Multicentric study for estimation of prevalence of microsatellite instability and Lynch syndrome amongst colorectal cancer patients in India

doi:10.21203/rs.3.rs-2361537/v1

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Multicentric study for estimation of prevalence of microsatellite instability and Lynch syndrome amongst colorectal cancer patients in India

https://doi.org/10.21203/rs.3.rs-2361537/v1

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Purpose

Colorectal cancer (CRC) is the fifth most common cancer in India, however, there is a paucity of systematically collected data related to its molecular epidemiology, specifically related to tumour microsatellite instability (MSI) and Lynch syndrome prevalence.

Methods

We prospectively recruited 207 unrelated patients who were diagnosed with CRC from whom primary tumour biopsy along with a matched blood sample was obtained. A sequential genetic testing approach for Lynch syndrome detection in colorectal cancer patients in accordance with the UK’s National Institute of Health and Care Excellence’s guideline (DG27) was utilised. Briefly, DNA from tumour biopsies were tested for MSI status followed BRAF V600E testing in samples which showed MSI-high result. Germline testing for the mismatch repair genes was carried in patients who had MSI-high and BRAF V600E negative tumours. Seventeen patients recanted their consent to participate in the study and therefore, results from 190 out of 207 patients is presented here.

Results

Mean age at cancer diagnosis across the cohort was 52.3 years with male to female ratio of 2:1 and 57.3% of the patients had tumours in the descending colon or rectum. MSI-high status was observed in 79 patients (42.6%) and, was inversely associated with age (OR = 0.95, 95% CI = 0.92–0.97, p = < 0.001) and cancers in distal colon and rectum (OR = 0.42, 95% CI = 0.22–0.81, p = 0.009 for distal colon; OR = 0.13, 95% CI = 0.04–0.40, p < 0.001 for rectum). Of these, 76 patients had BRAF V600E negative mutation status (96%) and of these, 48 were diagnosed with Lynch syndrome (63%; MLH1 = 38, MSH2 = 4, MSH6 = 4, PMS2 = 1, EPCAM = 1). The variants c.154del and c.306G > T in the MLH1 gene were most commonly observed across Lynch syndrome patients in our cohort.

Conclusions

This is the first systematic evaluation of the molecular epidemiology of CRC in India. We observe a high proportion of patients with young onset CRC coupled with high prevalence of MSI-high status and Lynch syndrome. The study provides a unique opportunity to explore development of novel Lynch syndrome detection and cancer prevention pathway in Indian healthcare settings.

Colorectal cancer

microsatellite instability

Lynch syndrome

India

prevalence

Colorectal cancer (CRC) is the fifth most common cancer in India, accounting for 4.9% of 1.3 million new cases and 4.2% of all cancer related deaths in 2020 ¹. A small number of monogenic cancer predisposition syndromes account for approximately 3–5% of all CRC cases worldwide, of which Lynch syndrome (LS) is the most common hereditary CRC syndrome ². LS is an autosomal dominant cancer predisposition syndrome which is caused due to germline loss of function variants in mismatch repair genes, chiefly, MLH1, MSH2, MSH6, PMS2 and EPCAM. The World Health Organisation estimates its prevalence at approximately 1 in 125 (95% CI: 1 in 100–180) in the general population ³, making it a significant priority to detect LS carriers for healthcare settings in order to prevent cancer.

Microsatellite instability (MSI) is a molecular phenotype of LS tumours whereby spontaneous insertions or deletions occur in the repetitive tracts of the DNA. Tumour exhibiting MSI (also called as MSI-high tumours) arise through disruption of the mismatch repair (MMR) mechanism. Due to the clinical utility of MSI and LS status, the latest National Institute of Health and Care Excellence (NICE) guidelines in the UK recommends carrying out universal MSI testing in CRC patients followed by germline MMR gene sequencing in patients with MSI-high and BRAF V600E/ MLH1 gene hypermethylation negative tumours ⁴. Furthermore, the National Institute of Health Research’s health technology assessment suggests universal MSI testing followed by germline testing for LS identification in CRC patients to be cost-effective ⁵.

These recommendations were based on the epidemiological data of CRC patients of European/ non-Hispanic white ethnicities, whereby MSI phenotype and LS is reported to occur in approximately 15% and 3%, respectively ⁶. In contrast, global prevalence of CRC suggests significant variation between populations of Europe, North America, Australia and Asia with lower prevalence in Asian compared to European populations ². Furthermore, significant difference in the LS positivity rate during germline screening by geographic region and, an inverse correlation between LS screening positivity and 5-year CRC prevalence is observed ². Specifically, CRC patients from the Indian subcontinent are observed with one of the highest MSI and LS positivity rates ^{2, 7}, although these observations were made in small cohorts.

