breast cancer.
- Redundancy and cancer detection rates. While the cancer detection rate (CDR) for combined screening was lower (13.1 per 1,000 examinations) than the sum of the CDRs for MRI (12.3) and mammography (6.8) separately, this indicated redundancy in detecting the same cancers when each modality was evaluated independently. Combined screening resulted in fewer false-negative results for both modalities, enhancing the overall effectiveness of detection.
- Implications for multimodality screening evaluation. The study highlighted the need for revised approaches in evaluating multimodality screening, taking into account the sequence of screenings rather than treating each modality as independent. The researchers' approach eliminated overlapping follow-up periods with the goal of facilitating performance audits that reflect clinical outcomes.
The study authors suggested that the ongoing shift of breast cancer screening to a multimodality approach also requires a shift in assessing imaging effectiveness.
“Our analysis identified an important challenge to evaluating multimodality breast cancer screening as strategies rather than as independent modalities, and suggest approaches to address this issue, based on whether screening occurs in combination or alternating sequences,” explained Lee and colleagues. “This approach to evaluating multimodality screening eliminated overlapping follow-up periods which affect performance calculations, with potential for performance audits that more accurately reflect clinical outcomes.”
(Editor’s note: For related content, see “ACR Collaborative Model Leads to 35 Percent Improvement with Mammography Positioning Criteria,” “Leading Breast Radiologists Discuss the USPSTF Breast Cancer Screening Recommendations” and “Breast MRI Study: Can Node-RADS Scoring Enhance Detection of Lymph Node Invasion in Breast Cancer?”)
In regard to study limitations, the authors acknowledged the lack of prospective data for those who had alternating screening prevented the researchers from being able to discern if mammography detection of breast cancer interrupted planned multimodality screening. They also conceded that mammography exams performed at locations external to the BCSC may not have been reflected for 48 percent of the BCSC cohort who were identified as having MRI exams without screening mammograms.
