Screening for Lynch syndrome in young Saudi colorectal cancer patients using microsatellite instability testing and next generation sequencing

The Genomic Landscape of Colorectal Cancer in the Saudi Arabian Population Using a Comprehensive Genomic Panel

PURPOSE

Next-generation sequencing (NGS) technology detects specific mutations that can provide treatment opportunities for colorectal cancer (CRC) patients.

PATIENTS AND METHODS

We analyzed the mutation frequencies of common actionable genes and their association with clinicopathological characteristics and oncologic outcomes using targeted NGS in 107 Saudi Arabian patients without a family history of CRC.

RESULTS

Approximately 98% of patients had genetic alterations. Frequent mutations were observed in BRCA2 (79%), CHEK1 (78%), ATM (76%), PMS2 (76%), ATR (74%), and MYCL (73%). The APC gene was not included in the panel. Statistical analysis using the Cox proportional hazards model revealed an unusual positive association between poorly differentiated tumors and survival rates (p = 0.025). Although no significant univariate associations between specific mutations or overall mutation rate and overall survival were found, our preliminary analysis of the molecular markers for CRC in a predominantly Arab population can provide insights into the molecular pathways that play a significant role in the underlying disease progression.

CONCLUSIONS

These results may help optimize personalized therapy when drugs specific to a patient's mutation profile have already been developed.

Prevalence and Genotype-Phenotype Correlation of Lynch Syndrome in a Selected High-Risk Cohort from Qatar’s Population

Lynch syndrome (LS) is the most common cause of hereditary colorectal cancers (CRC) and is associated with an increased risk for ovarian and endometrial cancers. There is lack of knowledge on the epidemiology of LS in the non-Caucasian populations especially in Qatar. The aim of this retrospective study is to explore the prevalence of LS in a selected high-risk cohort in the State of Qatar in addition to investigating the frequency and genotype-phenotype correlation associated with mismatch repair genes pathogenic variants. Retrospective review of medical records of 31 individuals with LS, 20 affected with colorectal cancer and 11 unaffected with family history of cancers, referred from January 2017 until August 2020. The prevalence of LS among affected and unaffected patients is 22% (20/92) and 2.2% respectively. Among affected individuals, MLH1 and MSH2 genes were highly frequent while for unaffected individuals, a recurrent PMS2 pathogenic variant was reported in several related individuals suggesting a tribal effect. This study highlights the epidemiology of LS in high-risk cohort in Qatar which helps to provide recommendations on genetic testing, and personalize surveillance and management programs

Worldwide prevalence of Lynch syndrome in patients with colorectal cancer: Systematic review and meta-analysis

PURPOSE

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome, with an estimated prevalence of 2% to 3% of CRC. A prevalence study is needed to provide accurate estimates of the true prevalence of LS.

METHODS

MEDLINE (Ovid), Embase, and Web of Science were searched. Prevalence was calculated by random effects meta-analysis models. I² score was used to assess heterogeneity across studies. Meta-regression was performed for between-study variance.

RESULTS

A total of 51 studies were included in this review. The overall pooled yield of LS screening was 2.2% based on all methods of detection. Studies performing germline tests on all participants with CRC reported higher prevalence (5.1%) as opposed to studies only performing germline tests on participants with tumors with mismatch repair deficiency (1.6%) or microsatellite instability (1.1%). Selected cohorts of CRC had a higher prevalence of germline LS diagnoses.

CONCLUSION

LS prevalence across multiple ethnic, geographic, and clinical populations is remarkably similar. Universal germline testing of patients presenting with cancer identifies that most CRCs are attributed to LS. Young patients presenting with CRC and those who fulfill criteria for a familial risk provide the highest returns for LS identification. Our study supports the universal germline CRC screening for LS.

Epidemiology of cancer in Saudi Arabia thru 2010-2019: a systematic review with constrained meta-analysis

Background

Cancer is emerging as a major global health-care system challenge with a growing burden worldwide. Due to the inconsistent cancer registry system in Saudi Arabia, the epidemiology of cancer is still dispersed in the country. Consequently, this review aimed to assemble the epidemiological metrics of cancer in Saudi Arabia in light of the available published data during the period from (2010–2019).

Methods

Published literature from Saudi Arabia relating to cancer incidence, prevalence, risk factors, and other epidemiological metrics were accessed through electronic search in Medline/PubMed, Cochrane, Scopus, Web of Knowledge, Google Scholar, and public database that meet the inclusion criteria. Relevant keywords were used during the electronic search about different types of cancers in Saudi Arabia. No filters were used during the electronic searches. Data were pooled and odds ratios (ORs) and 95% confidence interval (95%CI) were calculated. A random-effects meta-analysis was performed to assess the well-determined risk factors associated with different types of cancers.

Results

The most common cancers in Saudi Arabia are breast, colorectal, prostate, brain, lymphoma, kidney and thyroid outnumbering respectively. Their prevalence rates and OR (95%CI) as follow: breast cancer 53% and 0.93 (0.84–1.00); colon-rectal cancer (CRC) 50.9% and 1.2 (0.81–1.77); prostate cancer 42.6% and 3.2 (0.88–31.11); brain/Central Nervous System cancer 9.6% and 2.3 (0.01–4.2); Hodgkin and non-Hodgkin's lymphoma 9.2% and 3.02 (1.48–6.17); kidney cancer 4.6% and 2.05 (1.61–2.61), and thyroid cancer 12.9% and 6.77 (2.34–19.53).

Conclusion

Within the diverse cancers reported from Saudi Arabia, the epidemiology of some cancers magnitude 3-fold in the latest years. This increase might be attributed to the changing in the Saudi population lifestyle (adopting western model), lack of cancer awareness, lack of screening & early detection programs, social barriers toward cancer investigations. Obesity, genetics, sedentary lifestyle, tobacco use, viral infection, and iodine & Vit-D deficiency represent the apparent cancer risk factors in Saudi Arabia.