Therefore, in the present study, we conducted a systematic assessment of the prevalence of MSI molecular phenotype and LS amongst 207 CRC patients from Indian subcontinent. By carrying out the genetic testing strategy as suggested by the NICE guidelines, we provide evidence for higher prevalence of MSI and LS in the Indian population, which further supports the need to conduct universal MSI testing in all CRC patients of Indian.

Study population

A total of 207 unrelated patients diagnosed with CRC were recruited from 14 centres between 2019 and 2022. Clinical parameters such as age at diagnosis, tumour site and histopathology together with family history details were collected for all patients. Tumour site was divided as follows: (a) Right sided or proximal colon which includes caecum, ascending colon and hepatic flexure, (b) transverse colon, (c) left sided or distal colon which included splenic flexure, descending colon and sigmoid colon and, (d) rectum. Written informed consent was collected from all patients in accordance with the Helsinki declaration. This study was approved by the Ethics Committee at FRIGE’s Institute of Human Genetics, Ahmedabad and CIMS Hospital, Ahmedabad.

Sample collection and DNA extraction

Formalin fixed paraffin embedded (FFPE) treated or fresh frozen biopsy of CRC tissues together with matched normal blood sample were collected from all participating patients. DNA extraction from FFPE and fresh tumour biopsy was carried out using QIAmp DNA FFPE Tissue kit and QIAmp DNA Fresh Tissue kit (Qiagen, Germany), respectively, as per the manufacturer’s protocol. Genomic DNA from the peripheral blood sample was extracted using desalting method ⁸. Quantity of the DNA from tumour and blood samples were measured using QIAxpert spectrophotometer (Qiagen, Germany) and Qubit HS dsDNA kit (Thermo Fisher, USA). MSI, BRAF V600E and germline Lynch syndrome testing pathway was carried out in accordance with the latest NICE guidelines for detection of Lynch syndrome in patients with colorectal cancer (DG27) ⁴.

MSI by fragment length analysis

MSI analysis in all tumour samples was carried out using either Promega MSI Analysis v1.2 kit (Promega, USA) or TrueMark MSI Assay kit (Thermo Fisher, USA). For both kits, DNA from tumour together with matched normal sample was amplified according to the manufacturer’s protocol and the amplicons were then processed on the ABI SeqStudio platform (Applied Biosystems, USA) for fragment length analysis using ILS600 as the internal size control marker. Data from the SeqStudio instrument were analysed using GeneMapper V5 software when using the Promega MSI Analysis v1.2 kit and TrueMark MSI Analysis software when utilising TrueMark MSI Assay kit.

Using Promega MSI v1.2 kit, MSI status was called based on the presence or absence of MSI across 5 polymorphic markers. A sample was called as microsatellite stable (MSS) if none or only 1 of the markers were unstable whereas a sample was called microsatellite unstable (MSI-high) if 2 or more markers were unstable. In contrast, using TrueMark MSI Assay kit, MSI status was called based on the presence or absence of MSI across 13 polymorphic markers (including the Bethesda panel). A sample was called as MSS if 2 or less than 2 markers were unstable whereas, a sample was called MSI-high if 3 or more markers were unstable.

BRAF V600E mutation analysis

In all MSI-high tumour samples, BRAF V600E somatic mutation analysis was carried out in tumour DNA using Qiagen’s BRAF RGQ PCR kit (Qiagen, Germany) according to the manufacturer’s protocol. Briefly, the targeted variants (V600E, V600K, V600R and V600D) are amplified with mutation specific primers and detection of amplification is performed using probes containing a fluorophore and a quencher. Variant was reported according to the HGVS guidelines for mutation nomenclature and according to the reference sequence NM_004333.4.

