Can Suspicious Mammography Results Be Clarified with Breast MRI? Can Breast MRI Detect Additional Cancer Foci? Do the Detected Foci Affect Treatment Decisions?

According to a study published in the journal Radiology, breast magnetic resonance imaging (MR = MRI) performed after a mammogram suspicious for breast cancer may detect additional cancer foci in different breast regions, and these detected foci may be more aggressive than the main mass identified by mammography. This may affect the treatment decision. In breast cancer, the most common cancer among women after skin cancers, a prerequisite for good treatment is correct diagnosis and staging, which describes the extent of disease. Breast cancer diagnosis begins with examination of a patient presenting with complaints such as a palpable breast mass, discharge, pain or changes in breast skin. After taking the patient’s history and performing an examination, mammography is performed if there is suspicion, and biopsies from the detected mass or masses are evaluated microscopically by a pathologist to establish the diagnosis. After diagnosis, experienced centers use imaging methods such as magnetic resonance (MR) and PET/CT to determine disease extent. MR is currently one of the most sensitive methods for detecting breast cancer. It is a method used particularly for screening high-risk patients and for preoperative assessment.

Breast MR can detect cancer foci located simultaneously in different breast quadrants (multicentric), which mammography cannot detect, especially in women with dense breast tissue. However, some argue that these additional foci detected by MR are not clinically significant and that these tumors at sites other than the main mass are not substantial enough to affect treatment decisions. It is even debated whether unnecessary detection of these foci by MR could expose the patient to excessive treatment. The opposing view argues for its use because failing to use it could lead to inadequate treatment. Thus, assessment with MR after mammography in breast cancer is controversial. Recently, a study capable of guiding this debate was published in “Radiology” and on the American Society of Clinical Oncology (ASCO) website, providing evidence relevant to the direction of this discussion.

In the study, data from 2021 newly diagnosed women with breast cancer who underwent MR in addition to mammography before surgical planning were evaluated. MR detected foci not identified by mammography in 285 women (14%); 73 of these were in a different quadrant from the mass detected by mammography (multicentric). Of these, 25% were found to be larger than 1 cm, considered the threshold for treatment decisions. In fact, in 17 cases, the additional cancer focus detected by MR was larger than the main mass detected by mammography.

In conclusion, according to this study, multifocal (multicentric) cancers detected by MR after mammography in breast cancer can be substantial enough to affect treatment decisions. This study supports the use of MR in treatment decisions after mammography. However, these findings do not mean that every breast cancer patient should undergo MR. This is a decision for physicians to make following a comprehensive assessment.

Further reading: In which circumstances should breast tissue be assessed with MR imaging?

• Determining silicone implant integrity: It is a useful imaging method for assessing suspected damage to silicone breast implants.
• In the diagnosis of occult primary breast cancer: To detect the main (primary) breast cancer when breast cancer metastasis is found in axillary lymph nodes but the main mass cannot be identified in the breast by USG or mammography,
• To determine disease spread in newly diagnosed breast cancer,
• To assess response to preoperative tumor-shrinking (neoadjuvant) chemotherapy in locally advanced breast cancer,
• When disease recurrence (relapse) is suspected in breast cancer,
• To clarify suspicious mammography findings,
• For screening high-risk patients (those with a positive BRCA mutation or a risk above 20-25% because of a strong family history of breast cancer)
• To detect possible cancer foci not identified by mammography in women with dense breast tissue.