The effect of sex hormones on normal breast tissue metabolism: Evaluation by FDG PET/CT

This study investigated the effect of sex hormones on (18)F-fluorodeoxyglucose (FDG) uptake in normal breast tissue. The retrospective study included 249 premenopausal women (median age, 45 years) who were diagnosed with unilateral breast cancer and underwent FDG positron emission tomography/computed tomography and hormone tests. The volume of interest was within the contralateral normal breast and the standardized uptake values (SUVs) were measured. The correlations of sex hormones (including estrogen, progesterone, testosterone, follicle-stimulating hormone [FSH] and luteinizing hormone [LH]) with the SUVs of the normal breast were analyzed. There was a weak negative correlation between age and breast FDG uptake (P = .012, Spearman coefficient = −.16 for the maximum standardized uptake values [SUVmax]), especially in the luteal phase group (P = .005, Spearman coefficient = −.27 for SUVmax). The SUVs of normal breast tissue were increased when progesterone levels were higher (P = .043, Spearman coefficient = .13 for SUVmax). In the irregular menstrual cycle group, FDG uptake in the breast decreased as FSH (P = .027, Spearman coefficient = −.42 for SUVmax) and LH (P = .048, Spearman coefficient = −.44 for SUVmax) increased. Glucose metabolism of normal breast tissue decreases with age, and progesterone weakly affects breast FDG uptake. Gonadotropins may affect breast FDG uptake in premenopausal women with irregular menstrual cycles.