Mapping psychosocial interventions in familial colorectal cancer: a rapid systematic review

Background Approximately 5% of colorectal cancer (CRC) cases are part of a well-defined inherited genetic syndrome and up to approximately 30% of these cases have a clinically defined familial basis. Psychosocial interventions in familial colorectal cancer address aspects mainly focused on affective, cognitive and behavioural outcomes. The present review aims to systematically map out the available psychosocial interventions for individuals with a family history of CRC and describe the current state of the research. Methods An extensive electronic search was conducted to investigate the literature published until June 2020. Inclusion criteria consisted of quantitative studies published in English that explored the impact of psychosocial interventions for familial CRC, clearly defined the psychosocial intervention offered and included participants with a family history of CRC. Results The analysis included 52 articles. Genetic counselling, educational interventions, psychological interventions and multimodal interventions were identified across the studies. In terms of diagnoses, Lynch Syndrome, Familial Adenomatous Polyposis, Familial Colorectal Cancer were the main conditions included in the studies. Affective, cognitive, behavioural aspects and quality of life emerged as the most frequently explored outcomes. The studies included individuals with both personal and familial history of CRC or family history alone. Conclusions Our rapid review provides an overview of the literature exploring the impact of psychosocial interventions for familial CRC. The psychosocial interventions identified had an overwhelmingly positive impact across all types of outcomes measured. Genetic counselling appeared to be most beneficial, and this is expected as it is purposively designed to address genetic conditions. Further quantitative analysis of primary empirical research is needed to determine the efficacy and effectiveness of psychosocial interventions as well as the mechanisms through which they exert their effect.

Germline Variants of CYBA and TRPM4 Predispose to Familial Colorectal Cancer

Familial colorectal cancer (CRC) is only partially explained by known germline predisposing genes. We performed whole genome sequencing in 15 Polish families of many affected individuals, without mutations in known CRC predisposing genes. We focused on loss-of-function variants and functionally characterized them. We identified a frameshift variant in the CYBA gene (c.246delC) in one family and a splice site variant in the TRPM4 gene (c.25-1 G>T) in another family. While both variants were absent or extremely rare in gene variant databases, we identified four additional Polish familial CRC cases and two healthy elderly individuals with the CYBA variant (odds ratio 2.46, 95% confidence interval 0.48-12.69). Both variants led to a premature stop codon and to a truncated protein. Functional characterization of the variants showed that knockdown of CYBA or TRPM4 depressed generation of reactive oxygen species (ROS) in LS174T and HT-29 cell lines. Knockdown of TRPM4 resulted in decreased MUC2 protein production. CYBA encodes a component in the NADPH oxidase system which generates ROS and controls, e.g., bacterial colonization in the gut. Germline CYBA variants are associated with early onset inflammatory bowel disease, supported with experimental evidence on loss of intestinal mucus barrier function due to ROS deficiency. TRPM4 encodes a calcium-activated ion channel, which in a human colonic cancer cell line controls calcium-mediated secretion of MUC2, a major component of intestinal mucus barrier. We suggest that the gene defects in CYBA and TRPM4 mechanistically involve intestinal barrier integrity through ROS and mucus biology, which converges in chronic bowel inflammation.

Familial bowel cancer

Health Education England recognises the increasing relevance of genomics in medicine, and therefore, the importance for all specialists of applying knowledge and understanding of genomics to their work. This article looks specifically at familial colorectal cancer and the role of primary care clinicians in diagnosis and management.

Whole Exome Sequencing Identifies APCDD1 and HDAC5 Genes as Potentially Cancer Predisposing in Familial Colorectal Cancer

Germline mutations in predisposition genes account for only 20% of all familial colorectal cancer (CRC) and the remaining genetic burden may be due to rare high-to-moderate-penetrance germline variants that are not explored. With the aim of identifying such potential cancer predisposing variants, we performed whole exome sequencing on three CRC cases and three unaffected members of a Polish family and identified two novel heterozygous variants; a coding variant in APC down-regulated 1 gene (APCDD1, p.R299H) and a non-coding variant in the 5’ untranslated region (UTR) of histone deacetylase 5 gene (HDAC5). Sanger sequencing confirmed the variants segregating with the disease and Taqman assays revealed 8 additional APCDD1 variants in a cohort of 1705 familial CRC patients and no further HDAC5 variants. Proliferation assays indicated an insignificant proliferative impact for the APCDD1 variant. Luciferase reporter assays using the HDAC5 variant resulted in an enhanced promoter activity. Targeting of transcription factor binding sites of SNAI-2 and TCF4 interrupted by HDAC5 variant showed a significant impact of TCF4 on promoter activity of mutated HDAC5. Our findings contribute not only to the identification of unrecognized genetic causes of familial CRC but also underline the importance of 5´UTR variants affecting transcriptional regulation and the pathogenesis of complex disorders.