Breast cancer only visible via MRI is often less aggressive
Cancers only detectable by MRI tend to be smaller and less aggressive than those identified on second-look ultrasound, new data suggest.
Numerous studies have detailed the superiority of MRI in detecting breast cancer lesions that cannot be seen on mammographic or second-look ultrasound (SLUS) exams. The heightened sensitivity is beneficial in that it allows for earlier detection of cancers, but it also presents challenges for providers tasked with managing patients’ care plans, authors of a new paper in the European Journal of Radiology suggest.
“This ‘highest sensitivity’ brings both advantages and disadvantages, as it translates into lesions that were not identified on other imaging modalities but are primarily detected by MRI,” corresponding author Pascal A.T. Baltzer, with the Department of Biomedical Imaging and Image-guided Therapy at the Medical University of Vienna in Austria, and colleagues explain. “The management of these MRI-only lesions is challenging: MRI-guided biopsy or MRI-ultrasound fusion biopsy are resource-intensive and may not be readily available due to a variety of reasons."
Researchers hypothesized that cancers only detectable on MRI might be less aggressive, therefore inflicting less damage on the tissues surrounding tumors. This might make them more difficult to distinguish on SLUS.
To test their theory, the team retrospectively analyzed the cases of 435 patients who underwent breast MRI and SLUS between January 2017 and December 2022. Each patient had at least one lesion confirmed to be malignant and only detectable via MRI. Patients’ demographic characteristics, lesion type, lesion size, histological diagnosis, stage, immunohistochemical analysis, and lymph node status were compared between the two imaging modalities.
The MRI-only lesions were present in around 34% of the patients included, while the rest were detected via SLUS. Lesions in the MRI-only group were significantly smaller (10 mm compared to 20 mm), mostly staged as T1 and displayed characteristics associated with cancers known to be less biologically aggressive compared to those identified on ultrasound. What’s more, lesions detected using SLUS more frequently showed both microscopic and macroscopic axillary metastases.
These findings could change how providers manage lesions that can only be identified by MRI, the group suggests.
“Clinically, these findings are quite relevant,” they note. “The multiple indicators of a lower biological aggressiveness and lower clinical stage would support the idea of primarily follow-up of MRI-suspicious lesions in case of negative SLUS rather than referring patients to a less available test that besides its costs and effort has not a perfect sensitivity.”
Learn more about the research here.
In addition to her background in journalism, Hannah also has patient-facing experience in clinical settings, having spent more than 12 years working as a registered rad tech. She began covering the medical imaging industry for Innovate Healthcare in 2021.