PGR and breast cancer: There was no significant correlation of serum DKK-1 levels with age (P = 0.61), histological type (P = 0.11), expression of ER (P = 0.09), expression of PR (P = 0.12), family history of breast cancer (P = 0.07), radiation therapy (P = 0.39), chemotherapy (P = 0.31), and menopausal status (P = 0.45).