A Family Affair: The Genetics of Stomach Cancer
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Karen Chelcun Schreiber can't imagine knowing she is genetically susceptible to a deadly type of gastric cancer and not doing something to lower her risk.
"To me, knowing and doing are one and the same when you're talking about your family's life and health," she says.
Her family member's lives took an abrupt turn in 2007 after her oldest brother was diagnosed with stage IV diffuse type gastric cancer, the same cancer that had claimed their mother's life. Greg's fight became everyone's battle with the discovery of a genetic trait that raises the family's lifetime risk for diffuse gastric cancer to greater than 80 percent and also boosts lifetime risks for lobular breast cancer and colon cancers.
Guidance from Amy Stettner, a senior genetics counselor at the UW Carbone Comprehensive Cancer Center, helped many of the family members grasp the implications of this sudden revelation, review their options and make decisions, Schreiber says. Although Greg died in February 2009, he saw several family members take action that stopped cancers that hadn't even been detected.
Detection is an ongoing challenge with gastric cancer. As with Schreiber's relatives, people tend to be asymptomatic until it reaches an advanced stage. Eighty to 90 percent of newly diagnosed patients present with metastatic disease, according to the National Cancer Institute, a tendency that is reflected in NCI's latest 5-year survival rate for stage IV stomach cancer: 4 percent. Gastric cancer is among the world's most-diagnosed cancers, according to the World Health Organization, with a death rate second only to lung cancer.
"One day she was fine, the next day she had cancer - and all too soon she was gone," says Schreiber.
Greg was diagnosed at 56. Upon hearing that chemotherapy would slow his cancer, not cure it, she wondered, "What's changed in the last 25 years?"
"One answer: medical genetics," says Stettner.
First, tests after Greg's surgery revealed diffuse gastric cancer, the cancer type associated with a genetic cancer susceptibility syndrome called hereditary diffuse gastric cancer (HDGC), which confers elevated risks for gastric, lobular breast and colon cancer. Genetic testing performed from a blood sample then confirmed Greg had a mutation in the E-cadherin (CDH1) gene, a genetic trait in about 100 families worldwide, Stettner says.
Schreiber had learned about HDGC and CDH1 while researching treatment options for her brother and even urged him to have genetic testing.
"When I read about this hereditary thing, I kept telling myself, 'It can't be us, it can't be us. It's too rare.' And all the time I'm thinking, 'I don't want it to be us!' But my intuition was telling me it was us," Schreiber says.
Schreiber contacted Stettner and they reviewed the family pedigree and cancer history (two known gastric cancers). Stettner later met with six family members as a group, helping them understand the implications of the genetic trait and review alternatives.
Eight family members have had genetic testing; six have the CDH1 gene mutation, Stettner says. A handful of laboratories perform the tests from blood samples, with results returned in about six weeks.
Two adult family members chose not to be tested, Schreiber says, and minor children will be referred to Stettner or a colleague at age 18 so they, too, can make informed decisions.
Four family members with the gene mutation have since had prophylactic total gastrectomy - in effect, had their stomachs surgically removed to eliminate gastric cancer risk. That action is strongly recommended for anyone with the CDH1 mutation, along with increased screening for the other cancers associated with the syndrome.
Life without a stomach demands new eating habits and a careful diet, says Schreiber, who had the surgery in September 2008.
"It was scary, but I did my research. I really wanted my quality-of-life to be the same after the surgery. And it is."
Her youngest brother and Greg's two children took the same precautionary step, with prompt payoff.
After all four procedures, diffuse gastric carcinoma was discovered in excised tissue, with the most aggressive cancers found in Greg's children, both age 26 at the time of surgery, Schreiber says. None of those cancers had been detected through standard screening, at-risk surveillance or symptoms, she says.
Meanwhile, Schreiber has gone from self-described "family poster child for action" to founder and president of a non-profit advocacy group for stomach cancer research, "No Stomach for Cancer." Its board of directors has international representation, including the New Zealand geneticist who first identified the CDH1 mutation in 1998. She met him and toured his lab in February 2011.
Schreiber recently made this observation on the group's website: "I wonder what will change by next year... One thing I know: we will not have to suffer the loss of another loved one in our family to HDGC."
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