Combination of breast imaging parameters obtained from 18F-FDG PET and CT scan can improve the prediction of breast-conserving surgery after neoadjuvant chemotherapy in luminal/HER2-negative breast cancer

Abstract

Introduction: The luminal/Human Epidermal growth factor Receptor 2 (HER2) negative subtype of breast cancer has low chemo-sensitivity. When neoadjuvant chemotherapy (NAC) is indicated in this subtype, before a possible breast-conserving surgery (BCS), it is more reasonable to target tumor shrinkage than complete pathological tumor response. We aimed to identify breast and tumor ¹⁸Fluoro-deoxy-glucose (¹⁸F-FDG) PET-CT scan imaging features for the early prediction of BCS after NAC in luminal/HER2 negative subtypes of breast cancer.

Material and methods: Seventy-seven consecutive women with luminal/HER2-negative breast cancer for whom BCS was initially not feasible and NAC was prescribed, to decrease tumor size before surgery, were included retrospectively. An ¹⁸F-FDG PET-CT scan exam was performed before and after the first course of NAC.

Results: After NAC, 36% (28/77) of women had a mastectomy and 64% (49/77) underwent BCS. Patients with a mastectomy had lower total breast volume (BV_total) (p = 0.002), lower decrease in Δmetabolic tumor volume (ΔMTV) (p = 0.03) and lower SUV_max2 (p = 0.05). Using ROC Curve analyses to define the optimal predictive threshold of BV_total (496 cm³) and ΔMTV (-17.1%), 3 subgroups of women with different odds of BCS after treatment were identified (p = 0.001): low, medium and high probability groups (respectively 29%, 62% and 82%).

Conclusions: For patients with Luminal/HER2 negative breast cancer, the combination of the imaging features of the tumor and the mammary gland, obtained with ¹⁸F-FDG PET-CT at baseline and after the first cycle of NAC, may allow the physician to evaluate the probability of BCS.

Keywords: Breast cancer; Chemotherapy; PET-CT; Surgery.