VOLUME 37, NO. 20, May 22, 2001
Tubal ligation cuts risk of ovarian CA in high-risk women
TORONTO – Women at high risk for developing ovarian cancer can decrease that risk by 60% by having a tubal ligation, researchers here concluded.
The study, published in the Lancet (May 12, 2001), also found that women who had used oral contraceptives before their tubal ligation had an even greater reduction in risk (72%).
"Until now, I have been advising high-risk women to have their ovaries removed at age 35, but that comes with all the side-effects of surgical menopause," said Dr. Steven Narod, a medical geneticist at Sunnybrook and Women's College Health Sciences Centre, and the lead author of the study.
Because of this, he said, fewer women choose to have oophorectomy before age 35. But offering tubal ligation as soon as childbearing is complete is a reasonable alternative and can be followed later by an oophorectomy.
Aside from prophylactic oophorectomy, other strategies for reducing the risk of ovarian cancer include chemoprevention with oral contraceptives, and regular ultrasound screening.
However, the effectiveness of ultrasound screening has not been established, and there are concerns that oral contraceptive (OC) use could be associated with an increased risk of breast cancer, he explained.
Women are considered to be at high risk for developing ovarian cancer if they have a mutation in either the BRCA1 or BRCA2 genes, said Dr. Narod, who was one of the researchers behind the discovery of the BRCA1 gene.
For carriers of BRCA1 mutations, the risk of developing ovarian cancer is about 40%, and for BRCA2 carriers, it is about 25%.
However, the protective effect of tubal ligation was only apparent in BRCA1 carriers, he said.
"We don't fully understand why this is, but because of this we cannot yet make specific recommendations for carriers of BRCA2."
The study involved women from Canada, the U.S. and the U.K. who carried a pathogenic mutation in their BRCA1 or BRCA2 genes.
Two hundred and thirty-two of these women, who had a history of invasive ovarian cancer, were compared with 232 controls, who had the same genetic mutation but did not have cancer.
The matching was for year of birth, country of residence, parity and history of oral contraception and breast cancer.
Among the 173 patients and controls who had the BRCA1 mutation, tubal ligation was much less common among the women with ovarian cancer (18%) than among those without (35%).
The researchers concluded that the relative risk of ovarian cancer after tubal ligation decreased by 60%, and by 72% for women who had tubal ligation and a history of OC use.
"This is very practical information that we can give patients. They come in for their genetic testing on Monday, get their tubal ligation on Tuesday and their risk of ovarian cancer is reduced by 60% on Wednesday," said Dr. Narod.
The study found the greatest protection from tubal ligation when the procedure was done before age 30. However, Dr. Narod said he would still recommend an oophorectomy in the future.
Not only does this offer her further protection against ovarian cancer, but it is also a safeguard against breast cancer, another risk for women with the BRCA1 mutation, he said.
AACR Abstract #R1551, 2003
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