Offspring more susceptible if parents had tumors

You can't inherit cancer from your mother or father, but if a parent had cancer -- especially certain kinds -- you want to be extra vigilant about screening for the disease, experts say.

All cancers are said to be genetic in origin, in that they stem from DNA mutations that cause out-of-control cell growth.

But that's not the same as being inherited. The genetic propensity for cancer won't in itself give you cancer.

Cancer experts believe that up to 10 percent of cancers are caused by single genes that go awry and get transmitted across generations. These "susceptibility genes" put a person at a much greater risk of developing cancer in specific organs.

The tumor could be triggered by a variety of environmental conditions -- including cigarette smoke, chemicals or simply time.

The most well-known inherited tumors are linked to mutations in two genes and affect the breasts and ovaries. These gene flaws raise the lifetime risk of breast cancer to as high as 87 percent, compared with an 11 percent risk in the general population. They raise the risk of ovarian cancer to 44 percent, compared with the regular risk of about 2 percent.

The same two genes also have been associated with inherited forms of colorectal cancer and prostate cancer in men. Inheritance is implicated in a rare form of colon tumor called hereditary nonpolyposis colorectal cancer, and researchers also have identified susceptibility genes for thyroid cancer and skin cancer.

A study by researchers in Germany and Sweden found that children whose parents had cancer were much more likely than their peers to develop the same illness, and the family connection was very strong for certain tumors.

Men had a 15 percent chance of getting prostate cancer, anyone with a parent who'd had intestinal cancer had a 10 percent risk of the same ailment, and women had an 8.5 percent risk of breast cancer if their mother had it.

Sons of fathers with testicular cancer had four times the risk of developing the disease, compared with sons whose fathers did not have it. Brothers of affected men were nine times more likely to develop it, too.

But cancer experts stress that this does not mean that people with increased risk definitely will develop cancer.

"If we have a mutation, it poses a greater risk or liability [of illness] but not a certainty," Carolyn Farrell, director of the clinical genetics service at the Roswell Park Cancer Institute in Buffalo, N.Y., told HealthDay .

Genetic counselors advise people with a strong family history of cancer to be vigilant about screening for the disease, with tests such as breast mammography or colon imaging.