Lower prevalence of Lynch syndrome in colorectal cancer patients in a Japanese hospital-based population

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.

Microsatellite instability is biased in Amsterdam II-defined Lynch-related cancer cases with family history but is rare in other cancers: a summary of 1000 analyses

Background

Microsatellite instability (MSI) is a key marker for predicting the response of immune checkpoint inhibitors (ICIs) and for screening Lynch syndrome (LS).

Aim

This study aimed to see the characteristics of cancers with high level of MSI (MSI-H) in genetic medicine and precision medicine.

Methods

This study analyzed the incidence of MSI-H in 1000 cancers and compared according to several clinical and demographic factors.

Results

The incidence of MSI-H was highest in endometrial cancers (26.7%, 20/75), followed by small intestine (20%, 3/15) and colorectal cancers (CRCs)(13.7%, 64/466); the sum of these three cancers (15.6%) was significantly higher than that of other types (2.5%)(P < 0.0001). MSI-H was associated with LS-related cancers (P < 0.0001), younger age (P = 0.009), and family history, but not with smoking, drinking, or serum hepatitis virus markers. In CRC cases, MSI-H was significantly associated with a family history of LS-related cancer (P < 0.0001), Amsterdam II criteria [odds ratio (OR): 5.96], right side CRCs (OR: 4.89), and multiplicity (OR: 3.31). However, MSI-H was very rare in pancreatic (0.6%, 1/162) and biliary cancers (1.6%, 1/64) and was null in 25 familial pancreatic cancers. MSI-H was more recognized in cancers analyzed for genetic counseling (33.3%) than in those for ICI companion diagnostics (3.1%)(P < 0.0001). Even in CRCs, MSI-H was limited to 3.3% when analyzed for drug use.

Conclusions

MSI-H was predominantly recognized in LS-related cancer cases with specific family histories and younger age. MSI-H was limited to a small proportion in precision medicine especially for non-LS-related cancer cases.

Staging the tumor and staging the host: A two centre, two country comparison of systemic inflammatory responses of patients undergoing resection of primary operable colorectal cancer

BACKGROUND

How systemic inflammation-based prognostic scores such as the modified Glasgow Prognostic Score (mGPS) and neutrophil:lymphocyte ratio (NLR) differ across populations of patients with colorectal cancer (CRC) remains unknown. The present study examined the mGPS and NLR in patients from United Kingdom (UK) and Japan.

METHODS

Patients undergoing resection of TNM I-III CRC in two centres in the UK and Japan were included. Differences in clinicopathological characteristics and mGPS (0-CRP≤10 mg/L, 1-CRP>10 mg/L, 2-CRP>10 mg/L, albumin<35 g/L) and NLR (≤5/>5) were examined.

RESULTS

Patients from UK (n = 581) were more likely to be female, high ASA and BMI, present as an emergency (all P < 0.01) and have higher T stage compared to those from Japan (n = 559). After controlling for differences in tumor and host characteristics, patients from Japan were less likely to be systemically inflamed (OR: mGPS: 0.37, 95%CI 0.27-0.50, P < 0.001; NLR: 0.53, 95%CI 0.35-0.79, P = 0.002).

CONCLUSION

Systemic inflammatory responses differ between populations with colorectal cancer. Given their prognostic value, reporting of systemic inflammation-based scores should be incorporated into future studies reporting patient outcomes.

Prevalence of Lynch syndrome and Lynch-like syndrome among patients with colorectal cancer in a Japanese hospital-based population

Objective

We investigated the prevalence of Lynch syndrome and Lynch-like syndrome among Japanese colorectal cancer patients, as there have been no credible data from Japan.

Methods

Immunohistochemical analyses for mismatch repair proteins (MLH1, MSH2, MSH6 and PMS2) were carried out in surgically resected, formalin-fixed paraffin-embedded specimens obtained from 1,234 newly diagnosed colorectal cancer patients between March 2005 and April 2014. The presence/absence of the BRAF V600E mutation and hypermethylation of the MLH1 promoter was analyzed where necessary. Genetic testing was finally undertaken in patients suspected as having Lynch syndrome.

Results

By the universal screening approach with immunohistochemical analysis for mismatch repair proteins followed by analyses for the BRAF V600E mutation and MLH1 promoter methylation status, 11 (0.9%) of the 1,234 patients were identified as candidates for genetic testing. Out of the 11 patients, 9 (0.7%) were finally diagnosed as having Lynch syndrome; the responsible genes included MLH1 (n = 1), MSH2 (n = 4), EPCAM (n = 1) and MSH6 (n = 3). The remaining two patients (0.2%) were regarded as having Lynch-like syndrome, since biallelic somatic deletion of the relevant mismatch repair genes was detected in the absence of germline mismatch repair alterations. None of the cases was identified as having germline MLH1 epimutation.

Conclusions

The prevalence of Lynch syndrome among all newly diagnosed cases of colorectal cancer in Japan is in the same range as that recently reported by studies in Western population. The prevalence of Lynch-like syndrome seems to be extremely low.

