THURSDAY, July 25 (HealthDay News) -- A family history of cancer
raises your overall risk of developing cancer, including types of
cancer far removed from those suffered by your relatives, according
to a new study of 23,000 people.
Doctors have long known that people have an increased risk of
developing the same type of cancer as a close relative. In
addition, some genetics studies have found that common gene
mutations can increase the risk of different types of cancer -- for
example, one genetic abnormality can increase risk of both breast
and ovarian cancer in women.
But this review, performed by European researchers and published
July 25 in the journal
Annals of Oncology, found that a close family member's
history of cancer appears to increase a person's risk of suffering
either the same cancer or a different type of cancer.
"It looks like there clearly are associations between family members developing cancer and you developing cancer," said Dr. Dennis Kraus, director of the Center for Head and Neck Oncology at the New York Head & Neck Institute at Lenox Hill Hospital in New York City. He was not involved with the new research.
"It's a well-done study," Kraus said. "It's a huge number of patients where they had controls, and they were able to take into account lifestyle and try to remove things like smoking and drinking from the equation."
Significant associations found in the study include:
First-degree relatives are parents, brothers, sisters, sons and
"Our results point to several potential cancer syndromes that appear among close relatives and that indicate the presence of genetic factors influencing multiple cancer sites," said study co-author Dr. Eva Negri.
"These findings may help researchers and clinicians to focus on the identification of additional genetic causes of selected cancers and on optimizing screening and diagnosis, particularly in people with a family history of cancer at a young age," said Negri, head of the laboratory of epidemiologic methods at the Mario Negri Institute for Pharmacological Research in Milan, Italy.
The researchers from Italy, Switzerland and France looked at
12,000 cases of cancer occurring in 13 different parts of the body
between 1991 and 2009, and matched them to control cases of 11,000
people without cancer. For both groups they collected information
on any cancer in the family, as well as data on health and
lifestyle factors that can influence a person's cancer risk.
"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,"
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.
To learn more about genetics and cancer, visit the
American Cancer Society.
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