Which of the following is true regarding male breast cancer?

Fewer than 1% of all breast cancers occur in men. Male breast cancer is preceded by gynecomastia in 20% of men. It is associated with radiation exposure, estrogen therapy, testicular feminizing syndromes, and Klinefelter's syndrome (XXY). Breast cancer is rarely seen in young males and has a peak incidence in the sixth decade of life. DCIS makes up 85%. The treatment of male breast cancer is surgical, with the most common procedure being a modified radical mastectomy. Ref: Wilhelm MC, Langenburg SE, et al: Cancer of the male breast, in Bland KI, Copeland EM III (eds): The Breast: Comprehensive Management of Benign and Malignant Diseases. Philadelphia: WB Saunders, 1998, p 1416.