Management strategies in Lynch syndrome and familial adenomatous polyposis: a national healthcare survey in Japan

Lynch syndrome (LS) and familial adenomatous polyposis (FAP) are major sources of hereditary colorectal cancer (CRC) and are associated with other malignancies. There is some heterogeneity in management strategies in Japan. We undertook a survey of management of hereditary CRC in hospitals that are members of the Japan Society of Colorectal Cancer Research. One hundred and ninety departments responded, of which 127 were from designated cancer care hospitals (DCCHs) according to the Japanese government. There were 25 488 operations for CRC in these departments in 2015. The DCCHs performed better with regard to usage of Japan Society of Colorectal Cancer Research guidelines, referring new CRC patients for LS screening, and having in‐house genetic counselors and knowledge of treatment for LS. There were 174 patients diagnosed with LS and 602 undergoing follow‐up in 2011–2015, which is fewer than the number expected from CRC operations in 2015. These numbers were not affected by whether the institution was a DCCH. Universal screening for LS was carried out in 8% of the departments. In contrast, 541 patients were diagnosed with FAP and 273 received preventive proctocolectomy/colectomy in 2011–2015. The DCCH departments undertook more surgery than non‐DCCH departments, although most of the management, including surgical procedures and use of non‐steroidal anti‐inflammatory drugs, was similar. Management of desmoid tumor in the abdominal cavity differed according to the number of patients treated. In conclusion, there was heterogeneity in management of LS but not FAP. Most patients with LS may be overlooked and universal screening for LS is not common in Japan.

Prevalence and clinicopathologic/molecular characteristics of mismatch repair-deficient colorectal cancer in the under-50-year-old Japanese population

PURPOSE

To clarify the prevalence and clinicopathologic/molecular characteristics of mismatch repair (MMR)-deficient colorectal cancer in the young Japanese population.

METHODS

Immunohistochemical analyses for MMR proteins (MLH1, MSH2, MSH6, and PMS2) were performed in formalin-fixed paraffin-embedded sections prepared from the resected CRC specimens of 119 consecutive patients aged <50 years old, who underwent resection of the primary tumor at our institution between 1996 and 2015. Analyses for somatic BRAF V600E mutation, somatic hypermethylation of the MLH1 promoter, and germline MMR gene mutations were undertaken where indicated.

RESULTS

MMR protein loss was found in 10 patients (8.4%), 7 (5.9%) of whom were subsequently identified to have Lynch syndrome (LS). The remaining 3 patients were categorized as having sporadic MMR-deficient CRC (n = 2) or "possible LS (n = 1)". In multivariate logistic regression analysis, the presence of tumor-infiltrating lymphocytes (P < 0.01), right-sided location of the tumor (P = 0.01), and a history of LS-associated tumors in the first-degree relatives (P < 0.01) were identified as independent factors predictive of MMR-deficient CRC.

CONCLUSION

These results are of value in the clinical management of patients with the early onset CRC under circumstances where universal tumor screening approaches for LS are still not available, like in Japan.

Association between the age and the development of colorectal cancer in patients with familial adenomatous polyposis: a multi-institutional study

PURPOSE

To investigate the incidence of colorectal cancer among familial adenomatous polyposis (FAP) patients by phenotype using the latest modalities.

METHODS

We collected data on 303 patients who underwent surgery for FAP at one of 23 institutions between 2000 and 2012. The incidence of colorectal cancer was investigated by phenotype.

RESULTS

Colorectal cancer was diagnosed in 115 (38.0 %) of the 303 patients. Overall, colorectal cancer with the attenuated, sparse, and profuse phenotypes was diagnosed at 30, 31, and 28 years of age, respectively, in 10 % of the patients and at 59, 48, and 41 years of age, respectively, in 50 % of the patients (P = 0.013). The patients with colorectal cancer were older than those without colorectal cancer for all phenotypes. The optimal cut-off age for predicting the development of colorectal cancer in the attenuated, sparse, and profuse phenotypes was 46, 31, and 27 years, respectively.

CONCLUSIONS

Patients with profuse and sparse phenotypes should undergo prophylactic proctocolectomy before their mid-to-late 20 s. On the other hand, the timing and type of surgery for patients with attenuated FAP (AFAP) should be decided individually with reference to the colonoscopic findings.

Hereditary gastrointestinal cancer

Gastrointestinal (GI) cancer, including gastric and colorectal cancer, is a major cause of death worldwide. A substantial proportion of patients with GI cancer have a familial history, and several causative genes have been identified. Gene carriers with these hereditary GI syndromes often harbor several kinds of cancer at an early age, and genetic testing and specific surveillance may save their lives through early detection. Gastroenterologists and GI surgeons should be familiar with these syndromes, even though they are not always associated with a high penetrance of GI cancer. In this review, we provide an overview and discuss the diagnosis, genetic testing, and management of four major hereditary GI cancers: familial adenomatous polyposis, Lynch syndrome, hereditary diffuse gastric cancer, and Li-Fraumeni syndrome.