Gestational trophoblastic disease

What is gestational trophoblastic disease? Cancer starts when cells in the body begin to grow out of control. Cells in nearly any part of the body can become cancer, and can spread to other areas of the body. To learn more about how cancers start and spread, see What Is Cancer? Gestational trophoblastic (jeh-STAY-shuh-nul troh-fuh-BLAS-tik) disease (GTD) is a group of rare tumors that involve abnormal growth of cells inside a woman's uterus. GTD does not develop from cells of the uterus like cervical cancer or endometrial (uterine lining) cancer do. Instead, these tumors start in the cells that would normally develop into the placenta during pregnancy. (The term gestational refers to pregnancy.) GTD begins in the layer of cells called the trophoblast (troh-fuh-BLAST) that normally surrounds an embryo. (Tropho- means nutrition, and -blast means bud or early developmental cell.) Early in normal development, the cells of the trophoblast form tiny, finger-like projections known as villi. The villi grow into the lining of the uterus. In time, the trophoblast layer develops into the placenta, the organ that protects and nourishes the growing fetus.