HER2-positive breast cancer: 18F-FDG PET for early prediction of response to trastuzumab plus taxane-based neoadjuvant chemotherapy

Purpose

To investigate the value of ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET/CT) to predict a pathological complete response (pCR) after neoadjuvant chemotherapy (NAC) in women with human epidermal growth factor receptor 2 (HER2)-positive breast cancer.

Material and methods

Fifty-seven consecutive women with HER2-positive breast cancer, treated with trastuzumab plus taxane-based NAC, were prospectively included. Maximum Standardized Uptake Value of the primary tumor and axillary nodes were measured at baseline (PET₁.SUV_max) and after the first course of NAC (PET₂.SUV_max). Tumor metabolic volumes were assessed to determine Total Lesion Glycolysis (TLG). The tumor metabolic response (ΔSUV_max and ΔTLG) was calculated.

Results

In univariate analysis, negative hormonal receptor status (p?=?0.04), high tumor grade (p?=?0.03), and low tumor PET ₂ .SUV_max (p?=?0.001) were predictive of pCR. Tumor ΔSUV_max correlated with pCR (p?=?0.03), provided that tumors with low metabolic activity at baseline were excluded. ΔTLG did not correlate with pCR. In multivariate analysis, tumor PET₂.SUV_max?p?=?0.004) with both negative and positive predictive values of 76 %. Although the metabolic features of the primary tumor did not depend on hormonal receptor status, both the baseline metabolism and early response of axillary nodes were higher if estrogen receptors were not expressed (p?=?0.01 and p?=?0.03, respectively).

Conclusion

In HER2-positive breast cancer, very low tumor residual metabolism after the first cycle of NAC (SUV_max?