Ovary Removal May Cut Cancer Risk
Women who carry genes that increase their risk of breast cancer can sharply reduce their risk by surgical removal of their ovaries, a less disfiguring alternative than preventive removal of both breasts, which has been their primary option until now.
The operation also greatly reduces the risk of ovarian cancer, which is also associated with the same genetic condition.
The new findings offer an alternative but also a new set of difficult choices for women who carry the high-risk versions of the genes, known as BRCA1 and BRCA2.
Between 1 in 400 and 1 in 800 American women carry those genes. The percentage is higher among certain ethnic groups such as Jewish women of Eastern European origin, about 1 in 40 of whom carry the high-risk gene.
Most breast cancers occur in women who do not carry the high-risk genes. But those who do carry those genes have a 50% to 85% risk of developing breast cancer during their lifetime and a 10% to 40% risk of developing ovarian cancer.
The presence of the genes can be readily detected by tests. Doctors do not routinely screen women for the genes, but they are suspected when at least three female members of a family develop breast cancer or when family members develop the disease at an unusually early age.
Removing the ovaries makes the women’s risk of breast cancer comparable to that of women who do not have the mutated genes, according to the new research, which was reported Monday at an Orlando, Fla., meeting of the American Society of Clinical Oncology. The findings also will be reported in Thursday’s New England Journal of Medicine.
The studies support recommending the surgery for women who have finished their childbearing, said Dr. Daniel Haber of Massachusetts General Hospital. It also “provides a strong rationale for genetic testing in women with a strong family history of breast cancer,” he said.
But deciding to undergo the procedure, he added, is ultimately “a highly personal choice.”
The removal of the ovaries almost completely eliminates the risk of ovarian tumors, because there is no tissue left in which cancer can grow.
But the operation also reduces the risk of breast cancer by as much as 75%, because it sharply reduces the body’s production of estrogen, which stimulates breast tumor growth.
“We’ve been doing this [removing ovaries] for a long time, and it makes sense clinically,” said Dr. Jeffrey Weitzel of the City of Hope Medical Center in Duarte. “What hasn’t been clear is whether we truly made an impact by doing this. Now we know that it is likely to be effective if a woman chooses it.”
Removing both breasts to prevent cancer from developing--prophylactic mastectomy--”is the gold standard” for prevention of breast cancer in high-risk women, said Dr. Kenneth Offit of the Memorial Sloan-Kettering Cancer Center in New York, who led one of the new studies. That operation reduces the risk of breast cancer by greater than 90% but does not lower the risk of ovarian cancer.
However, the new studies suggest that ovary removal alone may be sufficient. “It may be that women no longer have to think about making the choice of having their breasts removed,” said Dr. Olufunmilayo Olopade of the University of Chicago Medical Center.
Offit and his colleagues studied 173 women who had been determined to have the mutated version of either the BRCA1 or BRCA2 gene.
The women received extensive genetic counseling and were given the option of either having their ovaries and fallopian tubes removed or undergoing intensive screening for the early detection of ovarian tumors.
One hundred and one of the women chose surgery and 72 chose screening. Three of the women who chose surgery were found to have small ovarian tumors at the time of the surgery and were not included in the final analysis.
At the end of two years, three of the 98 women who chose surgery had developed breast tumors and one had developed a peritoneal tumor, a form of ovarian cancer that arose in the very small amount of tissue left behind in the surgery.
Among the 72 who chose screening, eight developed breast cancer, four developed ovarian cancer and one developed peritoneal cancer.
“This adds to our preventive arsenal, offering women at high risk of these cancers another option for preventing disease,” said Dr. Larry Norton, president of the oncology society.
The second study, led by Olopade, was a retrospective study of 551 high-risk women who had been followed for at least eight years. Of this group, 259 had undergone an operation to remove their ovaries and fallopian tubes and 292 had not.
The team examined the incidence of breast cancer in a subgroup of 99 women who underwent the surgery and 142 who did not.
Of those who underwent surgery, 21% developed breast cancer. Of those who did not have the surgery, 42% developed breast cancer.
The study also showed that the operation greatly reduced the risk of ovarian cancer.
Of the 259 women who had the surgery, six were found to have an ovarian tumor at the time of their operations and two subsequently developed peritoneal tumors.
In sharp contrast, in the group that did not have the operation, 58 developed ovarian cancer.
