Managing young colorectal cancer: a UK and Irish perspective

Familial Colorectal Cancer Type X

The genetic background is unknown for the 50-60% of the HNPCC families, who fulfill the Amsterdam criteria, but do not have a mutation in an MMR gene, and is referred to as FCCTX. This study reviews the clinical, morphological and molecular characteristics of FCCTX, and discusses the molecular genetic methods used to localize new FCCTX genes, along with an overview of the genes and chromosomal areas that possibly relate to FCCTX. FCCTX is a heterogeneous group, mainly comprising cases caused by single high-penetrance genes, or by multiple low-penetrance genes acting together, and sporadic CRC cases. FCCTX differs in clinical, morphological and molecular genetic characteristics compared to LS, including a later age of onset, distal location of tumours in the colon, lower risk of developing extracolonic tumours and a higher adenoma/carcinoma ratio, which indicates a slower progression to CRC. Certain characteristics are shared with sporadic CRC, e.g. similarities in gene expression and a high degree of CIN+, with significanly increased 20q gain in FCCTX. Other molecular characteristics of FCCTX include longer telomere length and hypomethylation of LINE-1, both being a possible explanation for CIN+. Some genes in FCCTX families (RPS20, BMPR1A, SEMA4A) have been identified by using a combination of linkage analysis and sequencing. Sequencing strategies and subsequent bioinformatics are improving fast. Exome sequencing and whole genome sequencing are currently the most promising tools. Finally, the involvement of CNV’s and regulatory sequences are widely unexplored and would be interesting for further investigation in FCCTX.

Risk of metachronous colorectal cancer following colectomy in Lynch syndrome: a systematic review and meta-analysis

AIM

Lynch syndrome (LS) accounts for 2-4% of all colorectal cancer (CRC) cases, and is associated with an increased risk of developing metachronous colorectal cancer (mCRC). The role of extended colectomy in LS CRC is controversial. There are limited studies comparing the risk of mCRC following segmental colectomy and extended colectomy. The objective of this systematic review is to evaluate the risk of developing mCRC following segmental and extended colectomy for LS CRC and endoscopic compliance.

METHOD

A systematic review of major databases was performed using predefined terms. All original articles published in English comparing the risk of mCRC in LS patients after segmental and extended colectomy from 1950 to January 2016 were included.

RESULTS

The search retrieved 324 studies. Six studies involving 871 patients met the inclusion criteria. Of these, 705 (80.9%) underwent segmental colectomy and 166 (19.1%) extended colectomy. Average follow-up was 91.2 months. The mCRC rate was 22.8% and 6% in the segmental and extended colectomy groups, respectively. The segmental group were over four times more likely to develop mCRC (OR 4.02, 95% CI: 2.01-8.04, P < 0.0001). mCRC occurred in patients after segmental colectomy despite 1-2-yearly postoperative endoscopic surveillance.

CONCLUSION

This result suggests that extended colectomy reduces the risk of mCRC by over four-fold compared with segmental colectomy. mCRC occurred in the segmental group despite postoperative endoscopic surveillance. This needs to be borne in mind when deciding on the appropriate surgical management of LS patients with CRC. We recommend that extended colectomy should be considered for patients with confirmed LS CRC.

The evolution of colorectal cancer genetics-Part 2: clinical implications and applications

The genetic understanding of colorectal cancer (CRC) continues to grow, and it is now estimated that 10% of the population has a known hereditary CRC syndrome. This article will examine the evolving surgical and medical management of hereditary CRC syndromes, and the impact of tumor genetics on therapy. This review will focus on the most common hereditary CRC-prone diseases seen in clinical practice, which include Lynch syndrome (LS), familial adenomatous polyposis (FAP) & attenuated FAP (AFAP), MutYH-associated polyposis (MAP), and serrated polyposis syndrome (SPS). Each section will review the current recommendations in the evaluation and treatment of these syndromes, as well as review surgical management and operative planning. A highly detailed multigeneration cancer family history with verified genealogy and pathology documentation whenever possible, coupled with germline mutation testing when indicated, is critically important to management decisions. Although caring for patients with these syndromes remains complex, the application of this knowledge facilitates better treatment of both individuals and their affected family members for generations to come.