Do you know your family's precise cancer history? Depending on your age, you may believe that that information is irrelevant until later in life — but a multi-institutional report published in the latest issue of the Journal of the American Medical Association and released Tuesday suggests that familial cancer history is most significant in early adulthood.

For 11 years, Baylor College of Medicine has been involved with the Cancer Genetics Network database, a group of statisticians, clinicians and oncologists, which has registered data on family cancer history of more than 10,000 patients.

"What we realized is that there was not a study on how family cancer history changes over a lifetime," says Dr. Sharon Plon, the senior author of the report, director of Baylor College of Medicine Cancer Genetics Clinic and professor of pediatrics and molecular and human genetics at BCM.

"We wanted to look at family history changes that would make a physician make different recommendations," she tells CultureMap.

To conduct the study, Plon's team reconstructed family cancer history from the day subjects were born, examining every year until they entered the study. "The major result of the study is the fact that if you take a good family history at the age of 30, you'll pick up the individuals with high risk for breast, colon and prostate cancer."

The report examined incidences of breast, colon and prostate cancers in first and second-degree history — parents, siblings, grandparents and aunts and uncles. Explains Plon, "For colon cancer, there were only about two to three percent of individuals at the age of 30 with family history that would put them in that higher risk category. There were another five percent that became high risk later on.

"What this allowed us to say is that it's important for physicians to get a family history of cancer when they see a young adult patient, and update it so they don't miss changes that require, say, early colonoscopy or intensive breast screening."

When providing doctors with familial cancer history, it's critical to list at what age a family member was diagnosed with cancer and where. That information should be updated every five to 10 years until at least age 50, Plon says.

She notes that increasing use of electronic health records will make the report's suggestions easier to implement. As more familial cancer history changes are logged between the ages of 30 and 50, the rate of early detection will improve, which is not only more cost effective, but can prevent advanced-stage cancer and, ultimately, save lives.