Understanding the contribution of family history to colorectal cancer risk and its clinical implications: A state‐of‐the‐science review

Abstract

Background Persons with a family history (FH) of colorectal cancer (CRC) or adenomas that are not due to known hereditary syndromes have increased risk for CRC. Understanding these risks, screening recommendations and screening behaviors can inform strategies to reduce CRC burden in these families. Methods A comprehensive review of literature published within the past 10 years was conducted to assess what is known about cancer risk, screening guidelines, adherence and barriers to screening and effective interventions in persons with FH of CRC, and to identify FH tools used to identify these individuals and inform care. Results Existing data show that having one affected first-degree relative (FDR) increases CRC risk by 2-fold, and risk increases with multiple affected FDRs and younger age at diagnosis. There was variability in screening recommendations across consensus guidelines. Screening adherence was <50% and lower in persons under age 50. Having a provider’s recommendation, multiple affected relatives and family encouragement facilitated screening; insufficient collection of FH, low knowledge of guidelines, and poor family communication were important barriers. Effective interventions incorporated strategies for overcoming barriers but these have not been tested broadly in clinical settings. Conclusions Four strategies for reducing CRC in persons with familial risk are suggested: 1) improve how we collect and utilize cancer FH, 2) establish consensus for screening guidelines by FH, 3) enhance provider-patient knowledge of guidelines and communication about CRC risk, 4) encourage survivors to promote screening within their families, and partner with existing screening programs to expand reach to high-risk groups.

Advanced-Stage Colorectal Cancer in Persons Younger Than 50 Years Not Associated With Longer Duration of Symptoms or Time to Diagnosis

“…31 The Family History Task Group of the National Colon Cancer Roundtable (NCCRT) has recently recommended strategies for persons with familial risk, including improving the collection and utilization of family history. 32 Additional strategies will be needed to address the problem of young-onset CRC in those without a family history of CRC, recognized cancer genetic syndromes, or inflammatory bowel disease.…”

Colorectal Cancer Screening: Recommendations for Physicians and Patients from the U.S. Multi-Society Task Force on Colorectal Cancer

“…Persons in families with syndrome X should undergo colonoscopy at least every 3 to 5 years, beginning 10 years before the age at diagnosis of the youngest aff ected relative. A family history of CRC in a fi rst-degree relative increases the risk of CRC regardless of the age at diagnosis of the aff ected relative (123)(124)(125). Th ere is a gradient of risk such that the younger the age of the aff ected relative, the greater the risk (123)(124)(125).…”

“…Th e greatest relative risk of CRC appears to be in persons <50 years who have a fi rst-degree relative with CRC diagnosed at <50 years (123)(124)(125). Compliance in young persons with a family history of CRC is suboptimal, and clinicians should make special eff orts to ensure that screening occurs.…”

“…A family history of CRC in a fi rst-degree relative increases the risk of CRC regardless of the age at diagnosis of the aff ected relative (123)(124)(125). Th ere is a gradient of risk such that the younger the age of the aff ected relative, the greater the risk (123)(124)(125). Th e MSTF has previously used age 60 as a threshold of risk elevation, so that a single fi rst-degree relative diagnosed with CRC at age <60 years warrants both earlier screening and at morefrequent intervals ( 1 ).…”

Establishing a valid approach for estimating familial risk of cancer explained by common genetic variants

“…We will use colorectal cancer (CRC), the third most common cancer globally, whose heritability was estimated to be 35%, as an example to demonstrate our approach. Next to others, FH has been identified as a major CRC risk factor . In the past decade, more and more SNPs associated with CRC risk have been discovered by GWAS (e.g …”