Abstract
It is estimated that 5 to 10% of all colorectal cancer (CRC) cases are attributed
to a hereditary cause. The primary hereditary cancer syndromes that confer an increased
risk for colorectal cancers are Lynch syndrome/hereditary nonpolyposis colorectal
cancer (HNPCC) and familial adenomatous polyposis (FAP). Through genetic testing,
health care providers can identify patients and families who carry gene mutations
and subsequently are at a substantially greater risk for developing colorectal cancer
than the general population. Genetic testing provides risk information not only about
an individual patient, but also his or her biological relatives. A variety of risk-reduction
behaviors (including screening, surgery, and health and lifestyle behaviors) have
been examined in Lynch syndrome and FAP populations. The research indicates that screening
behaviors are less than optimal, although the rates vary from study to study. Prophylactic
colectomy is the primary course of treatment for individuals who test positive for
a FAP mutation, but the results are inconclusive for cancer-unaffected Lynch syndrome
mutation carriers. Although research suggests that the adoption of healthy lifestyles
and behaviors (e.g., diet, physical activity, weight control, smoking cessation, limited
alcohol consumption) could have a favorable impact on colon cancer burden, there is
minimal data on how these behaviors may moderate cancer risk among those at risk of
hereditary colon cancer. To date, we know very little about the actual health and
lifestyle behaviors of those at risk of hereditary colon cancer. Genetic testing and
counseling at risk individuals may resolve uncertainty about their personal and familial
cancer risk and provide information to guide and personalize decisions about their
future health care.
Keywords
hereditary nonpolyposis colorectal cancer (HNPCC) - Lynch syndrome - familial adenomatous
polyposis (FAP) - genetic counseling and testing - decision making