Germline DNA sequencing for detection of Lynch syndrome

Targeted germline gene sequencing was carried out in patients with MSI-high and BRAF V600E negative tumours. This included selective capture and sequencing of the protein coding regions of genes which are previously associated with hereditary tumour predisposition syndromes. Sequencing libraries were prepared and sequenced to a mean coverage of approximately 100-400x on the Illumina sequencing platforms (Illumina, USA). FastQ files for each sample were aligned against the human reference genome build hg38/GCRh38.p13 using BWA v.0.7 ⁹, followed by sorting, indexing and duplicates removal by samtools ¹⁰. Base quality score recalibration and single nucleotide and indel variants were called using GATK v.4.1.2 ¹¹ in accordance with the GATK’s best practice guidelines. Annotation of variants was performed using the VEP program against the Ensembl release 99 human genome model ¹². Copy number variants (CNVs) were detected from targeted sequencing data using the ExomeDepth v1.1.10 ¹³. Briefly, clinically relevant variants were annotated using databases such as ClinVar, InSiGHT, OMIM, GWAS, HGMD, LOVD and SwissVar. Common variants were filtered based on the minor allele frequency in the 1000Genome Phase 3, gnomAD, EVS and dbSNP databases. Non-synonymous variant effects were estimated using multiple in silico algorithms such as CADD ¹⁴, FATHMM ¹⁵, PolyPhen-2 ¹⁶, SIFT ¹⁷ and MutationTaster2 ¹⁸. Only non-synonymous, splice site and critical non-coding variants were used for clinical interpretation.

Validation of the variant(s) in one of the MMR genes which were identified by the germline DNA sequencing was carried out using Sanger sequencing for single nucleotide variants and Q-PCR for CNVs (Supplementary Table 1).

Statistical analysis

The odds ratio (OR) and 95% confidence intervals (95% CI) for associations between clinical features and MSI status were assessed using logistic regression model. A two-sided p-value of < 0.05 was considered statistically significant. All data were analysed using Stata V14 (Stata Corp, USA). Anonymised clinical, MSI and germline Lynch syndrome results are available in Supplementary File 1.

Clinical and anthropometric details of CRC patient cohort

A total of 207 patients with a clinical history of CRC were consecutively recruited on the study. Of these, 17 patients recanted their consent to participate in the study, and hence their data were removed from further analyses.

Of 207 patients, 190 patients were analysed for MSI, BRAF V600E mutation status and germline Lynch syndrome status. Clinical details of these patients are presented in Table 1. The average age at diagnosis was 52.3 years and the male to female ratio was observed at approximately 2:1. Analysis of recruitment stratified by study site suggested no significant recruitment bias by a given site (Supplementary Fig. 1), therefore it is plausible either that the lower age of cancer diagnosis in our current cohort could be due to an enhanced interest by patient to understand their cause of cancer or cancer epidemiology in general across the population. Approximately 57% of the patients had cancer in distal colon or rectum and 7.9% of the patients had synchronous or metachronous cancer. Interestingly, 26.8% of the patients had family history of cancer whereby either their first degree relative had a history of cancer at less than 50 years of age or their first- and second-degree relatives were diagnosed with one of the Lynch syndrome associated cancers regardless of age at diagnosis (Table 1).

Table 1

Clinical details and association between MSI status and age, sex and cancer site of 190 CRC patients.
Clinical/ anthropometric details	Mean (SD)/ n (%)	MSS (n (%); n = 111)	MSI-high (n (%); n = 79)	Odds Ratio	95% Confidence Interval	p-value
Age at diagnosis	52.3 (14.2)
<= 25 years	6 (3.2)	3 (2.7)	3 (3.8)	Reference	-	-
> 25 and < = 50 years	80 (42.1)	35 (31.5)	45 (57)	1.29	0.24–6.76	0.77
> 50 and < = 75 years	96 (50.5)	66 (59.5)	30 (38)	0.45	0.09–2.38	0.35
> 75 years	8 (4.2)	7 (6.3)	1 (1.3)	0.14	0.01–1.99	0.15
Sex
Female	56 (29.5)	34	22	Reference	-	-
Male	134 (70.5)	77	57	1.14	0.61–2.16	1.14
Cancer site
Proximal colon	70 (36.8)	30 (27)	40 (50.6)	Reference	-	-
Transverse colon	11 (5.8)	5 (4.5)	6 (7.6)	0.9	0.25–3.22	0.87
Distal colon	81 (42.6)	52 (46.9)	29 (36.7)	0.42	0.22–0.81	0.009
Rectum	28 (14.7)	24 (21.6)	4 (5.1)	0.13	0.04–0.40	< 0.001
Synchronous or metachronous cancer
No	175 (92.1)	106	69	Reference	-	-
Yes	15 (7.9)	5	10	3.07	1.01–9.37	0.05
Family history of cancer*
No	129 (67.9)	86	43	Reference	-	-
Yes	51 (26.8)	18	33	3.67	1.86–7.25	< 0.001
Detail not available	10 (5.3)	7	3	-	-	-
* Family history of cancer is defined as first degree relative with history of cancer at < 50 years of age or first and second degree relatives with one of the Lynch syndrome associated cancers regardless of age at diagnosis.

