Is 18F-FDG PET/CT Beneficial for Newly Diagnosed Breast Cancer Patients With Low Proportion of ER Expression?

Objective：It is unclear whether the receptor status of breast malignancy is useful in the interpretation of 18F-FDG PET/CT, not to mention the proportion of receptors expression. This study’ purpose was to analyze whether 18F-FDG PET/CT was valuable for helping newly diagnosed breast cancer patients find suspected or unsuspected metastasis lesions based on the proportion of receptors expression. Materials and Methods: 80 newly diagnosed breast cancer patients were divided into six groups, containing N0 (no extraaxillary lymph node metastasis), N1(extraaxillary lymph node metastasis), M0 (no distant metastasis) and M1(distant metastasis) groups, C0(no unsuspected metastasis), C1(unsuspected metastasis and treatment plan changed) detected by PET/CT. The main data including the proportion of receptors ER (estrogen receptor), PR (progesterone receptor), and Her-2(human epidermal growth factor receptor 2) status were extracted. Simple correlation and logistic regression were preformed to analyze the association between them. Results: Patients in N1 group had lower proportion of ER (%) and PR (%) than that in N0 group (ER: 2[0-80] vs. 80[15-95]; PR: 1[0-10] vs. 20 [0-45], p＜0.001). Moreover, the proportion of ER and PR were negatively correlated with N1(ER: [r= -0.339, p= 0.002], PR: [r= -0.247, p= 0.011]) by simple correlation. Also, patients in C1 group had lower proportion of ER (%) and PR (%) than that in C0 group (ER: 10[0-85] vs. 80[15-90], p=0.026; PR: 1[0-10] vs. 20 [0-70], p=0.041)，while the distribution of ER and PR between M1 and M0 group had no significant difference. After the adjustment of traditional factors, the negative correlation between the proportion of ER(OR=0.986, 95%CI of OR[0.972-0.999], p=0.016) and C1 were found by logistic regression , cut-off value were 25% (ER) calculated by ROC(Receiver Operating Characteristic) curve (AUC[Area Under Curve]= 0.647, p=0.024). Conclusion: The proportion of ER in newly diagnosed breast cancer were negatively correlated with unsuspected metastasis detected by 18F-FDG PET/CT. 18F-FDG PET/CT might be recommended for newly diagnosed breast cancer patients with single lesion when the ER expression proportion is less than 25% to find unsuspected metastasis lesions and to modify treatment plan contrasted with conventional imaging and clinical examination.