Endometriosis and Danazol

Danazol - The Common Treatment for Endometriosis May Increase Ovarian Cancer Risk

By Candace Hoffmann

Special to DG News

MIAMI BEACH, FL -- March 19, 2002

Danazol, the long time standard therapy for treating endometriosis, may increase a woman's risk for ovarian cancer.

"This is very worrisome," said Roberta B. Ness, MD, associate professor of epidemiology at the University of Pittsburgh Graduate School of Public Health who presented the findings of a University of Pittsburgh at the 33rd annual meeting of the Society of Gynecologic Oncologists today.

"Our previous studies have found that women with endometriosis are already at a 50 percent increased risk for ovarian cancer [over the general population], and treating them with danazol appears to further increase their risk. This new result, even though it is preliminary, may factor into the equation when clinicians and their patients with endometriosis are deciding on the best treatment," she said.

Dr. Ness, who is also the director of the school's Epidemiology of Women's Health Program, and her colleagues looked at the pooled data of two case-controlled studies conducted between 1993-1999 in the Philadelphia region and in Hawaii/Los Angeles to analyse the relationships among endometriosis, endometriosis treatments and ovarian cancer.

They found that of the nearly 1400 women who were diagnosed with ovarian cancer nearly 10 percent had endometriosis compared to more than 14 percent of the controls. Of those with endometriosis, the 17 women who took danazol were compared to the 15 women taking leuprolide to see if there was any relationship between their respective therapies and ovarian risk. The difference in ovarian cancer occurrence was striking, Dr. Ness said.

Women taking danazol had a 2.7-fold increase in ovarian cancer compared to those who took leuprolide, who had a 1.2-fold risk. "Furthermore, when we looked at duration we did find a duration response relationship and in fact amongst women who had used danazol for four or more months, they had a four-fold increase in ovarian cancer. This dose and duration response relationship was not found among the leuprolide users.

Ovarian cancer, Dr. Ness emphasizes is very rare. According to the American Cancer Society, just over 23,000 women will be diagnosed with ovarian cancer in 2002 compared to 203,500 cases of breast cancer. However, the evidence that endometriosis puts a woman at higher risk for ovarian cancer, and that this study's findings, cause considerable concern.

While this is a very small study, its principal author, Carrie Cottreau, PhD, said in a press release that "the results are telling, and they warrant further studies on a larger scale. The University [of Pittsburgh] is planning on studying the possible link between androgens, such as danazol, and ovarian cancer."

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