A drug used to treat and prevent breast cancer, Arimidex, can significantly reduce the pain of endometriosis when taken daily along with an oral contraceptive, investigators in the U.S. report.
Endometriosis is an often-painful condition in which tissue that normally lines the uterus is found elsewhere in the abdomen. Current treatments for endometriosis are ineffective for many women or have dangerous side effects, Dr. Serdar E. Bulun, from Northwestern University in Chicago, and his associates note in the medical journal Fertility and Sterility.
Arimidex inhibits an enzyme, aromatase, involved in estrogen synthesis, and it was recently found that high levels of aromatase are expressed in endometrial tissue of women with endometriosis.
Bulun’s group theorized that Arimidex (generic name, anastrozole) would block aromatase from producing estrogen in the endometrial tissue. An oral contraceptive would prevent the osteoporosis associated with aromatase inhibitor drugs.
In their study the investigators treated 18 women, who had failed at least two other treatments for endometriosis, with anastrozole and the Alesse oral contraceptive daily for 6 months.
Fourteen of the 15 women who completed the study experienced significant reductions in pelvic pain. By the end of the first month, the average pain score on a 10-point visual scale fell from 8.70 to 6.20, and by the end of 6 months it was 3.20.
Side effects were mild and improved as the trial progressed. The researchers think that with a longer trial, endometriosis pain and side effects might resolve completely.
The one woman who became pregnant experienced no complications and delivered a normal healthy infant.
“This is an exciting new development in the treatment of a condition with only a limited number of treatments available,” the team concludes.
This study was partially funded by AstraZeneca, the maker of Arimidex.