E2572. Predicting Disease Recurrence Using Pretreatment Imaging in Primary ER-Negative, HER2-Positive Breast Cancer
  1. Hiroko Tsukada; Tokyo Women's Medical University
  2. Jitsuro Tsukada; Keio University School of Medicine
  3. Yumi Shimizu; Tokyo Women's Medical University
  4. Keio Natori; Tokyo Women's Medical University
  5. Eiichiro Noguchi; Tokyo Women's Medical University
  6. Sadako Akashi; Tokyo Women's Medical University
Prediction of prognosis prior to the treatment initiation is important to determine the treatment strategy in breast cancer. Previous studies have suggested that Magnetic Resonance Imaging (MRI) findings of not only the tumor itself but also peritumor tissues may be related to malignancy, treatment response, and prognosis. 18F-fluorodeoxyglucose (FDG) Positron Emission Tomography-Computed Tomography (PET/CT) has also been reported to be useful in predicting the treatment response and prognosis in human epidermal growth factor receptor 2 (HER2)-positive breast cancer. In this study, we examined whether the parameters obtained from pretreatment images could be predictors of recurrence-free survival (RFS) in stage I/II estrogen receptor (ER)-negative, HER2-positive breast cancer.

Materials and Methods:
Patient/tumor chracteristics, and parameters obtained from pretreatment images were evaluated in a Cox regression proportional hazards model in 124 patients with stage I/II ER-negative, HER2-positive breast cancer between January 2008 and August 2019 who underwent MRI or PET/CT before starting treatment. In addition to tumor morphology, MRI findings including peritumor edema using T2-weighted image (T2WI) sequences, and intra-tumor and peritumoral (ADC) values, and their ratios (peritumoral ADC/intratumoral ADC: p/t ratio) were evaluated. From PET/CT images, FDG accumulation within the tumor (maximum standardized uptake value: [SUVmax] was evaluated.

Twenty-six patients received neoadjuvant chemotherapy, and 9 (34.6%) achieved pathologic complete response (pCR). The mean observation period was 90 months, with 18 (14.5%) recurrences and 8 (6.5%) deaths. Among the factors associated with RFS in univariate analysis, tumor growth orientation, presence of peritumor edema, p/t ratio on MRI, and SUVmax on PET CT were considered as multivariate analysis factors in consideration of collinearity. Multivariate analysis revealed that high p/t ratio (HR 6.0 [95% CI 3.1 - 11.7], p < 0.01) were independent predictors of tumor recurrence.

In stage I/II ER-negative, HER2-positive breast cancer, high p/t ratio obtained by pretreatment MRI might be an independent predictors of tumor recurrence.