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Researchers Investigate Nasal Spray to Help Prevent Breast Cancer (dateline April 11, 2003)

Inhaling a hormonal regimen may help prevent breast cancer in women at high risk for the disease, according to a study presented at the annual San Antonio Breast Cancer Conference this past December. In the study, women were given a hormonal nasal spray, which halted the production of estrogen in their ovaries and decrease breast density, making breast cancer easier to spot on mammogram films. Although the study results are preliminary, the researchers believe that the nasal spray treatment could help reduce the risk of breast cancer and ovarian cancer in women who have a genetic predisposition to these diseases.

Researchers have found that women who carry mutations of the genes BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) have a significantly higher risk of developing breast cancer and ovarian cancer, compared to women who do not carry these genetic mutations. For BRCA-positive women, removal of the ovaries (oophorectomy) and/or breasts (prophylactic mastectomy) have been shown to reduce the risk of cancer in these areas, although these procedures often have a dramatic impact on a woman’s quality of life. Removing the ovaries results in sterilization while removing the breasts raises physical concerns for many women.

To determine whether an inhaled form of the drug deslorelin, given with small amounts of estrogen and progesterone, reduces the risk of breast cancer while preserving the breasts and ovaries in women who have a genetically high risk for these diseases, lead researcher Dr. Jeffrey Weitzel of the City of Hope Hospital in Duarte, California and colleagues administered the treatment to 13 eligible women.

Already, the researchers have seen a reduction in the women’s breast tissue density. Breast density shows up as white regions on a mammogram film and may mimic breast cancer or other conditions. It may also eclipse breast cancer on a mammogram film or cause radiologists to order additional mammographic views, other breast imaging tests (such as ultrasound), or biopsy to rule out a breast cancer diagnosis. The women’s bone mineral density remained stable during the one-year study, which is important for protecting against osteoporosis.

In addition to reducing breast tissue density, Dr. Weitzel and his team believe that the hormonal nasal spray treatment will reduce the lifetime risk of breast cancer by one third among women with BRCA1 or BRCA2 gene mutations, if the treatment is used for five years, and by more than 70% if used for 15 years. The treatment is also expected to reduce the risk of ovarian cancer.

In the study, the drug deslorelin caused the women’s ovaries to stop functioning, but when the women went off the medicine, their fertility was preserved. The hormones in the nasal spray acted to replace the small amounts of testosterone made by the ovaries, which caused vaginal bleeding similar to that experienced during menstruation. Progesterone was given to help prevent the development of endometrial cancer (cancer of the uterine lining).

Though the study is small and requires duplication in large clinical trials, the researchers believe that the treatment could offer a non-surgical option for women with BRCA1 or BRCA2 gene mutations who are worried about developing breast cancer or ovarian cancer. The treatment is not designed for women who have an average risk of developing breast cancer. However, Dr. Weitzel suggested that the regimen may eventually be offered as a contraceptive.

Additional Resources and References

  • The presentation, "Proof of Principle: Mammographic Density Reduced by a Gonadotropin-Releasing Hormone Agonist (GnRHA)-Based Chemoprevention Regimen For Young Women At High Risk For Breast Cancer," was made at the annual San Antonio Breast Cancer Conference in December 2002,
  • To learn more about genetic risk factors for breast cancer, please visit