Colorectal cancer (CRC) is the fourth most common cancer amongst men and women. Between 3 and 6% of all CRCs are attributed to well-defined inherited syndromes, including Lynch syndrome, familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), and several hamartomatous polyposis conditions. Identification of these patients through family history and appropriate genetic testing can provide estimates of cancer risk that inform appropriate cancer screening, surveillance and/or preventative interventions. This narrative review examines the hereditary colorectal cancer and polyposis syndromes, their genetic basis, clinical management, and evidence supporting cancer screening.

Genetic testing of minors is advised only for conditions in which benefits of early intervention outweigh potential psychological harms. This study investigated whether genetic counseling and test reporting for the CDKN2A/p16 mutation, which confers highly elevated melanoma risk, improved sun protection without inducing distress. Eighteen minors (M = 12.4, SD = 1.9) from melanoma-prone families completed measures of protective behavior and distress at baseline, 1 week (distress only), 1 month, and 1 year following test disclosure. Participants and their mothers were individually interviewed on the psychological and behavioral impact of genetic testing 1 month and 1 year post-disclosure. Carriers (n = 9) and noncarriers (n = 9) reported significantly fewer sunburns and a greater proportion reported sun protection adherence between baseline and 1 year post-disclosure; results did not vary by mutation status. Anxiety symptoms remained low post-disclosure, while depressive symptoms and cancer worry decreased. Child and parent interviews corroborated these findings. Mothers indicated that genetic testing was beneficial (100%) because it promoted risk awareness (90.9%) and sun protection (81.8%) without making their children scared (89.9%); several noted their child's greater independent practice of sun protection (45.4%). In this small initial study, minors undergoing CDKN2A/p16 genetic testing reported behavioral improvements and consistently low distress, suggesting such testing may be safely implemented early in life, allowing greater opportunity for risk-reducing lifestyle changes.

A CDKN2A/p16 mutation confers 28%-67% lifetime melanoma risk, a risk that may be moderated by ultraviolet radiation exposure. The aim of this study was to test whether melanoma genetic counseling and test disclosure conferred unique informational, motivational, or emotional benefits compared to family history-based counseling. Participants included were 114 unaffected members of melanoma-prone families, ages 16-69, 51.8% men, 65.8% with minor children or grandchildren. Carriers (n = 28) and noncarriers (n = 41) from families with a CDKN2A mutation were compared to no-test controls (n = 45) from melanoma-prone families without an identifiable CDKN2A mutation. All participants received equivalent counseling about melanoma risk and management; only CDKN2A participants received genetic test results. Using newly developed inventories, participants rated perceived costs and benefits for managing their own and their children's or grandchildren's melanoma risk 1 month and 1 year after counseling. Propensity scores controlled for baseline family differences. Compared to no-test controls, participants who received test results (carriers and noncarriers) reported feeling significantly more informed and prepared to manage their risk, and carriers reported greater motivation to reduce sun exposure. All groups reported low negative emotions about melanoma risk. Parents reported high levels of preparedness to manage children's risk regardless of group. Carrier parents reported greater (but moderate) worry about their children's risk than no-test control parents. Women, older, and more educated respondents reported greater informational and motivational benefits regardless of group. Genetic test results were perceived as more informative and motivating for personal sun protection efforts than equivalent counseling based on family history alone.

Cowden syndrome (CS) is an often difficult to recognize hereditary cancer predisposition syndrome caused by mutations in phosphatase and tensin homolog deleted on chromosome 10 (PTEN). In addition to conferring increased cancer risks, CS also predisposes individuals to developing hamartomatous growths in many areas of the body. Due to the rarity of CS, estimates vary on the penetrance of certain phenotypic features, such as macrocephaly and skin findings (trichilemmomas, mucocutaneous papules), as well as the conferred lifetime cancer risks. To address this variability, separate clinical diagnostic criteria and PTEN testing guidelines have been created to assist clinicians in the diagnosis of CS. As knowledge of CS increases, making larger studies of affected patients possible, these criteria continue to be refined. Similarly, the management guidelines for cancer screening and risk reduction in patients with CS continue to be updated. This review will summarize the current literature on CS to assist clinicians in staying abreast of recent advances in CS knowledge, diagnostic approaches, and management.