Family History of Cancer May Raise This Risk, Too
Large European study looked at people with close relatives who'd been affected
"A major strength of our study is that we were able to adjust our analyses for tobacco, alcohol and a number of other lifestyle habits, which most previous studies have not been able to do," Negri said.
The study's reliance on survey data, however, is a significant weakness that may have caused the authors to overstate the odds of cancer risk, said Mia Gaudet, director of genetic epidemiology for the American Cancer Society.
"At the time the cases are reporting family history, they already know they have cancer," Gaudet said. "It's an emotional time, and they are more likely to recall family members who have had cancer."
By the same token, the comparison patients without cancer may be less likely to recall family instances of cancer because they don't have the same motivation. "This can really introduce differences in how individuals recall any particular exposures, and this difference could be particularly profound when it comes to cancer," Gaudet said.
Follow-up genetic research into the potential associations between different types of cancer reported by the European researchers is warranted , she said.
In addition, people with a family history of cancer might want to discuss with their physician whether they should see a genetic counselor to assess their cancer risk, Gaudet said.
This emphasis on genetics, however, should not discourage people with a family history of cancer, both Kraus and Gaudet said.
"We can't control where we get our genes, but what you can control is your risk factors," Kraus said, noting that healthy diet, an active lifestyle and avoiding drinking or smoking can play just as important a role as genetics in determining a person's cancer risk.
Although the study found a link between higher risk for different types of cancer in people whose close family members had cancer, it did not establish a cause-and-effect relationship.