Cancer in children, on the other hand, tends to grow more quickly than in adults because children's body tissues generally grow rapidly. A number of cancers affect the endocrine system, either by directly influencing a specific endocrine gland or by producing an uncontrolled supply of hormones. Since hormonal imbalances can affect virtually every organ and body function, hormone-producing tumors can cause a wide range of symptoms. Rare tumors of the male or female gonads may produce inappropriate amounts of virilizing or feminizing hormones. Tumors that are derived from endocrine tissue such as pancreatic islet cells may produce excessive amounts of insulin or related hormones.
Some cancers disrupt the body's functions with the production of hormonelike substances.
Cancers of the breast and prostate frequently possess hormone receptors that allow their growth to be stimulated or retarded by specific hormones. For these cancers, hormone treatment may relieve symptoms. Consequently, men with advanced prostate cancer may be administered estrogen and women with advanced breast cancer may be given estrogen or tamoxifen, a drug that blocks estrogen production and uptake. Studies have shown that tamoxifen treatment may decrease the risk of cancer recurrence even for women whose tumors have negative estrogen receptor tests.