Risk is also higher when relatives have been affected with CRC at a young age, particularly if cancer has occurred before age 50. Most people with a family history of CRC have only one affected relative. Both of these conditions are rare, but people with these conditions require special approaches to early detection and treatment to reduce their cancer risk. When a family history indicates the possibility of a high-risk family, further investigation is merited to determine whether these conditions are present. Specific family history characteristics that suggest an inherited cancer syndrome include colorectal cancer in succeeding generations, onset of cancer before age 50, and the presence of other cancers associated with an inherited risk of colorectal cancer, especially endometrial cancer.
Suspicion increases with an increasing number of affected family members.
Using family history to make screening decisions CRC screening is recommended for all Americans starting at age 50. Although early detection strategies are limited for these cancers, some experts recommend the use of screening measures such as serum CA-125 levels, pelvic ultrasound and urine cytology when these cancers are present in the family. Family history evaluation is thus a two-step process. In the first step, the presence or absence of a family history of colorectal cancer is determined. If a positive history of CRC is found, the second step determines whether the family history indicates a possible high-risk family.