For others, such as Stacey Jacobson of Lower Gwynedd, breast cancer was virtually unknown in their families. Perhaps the high-risk gene had sneaked down their paternal line, or maybe their grandmother had been misdiagnosed with some other type of cancer.
From 5 percent to 10 percent of breast cancers are thought to be due to an inherited genetic mutation in BRCA1 or BRCA2, the so-called breast-cancer genes, which also raise the risk of ovarian cancer. In the general population, scientists estimate, one in every 300 to 500 people carries a BRCA mutation. In Ashkenazi Jews, those of Eastern European descent, the prevalence climbs to one in 40.
Other ethnic and geographic groups around the world, such as the people of Norway, the Netherlands, and Iceland, more often carry specific BRCA1 and BRCA2 mutations, according to the National Cancer Institute.
A study of Northern California breast-cancer patients younger than 65 compared the frequency of BRCA1 mutations in U.S. ethnic and racial groups. As expected, Ashkenazi patients were most likely to carry a BRCA1 mutation. But Hispanic patients topped the other groups, which researchers said might be due to unrecognized Jewish ancestry.
Women without a BRCA mutation or a strong family history of breast cancer have a 13 percent lifetime risk of developing the disease. Women with a mutation in either BRCA gene have an estimated lifetime breast-cancer risk of 50 percent to 85 percent, and research suggests Ashkenazi women fall on the higher end of that spectrum.
Ever since she was a little girl, Cohen, now 43, figured she was destined to develop breast cancer.
On her first date with the man she would marry, Cohen said, "I brought up breast cancer and how that could be in the future."
Her mother was around 10 when she lost her own mother, only 38, to the disease.
"I feel like I grew up with it because my mom always spoke about her mother," Cohen said. "She idolized her. She was afraid it was going to happen to her."
Cohen's mother was prescient. She died nearly 20 years ago at 54 of breast cancer.
Cohen decided to pursue genetic testing when she was 35, only a few years younger than the age at which her grandmother died. "I felt like my clock was ticking.
"I became obsessed with this, and I needed to know."
Deep down she held out hope that she had somehow won the BRCA coin toss, that she had inherited her mother's normal copies of the genes, not a copy that would increase her cancer risk several-fold.
An acquaintance who had gone through counseling and testing herself suggested that Cohen first see if she could obtain a section of her mother's tissue for testing. Only a minority of women with a strong family history of breast cancer carry a BRCA mutation; other, as-yet-unidentified genes could play a role in the others. If her mother had a BRCA mutation, there was a 50-50 chance Cohen had inherited it.
"I look at it like she left me a gift," Cohen said of that bit of her mother's tissue. Testing at the Fox Chase Cancer Center revealed that her mother indeed had a BRCA mutation, setting the stage for Cohen to be tested.
When she learned that she carried the same mutation, "I was so devastated. . . It was almost like I was grieving for my mom all over again."
Unlike Cohen, Jacobson, 40, never really thought much about breast cancer. Her mother, 66, has never had it. But her mother does have an unrelated and unusual skin cancer, which prompted her dermatologist to refer her to a genetics counselor.
The counselor became suspicious when Jacobson's mother mentioned that there was breast and ovarian cancer in women on her father's side and suggested she be tested for the Ashkenazi BRCA mutations.
Doctors used to tell women not to worry if breast cancer ran on their father's side, Jacobson said. No more.
"We went from pretty much thinking we had no family history to realizing we were surrounded by it," Jacobson said. Turns out her maternal grandfather's sister and his mother and her two sisters, Jacobson's great-grandmother and great-great-aunts, all had breast cancer. And two of her maternal grandfather's relatives had ovarian cancer.
Her mother learned last November that she did have a BRCA mutation, while testing a few months later revealed that Jacobson did, too. "I was actually calm about it at the time," Jacobson recalled. "I hadn't watched a mother or a grandmother with these diseases."
That is why some people who have inherited a mutation from their father's side do not know they are at risk, said Sue Friedman, 48, founder and executive director of Facing Our Risk of Cancer Empowered, or FORCE, which promotes genetic counseling for women whose family history suggests they have a BRCA mutation (FORCE coined the term "previvor" more than a decade ago).
About 60 percent to 70 percent of women with a BRCA mutation eventually have their ovaries removed, said Timothy Rebbeck, a University of Pennsylvania epidemiologist. Rebbeck heads up the world's largest prospective study of women with BRCA mutations, with over 5,000 women enrolled at research centers worldwide.
"Probably every woman [with a BRCA mutation] should have an oophorectomy at some point," Rebbeck said. "It's lifesaving." Some women put the surgery off because they want more children, others because they "are in denial," he said. "They're not dealing with the information they have. They're choosing by not choosing."
Removing the ovaries cuts the risk of ovarian cancer by 80 percent to 90 percent in women with a BRCA mutation, he said. And, because the ovaries produce hormones that feed breast tumors, an oophorectomy also reduces their risk of breast cancer by half.
Far fewer women opt for a preventive mastectomy, Rebbeck said, although the rate varies. In the Netherlands, he said, most women with BRCA mutations choose to have a mastectomy; in Spain, almost none. The U.S. falls between the two, he said.
For Cohen, v.p. for FORCE's volunteer programs, and Jacobson, active with the group's Philadelphia chapter, preventive surgery was a no-brainer. Their families were complete, and they did not want to live with the specter of cancer and frequent breast biopsies. Each had a double mastectomy and reconstructive surgery as well as an oophorectomy.
Jacobson knows many women her age who did not find out until after they were diagnosed with cancer that they had a BRCA mutation. With her preventive surgery behind her, Jacobson said, "I truly, truly feel like I've been given a life sentence. It's not a death sentence. It's a life sentence."
FORCE's Philly chapter is at: www.facingourrisk.org/philadelphia
Contact Rita Rubin at firstname.lastname@example.org.