Magnetic Resonance Imaging after Completion of Neoadjuvant Chemotherapy Can Accurately Discriminate between No Residual Carcinoma and Residual Ductal Carcinoma In Situ in Patients with Triple-Negative Breast Cancer

Abstract

BackgroundThe accurate evaluation of favorable response to neoadjuvant chemotherapy (NCT) is critical to determine the extent of surgery. We investigated independent clinicopathological and radiological predictors to discriminate no residual carcinoma (ypT0) from residual ductal carcinoma in situ (ypTis) in breast cancer patients who received NCT.Patients and MethodsParameters of 117 patients attaining pathological complete response (CR) in the breast after NCT between January 2010 and December 2013 were retrospectively evaluated by univariate and multivariate analyses. All patients underwent mammography, ultrasound, and magnetic resonance imaging (MRI) before and after NCT.ResultsThere were 67 (57.3%) patients with ypT0. These patients were associated with hormone receptor-negative status, human epidermal growth factor receptor-2 (HER2)-negative tumors, and a higher likelihood of breast-conservation surgery. Baseline mammographic and MRI presentation of the main lesion, absence of associated microcalcifications, shape, posterior features, and absence of calcifications on ultrasound were significantly associated with ypT0. CR in mammography, ultrasound, or MRI after NCT was also related to ypT0. By multivariate analysis, independent predictors of ypT0 were the triple-negative subtype [Odds ratio (OR), 4.23; 95% confidence interval (CI), 1.11–16.09] and CR in MRI after NCT (OR, 5.23; 95% CI, 1.53–17.85). Stratified analysis by breast cancer subtype demonstrated that MRI well predicted ypT0 in all subtypes except the HER2-positive subtype. In particular, of 40 triple-negative subtypes, 22 showed CR in MRI and 21 (95.5%) were ypT0 after NCT.ConclusionAmong imaging modalities, breast MRI can potentially distinguish between ypT0 and ypTis after NCT, especially in patients with triple-negative breast cancer. This information can help clinicians evaluate tumor response to NCT and plan surgery for breast cancer patients of all subtypes except for those with HER2-enriched tumors after NCT.

Baseline factors predicting a response to neoadjuvant chemotherapy with implications for non-surgical management of triple-negative breast cancer

“…On MRI, the in situ component can present as a non‐mass enhancement. Of 117 patients with TNBC studied by Park et al ,. 67 had ypT0 and 50 ypTis disease after breast surgery.…”

“…Gene expression analysis has revealed that TNBC comprises a heterogeneous group of tumours. Multiple studies have shown that TNBC is more sensitive to neoadjuvant chemotherapy (NACT) than other molecular subtypes, with pathological complete response (pCR) rates of up to 50 per cent. Although TNBC is associated with poor prognosis, with high rates of metastasis and short relapse‐free survival, patients who achieve a pCR on NACT have improved survival and fewer locoregional recurrences than patients with residual disease.…”

“…Most of these did not specify the breast and lymph node status in the definition of pCR, nor the role of residual in situ disease. In a study of 117 patients with TNBC, Park and co‐workers found that 57·3 per cent achieved ypT0 status, whereas 42·7 per cent achieved ypTis (residual ductal carcinoma in situ (DCIS) only). The triple‐negative subtype and complete radiological response on MRI were predictive of ypT0 status, whereas the mammographic and MRI presentations of the primary lesion, and the presence of microcalcifications and residual disease on mammography or ultrasonography after NACT were not.…”

Imaging Considerations and Interprofessional Opportunities in the Care of Breast Cancer Patients in the Neoadjuvant Setting

“…67 Furthermore, MRI may be essential in evaluating axillary lymph node involvement in breast cancer treatments, 68 and in identification of residual ductal carcinoma in situ following NAT. 45,69 One limitation of the quantitative MRI techniques currently available is that there are no multi-site, multi-vendor studies presently validating them. 27 …”

Evaluating the role of magnetic resonance imaging post‐neoadjuvant therapy for breast cancer in the NEONAB trial

“…Nevertheless, our results add to the evidence that, post‐neoadjuvant therapy, MRI is likely more useful for predicting pCR in HER2‐positive tumours, with PPV 100% in this subgroup. Recent evidence also indicates that MRI has higher accuracy with regards to TNBC, but this was not seen in our analysis . This is likely a reflection of the small numbers in our subgroups, but examination of the individual cases also underlines the limitations of MRI in detecting microscopic residual disease.…”