GnRH Agonist Regimen May Reduce Breast Cancer Risk.

SAN ANTONIO -- A GnRH agonist-based hormonal chemo-prevention regimen shows early promise in young women who are at high risk for breast cancer, Dr. Jeffrey N. Weitzel reported at a breast cancer symposium sponsored by the San Antonio Cancer Institute.

The prototype regimen consists of a 100-uL nasal spray containing 1 mg of the GnRH agonist deslorelin self-administered each morning along with 0.3 mg of estradiol and 0.275 mg of testosterone delivered via another 100-uL nasal spray every morning. In addition, 10 mg/day oral medroxyprogesterone acetate is given for 14 consecutive days every 12 weeks.

This chemoprevention regimen is designed to reduce breast cell proliferation and decrease the typically high mammographic density of young women's breasts so mammography becomes a useful surveillance tool for the detection of early breast cancer in this young, high-risk population, explained Dr. Weitzel of the City of Hope National Medical Center, Duarte, Calif.

More specifically, this dose of the GnRH agonist is intended to induce a reversible medical oophorectomy by suppressing ovarian function to post-menopausal levels while preserving a woman's reproductive options. Early bilateral surgical oophorectomy has been shown to sharply decrease breast cancer risk, he noted.

The ultralow dose of estrogen utilized in this chemoprevention regimen entails less estrogen exposure than at any other time during a woman's normal menstrual cycle. Yet ...