Interval Cancers in Contrast-enhanced Mammography Screening

Introduction to Contrast-enhanced Mammography Screening

Contrast-enhanced Mammography is an emerging functional imaging technique that significantly improves breast cancer detection. However, some patients still develop interval cancers between regular screening rounds. Researchers recently evaluated these specific cases to understand why some tumors remain hidden. This analysis provides vital insights into the performance of screening protocols for high-risk patients. Understanding these outcomes helps clinicians refine their diagnostic approaches for better patient care.

The Interval Cancer Rate in Contrast-enhanced Mammography

A comprehensive study analyzed over 6,900 Contrast-enhanced Mammography examinations conducted over a six-year period. Consequently, they determined that the overall interval cancer rate was 2.29 per 1,000 examinations. Additionally, symptomatic interval cancers occurred much less frequently, with a rate of only 0.82 per 1,000. These results suggest that the modality is highly effective at identifying the majority of malignant lesions during the initial scan. Moreover, these findings offer a benchmark for comparing CEM performance against other modalities like breast MRI.

Furthermore, most interval cancers accounted for only 13% of all diagnosed cancers in the study group. Most of these cancers were retrospectively identified as occult on the prior negative screening. Therefore, even advanced contrast-based imaging has limitations in detecting every nascent tumor. This underscores the importance of patient awareness regarding new symptoms even after a clear report.

Impact of Background Parenchymal Enhancement

The study highlights a significant correlation between background parenchymal enhancement (BPE) and missed invasive cancers. Specifically, 75% of invasive interval cancers appeared in the setting of moderate or marked BPE. In contrast, screen-detected cancers showed these high enhancement patterns in only 30% of cases. Consequently, heavy background enhancement might obscure small or slow-enhancing invasive tumors. Clinicians should therefore interpret scans with high BPE with extra caution to avoid potential misinterpretation.

Most of the missed lesions were categorized as occult rather than misinterpreted. This finding indicates that the tumors were not visible even upon retrospective review by expert radiologists. Consequently, the biological nature of certain cancers might prevent them from accumulating contrast effectively during the early stages. For instance, some low-grade or mucinous carcinomas may demonstrate different enhancement kinetics than aggressive ductal carcinomas.

Frequently Asked Questions

Q1: What is the interval cancer rate for Contrast-enhanced Mammography?

The study found an overall interval cancer rate of 2.29 per 1,000 examinations, which accounts for approximately 13% of all cancers diagnosed in the screening population.

Q2: Why do some invasive cancers remain occult during CEM?

Many invasive interval cancers are associated with moderate or marked background parenchymal enhancement, which can mask the uptake of contrast in malignant tissue.

Q3: Are interval cancers usually due to radiologist error?

No, the majority of interval cancers in this study were classified as occult, meaning they were not visible on the original screening images even during a retrospective double-blind review.

References

1. Amir T et al. Interval Cancers after Negative Screening Contrast-enhanced Mammography. Radiol Imaging Cancer. 2026 May undefined. doi: 10.1148/rycan.250559. PMID: 42065648.
2. Sorin V, et al. Long-Term Study Shows Merits of Contrast-Enhanced Mammography for Women with Higher Breast Cancer Risk. European Journal of Radiology. 2024.
3. Lawson MB, et al. Study Reveals Tradeoffs Between Contrast-Enhanced Mammography and MRI for Supplemental Screening. Radiology. 2023.