FDA Panel Backs Contraceptive’s Approval : Medicine: An injection of Depo-Provera provides protection for 3 months. Researchers discount past concerns of increased cancer risks.

A federal advisory panel recommended Friday that the government approve Depo-Provera, a highly effective but controversial contraceptive that provides three months of protection with a single injection.

The drug, manufactured by the Upjohn Co. of Kalamazoo, Mich., already is marketed in more than 90 countries--including the United Kingdom, Germany, France, New Zealand, Norway, Belgium and Sweden--and has been used by an estimated 30 million women worldwide.

But it has repeatedly failed to win approval in this country for the past 25 years because of concerns, raised in animal studies, that the drug increased the risk of breast and other cancers.

Members of the Food and Drug Administration’s advisory committee on fertility and maternal health drugs said they found the evidence from years of use abroad compelling enough to recommend that the drug finally be licensed here.

A series of studies conducted by the World Health Organization on more than 11,000 women have shown that the risk of breast cancer appears to be no greater than that associated with birth control pills.

“When it has been used in 90 countries and used by so many millions of women--if it caused anything dramatic, we’d have some clues,” said Dr. Barbara S. Hulka, chairwoman of the panel and a professor of epidemiology at the University of North Carolina School of Public Health.

“We don’t see any clues of any serious effects,” she added. “The WHO study was . . . reassuring.”

The agency is not bound by the recommendations of its advisory committees, but rarely overrules their advice.

“The company is very pleased at the outcome” of the panel deliberations, said Dr. Joann L. Data, an Upjohn vice president. “We feel quite positive about this drug. We support it currently around the world.”

The last contraceptive approved by the FDA was in December, 1990, when the agency licensed Norplant, a fan-like arrangement of six silicone rubber capsules implanted under the skin. Norplant releases a hormone that prevents pregnancy for up to five years. The agency also is deliberating over whether to approve the vaginal condom, a pouch-like barrier device.

Depo-Provera contains the drug medroxyprogesterone acetate, a synthetic progestogen similar in chemical structure to natural progesterone. It inhibits ovulation by suppressing the hormones secreted by the pituitary gland that stimulate the release of a mature egg.

The drug was estimated by one physician at the meeting to cost about $120 a year, considered modest for a contraceptive.

Its side effects include weight gain, absence of menstrual periods and delayed fertility once the drug is stopped.

Some studies have also shown a connection to osteoporosis and low birth weight associated with accidental pregnancies. The committee called for additional research into these problems.

The drug already is available in the United States for the treatment of renal and endometrial cancer.

Concerns about Depo-Provera arose years ago after studies showed that it caused both malignant and benign breast tumors in beagles. But researchers have since concluded that beagles were not appropriate for studying the drug, and the results have been discounted.

Opponents also have worried that the drug could be abused in institutions and other facilities caring for the mentally retarded and other special populations.

“We are . . . concerned that Depo-Provera . . . will be selectively offered, that women with the least power in our society will be encouraged and possibly coerced” into using the drug, said Cindy Pearson of the National Women’s Health Network.

The World Health Organization studies were initiated in 1979 to determine whether Depo-Provera increased the risk of five types of cancer--breast, liver, ovarian, cervical and endometrial. They involved 11,890 women from Nairobi, Mexico City, Bangkok and Chang Mai, Thailand.

The studies showed the overall risk for all of the cancers was not increased, and that the drug appears to have a protective influence against endometrial cancer.

But the studies did show an elevated risk of breast cancer among women under the age of 35 during their first four years using the drug. Researchers have speculated that the drug could be a “weak promoter” of tumors already in development.

“My own personal interpretation is that these increased risks are not likely to represent new tumors that wouldn’t have occurred anyway,” said Dr. David Thomas, professor and head of the department of epidemiology at Fred Hutchinson Cancer Research Center in Seattle, who presented the WHO data.

Breast cancer risk did not rise with prolonged use of the drug and did not increase among those women who had been using the drug for more than five years, according to the study.

Numerous medical, family planning and reproductive organizations--including the American Medical Assn., the Allan Guttmacher Institute and the International Planned Parenthood Federation--urged the panel to recommend that the drug be approved.

“Clinical experience over the past three decades has been vast,” said Dr. Louise B. Tyrer, medical director of the Assn. of Reproductive Health Professionals. “We believe it deserves to be added to the contraceptive choices available to women in the United States.”

But several organizations, including the National Women’s Health Network, the National Latina Health Organization and the National Black Women’s Health Project, warned the committee that research on the drug was still too questionable.

“We believe that the proper reaction . . . is to neither dismiss the increased risk identified . . . for young women, nor to assume that the lack of risk found for older users is conclusively demonstrated,” said Pearson of the women’s health network.