Although far more common in women, breast cancer can also develop in men. Before puberty, the breas...
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Although far more common in women, breast cancer can also develop in men. Before puberty, the breast tissue in boys and girls is similar. In girls, female hormones produced at puberty cause the growth of milk-producing glands called lobules and tiny tubes called ducts, which carry milk from the lobules to the nipple and an increase in fat and connective tissue called stroma. Male hormones restrict further growth of the breasts after puberty; the tissue contains ducts but few or no lobules. The duct cells in a man can undergo cancerous changes, but breast cancer is less common because these cells are less developed. Also, the male breast tissue is not exposed to the female hormone estrogen, as women's breast tissue is. Factors that increase the risk of breast cancer in men include increased age, exposure to estrogen, and very low levels of the male hormone, testosterone.