Approximately 30% of ER-positive breast cancer will unfortunately display primary resistance to hormonal therapy, and some may develop acquired resistance to the therapy after initial treatment. Hypoxia is a normal phenomenon in solid tumors that arises, in part, from uncontrolled proliferation and immature blood vessels. Previous studies have demonstrated hypoxia significantly reduced both the growth-promoting effects of estradiol (E2) and the growth-inhibitory effects of an antiestrogen on ER-positive breast cancer cell lines. A recent study comparing neoadjuvant letrozole with letrozole plus metronomic cyclophosphamide found that increased levels of HIF-1a were significantly associated with resistance to treatment. Taken together, these data indicate that hypoxia might be associated with endocrine resistance in breast cancer.~With PET/CT, radiolabeled hypoxia-avid compounds can be applied to evaluate oxygenation status in experimental or human tumors. 18F-labeled fluoromisonidazole (1-[2-nitro- 1-imidazolyl]-2-hydroxy-3-fluoropropane [18F-FMISO]) PET/CT is the most widely used one in the clinic. Studies have demonstrated an excellent correlation between the 18F-FMISO uptake and oxygenation status of several cancers including breast cancer.~The major aim of our study was to analyze uptake of 18FFMISO as well as the IHC expression of HIF-1-alpha in ER-positive breast cancers, and to predict the clinical, pathological and biological response of primary endocrine therapy.
The aim of our current study was to analyze whether 18F-labeled Fluoromisonidazole (1-(2-nitro-1-imidazolyl)- 2-hydroxy-3-fluoropropane [18F-FMISO]) PET/CT and expression of HIF-1-alpha could predict response of primary endocrine therapy in ER-positive breast cancer