Preventive Mastectomy Lowers Cancer Risk

Preventive Mastectomy Lowers Cancer Risk Feb. 23, 2004 -- Women with a genetic mutation that makes them especially vulnerable to getting breast cancer can now quantify the benefit of an extreme, but often advised, option to lower their risk: Having both breasts surgically removed before there are any signs of cancer.

Double mastectomy lowers breast cancer risk by 90% in women with the so-called breast cancer genes, according to new research. In the six-year study, only two of 108 women with BRCA1 or BRCA2 mutations developed breast cancer after having the preventive surgery, compared to half of 378 others who didn't.

Mastectomy, the surgical removal of all breast tissue, is more typically done after cancer has been diagnosed. But women with inherited mutations of either BRCA gene are often advised to have this and another surgery as preventive measures because they face up to an 80% chance of developing breast cancer in their life, and have at least a 10%-20 % chance of getting ovarian cancer.

"Our study should in no way be interpreted as us saying 'go out and have this surgery' because this is a very personal decision for these women. But the surgeries do reduce risk," researcher Timothy R. Rebbeck, PhD, of the University of Pennsylvania School of Medicine, tells WebMD.

"With our findings, we hope that women and their doctors now have more information to make a better decision about managing their risk with mastectomy. A lot of women with this genetic mutation are advised to get surgery as a means to reduce their cancer risk, but up until now, there has been no firm data on the magnitude of the risk reduction from this surgery."

In addition to preventive mastectomy, women with BRCA mutations -- typically those of Eastern European (or Ashkenazi) Jewish descent and with a strong family history of breast or ovarian cancer before menopause -- are often advised to undergo prophylactic oophorectomy, the surgical removal of cancer-free ovaries as a preventive measure.

The ovaries produce many hormones, including estrogen and progesterone, which have been linked to breast cancer.

Previously, research led by Rebbeck, program leader of Penn's Cancer Epidemiology and Risk Reduction Program, showed that removal of the ovaries could reduce ovarian cancer risk by some 90% in BRCA women, and lowered their later risk of breast cancer by 50% to 70%. A blood test can determine if you have a BRCA mutation, which is also responsible for many of the rare cases of breast cancer in men.