Tumour MSI and BRAF V600E status

MSI analysis showed MSI-high status to be present in 79 patients (40.7%). The presence of MSI-high status was inversely associated with age at cancer diagnosis whereby an increase in age by 1 year was associated with 5% reduction in probability of MSI-high tumour (OR = 0.95, 95% CI = 0.93–0.98, p = < 0.001; Fig. 1A). In congruence with the literature, probability of detecting MSI-high tumour was significantly lower in distal colon (p = 0.009) or rectum (p < 0.001) compared to proximal colon, and was significantly higher in patients with synchronous/ metachronous cancer (p = 0.05) and patients with family history of cancer (p < 0.001) (Table 1, Fig. 1B). No association between MSI-high tumour status and sex was observed.

BRAF p.V600E somatic mutation analysis was carried out in 76 of 79 patients (96%) with MSI-high tumour status, as in the 3 patients, DNA quality was insufficient to carry out the BRAF gene analysis. Of 76 patients, 72 (94.7%) did not have the variant where 4 patients (5.3%) had the p.V600E variant in the tumour DNA.

Germline DNA testing for identification of Lynch syndrome in MSI-high and BRAF V600E negative patients

In all patients with MSI-high and BRAF p.V600E negative patients (n = 76), germline DNA sequencing was carried out to identify likely Lynch syndrome mutation carriers. Of these, 48 patients (63%) were detected with a pathogenic/ likely pathogenic variant in one of the 5 MMR genes (MLH1 = 38, MSH2 = 4, MSH6 = 4, PMS2 = 1, EPCAM = 1; Supplementary Table 2). Furthermore, germline DNA sequencing was also carried out in 4 patients who had MSS tumour status but a family history of cancer. All of these patients were identified with a pathogenic/ likely pathogenic variant in the MLH1 gene (Supplementary Table 2). Presence of a germline pathogenic variant in MMR genes despite having an MSS tumour phenotype is a known occurrence in approximately 2% of CRCs, an observation which is in congruence within our cohort. Therefore, 27.4% of all CRC patients in the current cohort were diagnosed to be Lynch syndrome carriers, a significant difference compared to the proportion reported in the published literature ^{2, 6}.

Interestingly, variants c.154del and c.306G > T in the MLH1 gene were most commonly observed across Lynch syndrome patients in our cohort (Fig. 2). This suggests that both of these variants are likely to be founder variants in our cohort, however, assessment of the founder mutation status using haplotype analysis was beyond the scope of the study.

Significant variation in the incidence rate of CRC exists around the world and the factors leading to it are still unclear, although, certain factors may include varying genetic composition, diet intake, gut microbiota composition and implementation of screening programs for early detection of CRC ¹⁹. Previous studies in the Indian population has demonstrated higher rates of MSI compared to European/ non-Hispanic white patients ^{2, 7}. In our study, we systematically studied the prevalence of MSI and LS across 190 unrelated CRC patients in India. We show a significant association between MSI status and Lynch syndrome positivity rates with age at diagnosis, tumour location and family history of cancer. Furthermore, we observe a strong association of MSI and Lynch syndrome positivity rate with proximal colon cancer site.

In our study, average age of diagnosis of CRC was 52.3 years, which is significantly lower than that reported in patients of European/ non-Hispanic white ethnicity. Interestingly, the observation is in congruence with the recent data reported from tertiary centres which reported mean age of presentation at 47.7 years across 970 CRC patients ^20–22. Intriguingly, the study by Deo et al. in Indian population observed a higher proportion of patients with age at diagnosis of < 40 years with rectal cancer (41.3%) compared to colon cancer (25.4%) ²⁰. In contrast to this observation, our study didn’t observe significant difference in the mean age of diagnosis by cancer site (Proximal colon = 50.3 ± 13.2 years; transverse colon = 49 ± 14.5 years; distal colon = 55.5 ± 14.4 years and; rectum = 49.3 ± 14.6 years). Nonetheless, a consistent observation of young age at diagnosis of cancer is coupled with a substantial rise of 20.6% in the rates of CRC between 2004 and 2014 across India, with the highest increase of 60.7% observed in Kolkata ²². This has substantial implications for planning and deployment of screening strategies. For example, in the UK, Europe and USA, guidelines now recommend initiating colonoscopic surveillance in individuals from the age of 50 years, regardless of family history, in order to identify colorectal neoplasms ²³. With an average lower age of diagnosis and a significant increase in rates of CRC across India, an earlier age limit for initiation of colonoscopic surveillance could likely help towards earlier detection of cancer or cancer prevention.

