Diethylstilbestrol – A synthetic nonsteroidal estrogen used for palliative treatment of prostatic carcinoma and sometimes advanced breast carcinoma. It was formerly used to relieve vasomotor symptoms associated with menopause, and in primary ovarian failure, female hypogonadism, atrophic vaginitis, kraurosis vulvae, and female castration. Most significantly, however, it was formerly widely used to prevent threatened abortion and premature labor. The female children who were thus exposed to the drug as fetuses have tended to have a variety of cervical abnormalities and an increased risk of clear cell adenocarcinoma of the reproductive tract. Male offspring have sometimes had abnormal genitalia, epididymal cysts, and abnormal semen analyses. Regular examinations and follow-up are indicated for these individuals.