Surgery Found to Cut Ovarian Cancer Risk : Health: A 12-year study of nurses reports that those who had their ‘tubes tied’ were 67% less likely to contract the often-fatal illness.

In research that finds a surprising health benefit to tubal ligation, a new study shows that women who have been sterilized by having their “tubes tied” are substantially less likely than other women to develop ovarian cancer.

By following more than 77,500 women over 12 years, epidemiologists at Boston’s Brigham and Women’s Hospital found that those who had surgery to sever their Fallopian tubes were 67% less likely than other women to contract cancer of the ovaries. The researchers also found that hysterectomies seemed to prevent ovarian cancer, although to a lesser extent.

The reason for the reduction is unknown. But the study, published in today’s Journal of the American Medical Assn., is being hailed as an important discovery in the effort to prevent ovarian cancer, which strikes more than 22,000 U.S. women each year and kills more than 13,000 a year.

Although experts do not advise women to rush into surgery solely to prevent ovarian cancer, they say that those who no longer want to have children should seriously consider tubal ligation, especially if they have a family history of ovarian cancer.

“I would rarely recommend anything on the basis of one report, but this report influences me to a considerable degree because it is so well-done,” said Dr. Saul Gusberg, past president of the American Cancer Society and a nationally known expert in gynecological cancer.

Women “should think of tubal ligation as a very excellent form of permanent contraception, with very few if any complications or deficits and now, this important bolstering of their future health,” Gusberg added.

Although it is not nearly as common as cancer of the lung, breast or colon, ovarian cancer is particularly insidious. Often called the silent cancer, it has few warning signs or symptoms until it reaches an advanced stage. Unlike other cancers, there is no good method to screen for ovarian cancer.

More often than not, the disease is fatal. Ovarian cancer causes more deaths than any other cancer of the female reproductive system. An estimated 61% of its victims die within five years of contracting it. By contrast, 22% of women who contract breast cancer die within five years.

Previous research has shown that oral contraceptives, early menopause and childbearing all seem to protect against ovarian cancer. Women who become pregnant at an early age and those who have multiple pregnancies have especially low rates of cancer of the ovaries.

Although several small studies have already hinted at a link between tubal ligation and reduced risk of ovarian cancer, the JAMA article is the first scientific study to demonstrate the connection so convincingly and on such a large scale.

The research is part of the Nurses’ Health Study, a long-running examination of the health of 121,700 female registered nurses who were between the ages of 30 and 55 in 1976, when the study began. About 45,000 of the nurses were excluded from the tubal ligation research because they were already past menopause by the time the study began.

The researchers found that even when they accounted for other factors, such as use of oral contraceptives, women who had undergone tubal ligation were still only one-third as likely to get ovarian cancer.

Although the study simply demonstrated a link, rather than a causal relationship, lead author Susan E. Hankinson said there are several plausible explanations for why tubal ligation would lower cancer rates.

One is that the sterilization could alter the blood flow to the ovaries, somehow changing a woman’s hormonal balance or reducing her rate of ovulation. Previous research has linked hormonal changes and infrequent ovulation with decreased risk of ovarian cancer.

Other studies have suggested that talc, which is contained in gynecological products such as douches and lubricants, contributes to ovarian cancer by enabling carcinogens to enter the intestinal tract. Sometimes, experts say, ovarian cancer begins in the abdominal cavity and spreads to the ovaries. If the Fallopian tubes are cut, these cancer causing agents would have no means of entry.

But the Boston study found that even among women who had never used talc, tubal ligation seemed to prevent ovarian cancer. This suggests some other phenomenon is at work, Hankinson said.

Next to birth control pills, which are used by an estimated 11 million U.S. women, female sterilization--either through tubal ligation or hysterectomy, in which only the uterus is removed--is the second most common form of contraception in the United States. In 1988, the most recent year for which figures were available, 10 million women relied on sterilization

Tubal ligation--the preferred term among doctors is now “tubal sterilization”--involves disconnecting the Fallopian tubes from the ovaries.