OBJECTIVETo evaluate the role and the performance of diffusion weighted imaging (DWI) for predicting the early response to neoadjuvant chemotherapy (NAC) in local advanced breast cancer (LABC) and to assess the accuracy of DWI in evaluating residual lesion after NAC.

METHODS88 women with LABC (89 lesions) underwent DWI before and after the first and final cycle of NAC. For each patient, the apparent diffusion coefficient (ADC) values were compared between the baseline and follow-up to predict the early response to NAC. The residual tumor volumes were obtained using 3D maximum intensity projections (MIP) of DWI map, and were compared with pathological findings to assess the accuracy of DWI in detecting and measuring residual tumor. All results were proved or analyzed comparing with the data from histopathology.

RESULTSThere were 68 lesions responding to NAC, while 21 non-responders. The baseline ADC values of responders and non-responders were (1.049 +/- 0.135) x 10(-3) mm(2)/s and (1.171 +/- 0.134) x 10(-3)mm(2)/s, respectively, with a significant difference (t = -2.731, P = 0.009 < 0.01). The ADC value measured prior to treatment was (1.087 +/- 0.146) x 10(-3)mm(2)/s, and the degree of the changes in tumor volume after NAC was (70.4% +/- 55.1)%. A negative correlation was observed (r = -0.430, P = 0.025 < 0.05). In the response group, there was a significant difference in ADC value between prior to NAC and 1st cycle of NAC, the final cycle of NAC, respectively (P < 0.001). While no significant differences were found in non-responders during NAC (P > 0.05). The tumor volume correlation coefficient between DWI and pathology measurements was very high (r = 0.749, P < 0.01).

CONCLUSIONDWI appears to provide functional information regarding changes in ADC value of tumors due to NAC. DWI may be useful in monitoring the early pathological response of tumor after the initiation of treatment and in evaluating the residual tumor after NAC.