The identification of Lynch syndrome has traditionally relied upon screening via clinical criteria such as Amsterdam or Revised Bethesda guidelines which incorporates information on family history of cancer to delineate the probability of an individual being a Lynch syndrome carrier ²⁴. Based on this, the National Comprehensive Cancer Network (NCCN) and the US Multi-Society Task Force on CRC published guidelines which recommend germline genetic evaluation of any individual if the predicted risk of being a Lynch syndrome carrier is 5% or higher using any one of the 3 prediction models: MMRPro, MMRPredict and PREMM ²⁴. However, this approach is seldom used in clinical practice worldwide due to its low clinical utility as it fails to capture the entire spectrum of Lynch syndrome patients, especially patients with low variants in low penetrance genes such as MSH6 and PMS2²⁴. Indeed, the current NICE guideline recommends universal MSI testing across all CRC patients in order to identify Lynch syndrome patients due to its superior sensitivity and specificity ⁴. Despite this, anecdotal evidence suggests that the uptake of universal MSI testing in India is low due to high cost associated with MSI testing which borne by the patient. Therefore, clinical utility of aforementioned prediction models for Lynch syndrome detection could be conceivable in the Indian population considering 90% of the patients in our cohort have variants in high penetrance MLH1 and MSH2 genes, against which these models have high sensitivity and specificity. Although, a study assessing their utility would be required for Indian CRC patients.

Interestingly, we observed a high proportion of Lynch syndrome patients in our cohort with variants c.154del and c.306G > T in the MLH1 gene. Considering that these variants were observed in unrelated individuals, they are likely to be founder mutations. Founder mutations in specific populations are commonly observed in several Mendelian disorders. They are shared by apparently unrelated individuals which inherited the mutation from a common ancestor hundred to thousands of years ago. At least 50 founder mutations have been identified in MMR genes to date with the most evident example being two founder variants c.454-1G > A and exon 16 deletion in the MLH1 gene, which together accounts for 50% of all Lynch syndrome patients observed in Finland ²⁵. It is well known that analysing a particularly frequent founder mutation is the first step towards low-cost Lynch syndrome screening as it avoids expensive germline testing in a significant number of samples. To the best of our knowledge, no common founder mutation has yet been identified in the Indian population. Whilst our observation is intriguing, proving c.154del and c.306G > T as founder variants using a combination of haplotype analyses in case-control cohort is beyond the scope of the current study.

The high positivity rates of MSI and Lynch syndrome amongst our cohort has significant clinical implications. For example, the latest long-term follow-up results from the CAPP2 randomised controlled trial in Lynch syndrome patients suggests a 50% risk reduction of CRC in patients randomised to aspirin at 20 years follow-up ²⁶. In addition, a 50% reduction in risk of upper gastrointestinal cancers, particularly- stomach, liver and pancreas- was observed in Lynch syndrome patients randomised to resistant starch at 20 years follow-up ²⁷. Indeed, the NICE now recommends regular intake of low-dose aspirin in patients identified to be Lynch syndrome carriers in the UK, in order to reduce risk of CRC ²⁸. In contrast, the current ICMR guidelines do not recommend universal MSI testing and limits germline testing for Lynch syndrome in patients with strong family history of cancer ²⁹. Our results provide evidence towards application of universal MSI testing and germline Lynch syndrome testing, regardless of age or family history of cancer, in Indian patients with MSI-high and BRAF V600E negative CRC.

