Abstract 29P
Background
The heterogeneity of breast tumors might reflect the huge biological complexity and provide a prediction clue for the sensitivity of treatment. Imaging has the potential to non-invasively evaluate the pathologic response and predict prognosis after neoadjuvant chemotherapy (NAC). It is still a challenge to calculate tumor heterogeneity in magnetic resonance imaging (MRI) and build a prediction model based on heterogeneity for pathologic complete response (pCR) after NAC.
Methods
This retrospective study included 217 patients with biopsy-confirmed invasive breast cancer who underwent a pre- and post-NAC MR between June 2014 and September 2018. All patients were randomly (1:1) assigned to the training cohort and validation cohort. MR images were processed by computer algorithms to quantify heterogeneity of tumors. Models including heterogeneity and typical clinical characteristics were constructed to predict pCR. The heterogeneity variation pattern through NAC were classified into four categories: ‘heterogeneity persisted at a high level (abbreviated as H_keep group)’, ‘heterogeneity persisted at a low level (L_keep group)’, ‘heterogeneity rising (rising group)’ and ‘heterogeneity decreasing (decrease group)’.
Results
The average heterogeneity of patients who achieved pCR was significantly lower than that of patients who did not (p=0.029). Through multivariable analysis, the lower heterogeneity was independently associated with pCR (OR, 0.401 [95%CI: 0.21, 0.76]; p=0.007). The heterogeneity combined with clinical characteristics model showed better specificity (0.857 vs. 0.698) and accuracy (0.828 vs. 0.753) than the clinical model. Same results were shown in validation cohort. The survival performance of patients in the L_keep group was the best, while that in the rising group was the worst (p=0.031).
Conclusions
Our study pioneered the quantification of tumor heterogeneity measured through MRI before and after NAC. Patients with lower tumor heterogeneity may be more likely to achieve pCR after NAC. If the tumor kept low-heterogeneous through NAC, it could predict a longer overall survival in contrast to those with heterogeneity rising after NAC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.