Effects of Neoadjuvant Chemotherapy on Benign Breast Lesions Compared to Cancers: Should an Additional Lesion on Magnetic Resonance Imaging Responding Similar to Cancer after Neoadjuvant Chemotherapy be Viewed with Suspicion?

Neoadjuvan kemoterapinin olası benign meme lezyonları üzerindeki etkilerinin MRG ile değerlendirilmesi: İki olgu sunumu

In cases with breast cancer, probably benign lesions can also be seen in the other areas of the breast. It is known that neoadjuvant chemotherapy causes morphological changes in the normal breast tissue and the benign lesions, in addition to effects on malignant mass. In cases with complete response with neoadjuvant chemotherapy, probably benign lesions without tissue diagnosis cause a dilemma in the breast conserving surgery plan, when they shrink or disappear at the end of the treatment. We aimed to demonstrate the effects of neoadjuvant chemotherapy in cases with probably benign breast lesions via dynamic contrast enhanced breast MRI.

Breast MRI for Evaluation of Response to Neoadjuvant Therapy

Neoadjuvant therapy is increasingly being used to treat early-stage triple-negative and human epidermal growth factor 2-overexpressing breast cancers, as well as locally advanced and inflammatory breast cancers. The rationales for neoadjuvant therapy are to shrink tumor size and potentially decrease the extent of surgery, to serve as an in vivo test of response to therapy, and to reveal prognostic information for the patient. MRI is the most accurate modality to demonstrate response to therapy and to help ensure accurate presurgical planning. Changes in lesion diameter, volume, and enhancement are used to predict complete response, partial response, or nonresponse to therapy. However, residual disease may be overestimated or underestimated at MRI. Fibrosis, necrotic tumors, and residual benign masses may be causes of overestimation of residual disease. Nonmass lesions, invasive lobular carcinoma, hormone receptor-positive tumors, nonconcentric shrinkage patterns, the use of antiangiogenic therapy, and late-enhancing foci may be causes of underestimation of residual disease. In patients with known axillary lymph node metastasis, neoadjuvant therapy may be followed by targeted axillary dissection to avoid the potential morbidity associated with an axillary lymph node dissection. Diffusion-weighted imaging, radiomics, machine learning, and deep learning methods are under investigation to improve MRI accuracy in predicting treatment response.^©RSNA, 2021.

Frequency and Outcomes of New Suspicious Lesions on Breast MRI in the Setting of Neoadjuvant Therapy

OBJECTIVE. The purpose of this article was to determine the frequency and outcomes of new suspicious findings on breast MRI after initiation of neoadjuvant therapy. MATERIALS AND METHODS. A retrospective database review identified all breast MRI examinations performed to assess response to neoadjuvant therapy between 2010 and 2018. Cases with new suspicious lesions assessed as BI-RADS 4 or 5 and found after the initiation of neoadjuvant treatment were included. Cases with no pretreatment MRI, cases in which the suspicious lesion was present on the baseline MRI but remained suspicious, and cases with insufficient follow-up were excluded. Radiologic, pathologic, and surgical reports were reviewed. Malignant outcomes were determined by pathologic examination. Benignity was established by pathologic examination, follow-up imaging, or both. A total of 419 breast MRI examinations in 297 women were performed to assess response to neoadjuvant therapy. After exclusions, 23 MRI examinations (5.5%) with new suspicious findings, all assessed as BI-RADS 4, comprised the final cohort. RESULTS. Of the 23 lesions, 13 new suspicious findings (56.5%) were contralateral to the known malignancy, nine (39.1%) were ipsilateral, and one (4.3%) involved the bilateral breasts. Lesion types included mass (16, 69.6%), nonmass enhancement (5, 21.7%) and focus (2, 8.7%). None of the new suspicious findings were malignant. CONCLUSION. New suspicious findings occurred in 5.5% of breast MRI examinations performed to monitor response to neoadjuvant therapy, and none of these new lesions were malignant. Our findings suggest that new lesions that arise in the setting of neoadjuvant therapy are highly unlikely to represent a new site of malignancy, particularly if the index malignancy shows treatment response. Larger studies are needed to confirm whether biopsy may be safely averted in this scenario.