Role of breast edema in predicting complete response to neoadjuvant chemotherapy in clinical axillary-positive breast cancer.

[BACKGROUND] Breast edema, characterized by increased signal intensity on T2-W sequence of magnetic resonance imaging (MRI), is associated more aggressive tumor biology and worse long-term survival in breast cancer patients.

[PURPOSE] To evaluate the association between types of breast edema and the achievement of pathological complete response (pCR) in the breast and axillary lymph nodes following neoadjuvant chemotherapy (NAC) in patients with breast cancer.

[METHODS] Dynamic breast MRI images before NAC treatment from 561 patients with nonmetastatic, axillary lymph node positive, locally advanced invasive breast cancer were reviewed retrospectively. The location of breast edema was examined on T2W images and classified as peritumoral, subcutaneous (local or diffuse), prepectoral or parasternal. Dynamic T1-W sequences were used to evaluate mass and nonmass lesions, including shape, border characteristics, focality. Radiologic data were integrated with clinicopathological data. In addition, the pathological response to NAC was included in a multivariate logistic regression analysis (P < 0.05).

[RESULTS] All types of edema were significantly associated with pCR in the breast&axilla (combined) (26.9% vs. 17.3%; p = 0.025; OR, 1.8) following NAC. However, no significant association was identified when the presence of edema was separately analyzed in the breast and axilla in relation to NAC response (p = 0.12; OR, 1.4 and p = 0.52; OR, 1.4 respectively). Particularly peritumoral edema was associated with higher pCR rates than other types of edema both in the breast (31% vs. 21%; p = 0.010; OR, 1.8) and in the breast&axilla (29% vs. 16%; p = 0.001; OR, 2.1). Logistic regression identified peritumoral edema as an independent predictor of overall pCR, improving prediction with the breast&axilla response (p = 0.036; OR, 1.7).

[CONCLUSION] The presence of peritumoral edema can predict pCR in the breast&axilla following NAC. Edema assessment could play a crucial role in guiding short-term treatment planning and support closer clinical follow-up.