Whilst our study observations are, in most parts, in congruence with the reported literature, it has some limitations too. First, we utilised the published NICE pathway for carrying out molecular genetic testing in tumour and germline ⁴. Whilst the pathway is designed to identify Lynch syndrome patients primarily on the molecular phenotype of tumour (i.e. MSI-high and BRAF V600E negative), we did observe germline MMR gene mutation in patients with MSS tumours. This is in congruence with the published literature whereby approximately 2% of patients with MSS CRC tumours are observed with germline mutations in MMR genes ³⁰. With the germline testing being restricted to patients with a strong family history of cancer in our cohort, we could not explore the prevalence of Lynch syndrome amongst patients with MSS CRC tumour regardless of age and family history. Second, we couldn’t record detailed histological features of tumour biopsies. Typical histological features of Lynch syndrome based colorectal cancers includes a combination of the presence of tumour infiltrating lymphocytes, Crohn like peritumoural lymphoid aggregates, poor differentiation, areas of mucinous or signet ring cell component and medullary growth pattern ³¹. Exploration of association between certain histological features of tumour and germline mutation in MMR gene could be intriguing since it could provide indirect source of evidence for a patient likely being a Lynch syndrome carrier. Third, an element of referral bias could be present since the patients were recruited at tertiary care hospitals rather than data being captured from population-based cancer registries. This could lead to preferential selection of patients with family history of cancer or synchronous/ metachronous cancer. Indeed, we observed 7.9% of patients with synchronous/ metachronous cancer in our study. In contrast, a recent epidemiological study of colorectal cancer patients from a tertiary care hospital in India observed 2.2% of the patients with a synchronous cancer ²⁰. We could not reconcile this disparity during our study due to the lack of access to the overall number of patients treated at each given study site in the study during the study period. Nonetheless, our Lynch syndrome yield are similar to those reported in a recent meta-analysis by John et al. for CRC patients from the Indian subcontinent ². High quality data can be generated high population coverage and structured data collection, unfortunately major low-middle income countries lack high quality cancer registry programs and mostly gather basic demographic data rather than longitudinal and genetic data which are crucial to delineating epidemiology and planning future strategies for screening, diagnosis, treatment and prevention.

This is the first study from India to provide a systematic assessment of the prevalence of MSI and Lynch syndrome across colorectal cancer. With a significantly high rates of MSI and Lynch syndrome coupled with an increasing rate of colorectal cancer incidence across the Indian population, this study provides the first evidence for application of universal MSI testing and germline Lynch syndrome testing in MSI-high and BRAF V600E negative patients. Lastly, the results of this study provide an opportunity to explore long term follow-up studies in Lynch syndrome patients and develop methods for cancer prevention suitable for low-income healthcare settings like India.

CRC= colorectal cancer, MSI-high= microsatellite instability, MSS= microsatellite stable, LS= Lynch syndrome, NICE= National Institute of Health and Care Excellence, OR= Odds Ratio, CI= Confidence Interval.

Ethics approval and consent to participate

Written informed consent was collected from all patients. All experimental method were carried out in accordance with the Helsinki declaration. This study was approved by the Ethics Committee at FRIGE’s Institute of Human Genetics, Ahmedabad and CIMS Hospital, Ahmedabad.

Consent for publication

Not applicable.

Availability of data and materials

All data generated or analysed during this study are included in this published article as Supplementary File 1. FASTQ files from germline sequencing are available from the EMBL-EBI European Nucleotide Archive, accession number PRJEB58813 (ERP143889).

Acknowledgement

We thank all participating patients and their family members. Their participation would greatly aid the progress of Indian medical science towards cancer prevention.

Competing interests

All authors declare that they have no competing interests.

Funding

This study was funded by the Gujarat State Biotechnology Mission grant (GSBTM/JDR&D/604/2019/299) to Harsh Sheth.

Author’s contributions

HS, JS, FS, ST, JB and JE conceived the idea for this study. AJ, MS, PS, SA, LT, VDY, AT, CS, BT, DB, MG, TP, NP, AP, RP, RG, and CtS carried out patient recruitment. HS, CP, PrS, VR and AUM carried out laboratory work. HS and AJ carried out data analysis and interpretation. HS and AJ wrote the manuscript. All authors approved the final version of the manuscript.

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No competing interests reported.

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Multicentric study for estimation of prevalence of microsatellite instability and Lynch syndrome amongst colorectal cancer patients in India

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Abstract

Purpose

Methods

Results

Conclusions

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Background

Materials And Methods

Study population

Sample collection and DNA extraction

MSI by fragment length analysis

Germline DNA sequencing for detection of Lynch syndrome

Statistical analysis

Results

Clinical and anthropometric details of CRC patient cohort

Discussion

Conclusion

Abbreviations

Declarations

References

Additional Declarations

Supplementary Files

Status:

Version 1