Advances in the study of Lynch syndrome in China

Risk for Hereditary Neoplastic Syndromes in Women with Mismatch Repair-Proficient Endometrial Cancer

Endometrial cancer (EC) is a prevalent malignancy in women, and those who are proficient in the DNA mismatch repair (pMMR) pathway may have a family history (FH) that meets the criteria for a hereditary neoplastic condition (HNS). This study aimed to estimate the risk of HNS in women with pMMR endometrial tumors by analyzing their FH. To achieve this, we collaborated with a primary study and collected FH information by telephone. The final sample comprised 42 women who responded to the Primary Screening Questionnaire. Their family pedigrees were drawn and categorized according to internationally standardized criteria for the risk of HNS. Results showed that 26 women (61%) were found to be at risk for HNS, with Bethesda criteria being met by 23%, Amsterdam criteria by 15%, and 4% met the attenuated familial adenomatous polyposis criteria. Our results emphasize the importance of FH and the need to encourage healthcare professionals to collect and document FH more frequently, even if it is self-reported. By identifying individuals with HNS, we can improve their outcomes and reduce the burden of cancer in families with a predisposition to cancer.

Lynch syndrome-associated repeated stroke with MLH1 frame-shift mutation

Lynch syndrome (LS) is an autosomal dominant inherited disease caused by germline mutations in DNA mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, and PMS2, which predisposes patients to various malignant neoplasms. Previous studies showed that MLH1, MSH2, MSH6, and PMS2 mutation in LS were associated with an elevated risk of colorectal, gastric, endometria, ovarian, and other cancers among family members. Patients of these kinds of cancers had high incidence of synchronous and metasynchronus. We describe the case of a 34-year-old female patient with 50 days of sudden dizziness and left limb weakness, whose head CT scan showed large infarction in the right frontal temporal parietal lobe and basal ganglia area. Imaging examinations and pathological biopsy indicated high-grade serous carcinoma (HGSC) IIIA1 of the right ovary. In addition, a novel frame-shift mutation in the MLH1 gene (c.1621dupG, p.A541Gfs*16) was found in the genetic panel sequence. It may render declining of MLH1 protein and also associate with the patient's progressive clinical manifestations of multiple systems. Therefore, the timely use of prenatal diagnosis to prevent unnecessary new cases of this severe genetic disease is available.

Distinct clinical phenotype and genetic testing strategy for Lynch syndrome in China based on a large colorectal cancer cohort

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) predisposition syndrome. We performed a large-scale study to assess a screening strategy for identifying LS in Chinese CRC patients in routine clinical testing. A total of 4,195 eligible CRCs were universally screened. Then, 8.7% of CRCs were detected with dMMR. The incidence of LS was 2.7% (115 of 4,195) in this cohort; among patients over 70 years of age, only 0.3% (2 of 678) were diagnosed as LS. Then, 17.4% of LS cases showed large genomic deletions/duplications. LS probands developed CRCs predominantly at proximal colon location. The frequency of BRAF V600E mutation among Chinese CRCs was significantly lower than that among Western populations, and MLH1 promoter methylation significantly improved the efficiency of genetic screening for LS among MLH1-deficient patients. A comprehensive molecular testing strategy that includes detection of large genomic rearrangements is imperative for the diagnosis of LS. Among CRC patients aged 70 years or younger, a selective strategy for LS screening might be considered for routine clinical testing.

Epidemiology and risk factors of colorectal cancer in China

In China, colorectal cancer (CRC) ranked fourth and fifth in the highest incidence and mortality rates of all malignancies in 2018, respectively. Although these rates are below the world average, China placed first worldwide in the number of new CRC cases and CRC-related deaths because of its comparatively large population. This disease represents a threat to the health of population and incurs a heavy economic burden on the society and individuals. CRC has various risk factors, including age, sex, lifestyle, genetic factors, obesity, diabetes, gut microbiota status, and precancerous lesions. Furthermore, incidence and mortality rates of CRC are closely related to socioeconomic development levels, varying according to regional and population characteristics. Prevention is the main strategy to reduce incidence and mortality rates of CRC. This can be achieved through strategies stimulating lifestyle changes, healthy diet habits, and early screening for high-risk individuals. To reduce the burden of CRC, public health officials should promote prevention and management of modifiable risk factors through national policies. The rising incidence and mortality rates of CRC in China may be timely curbed by clarifying specific epidemiological characteristics, optimizing early screening strategies, and strictly implementing diagnosis and treatment guidelines. Thus, this study aimed to collect and report the current research status on epidemiology and risk factors of CRC in China.

Prognosis of synchronous colorectal carcinoma compared to solitary colorectal carcinoma: a matched pair analysis

BACKGROUND

Synchronous colorectal carcinoma (CRC) is a specific and rare type of colorectal malignancy. The data on the impact of synchronous CRC are controversial. This study aimed to compare the characteristics and prognosis between synchronous CRC and solitary CRC.

PATIENTS AND METHODS

252 patients who underwent surgery between October 2009 and June 2013 with synchronous CRC (n = 126) or solitary CRC (n = 126) were included. The patients were matched according to age, sex, American Society of Anesthesiologists score, BMI, cancer grade, tumor location, and tumor stage. The short-term outcomes included the length of hospital stay, complications, and 30-day mortality. Long-term endpoints were overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS).

RESULTS

The median follow-up duration for all patients were 42.5 months. The incidence of synchronous CRC was high than in older and male patients as well as in mucinous adenocarcinoma containing signet-ring cell carcinoma, tumor deposit, and polypus. The length of hospital stay after surgery was longer for synchronous CRC than solitary CRC (median: 10 vs. 4 days, P = 0.033). In multivariate analysis, synchronous CRC was an independent prognostic factor associated with poor OS (hazard ratio: 2.355, 95% confidence interval: 1.322-4.195, P = 0.004), DFS (hazard ratio: 2.079, 95% confidence interval: 1.261-3.429, P = 0.004), and CSS (hazard ratio: 2.429, 95% confidence interval: 1.313-4.493, P = 0.005).

CONCLUSION

The clinical and pathological features exhibit differences between synchronous CRC and solitary CRC and the prognosis of patients with synchronous CRC was poorer than those with solitary CRC.

Relationship between CpG island methylation phenotype, microsatellite instability phenotype and mutation of KRAS, NRAS, and BRAF genes in colorectal cancer

OBJECTIVE

CpG island methylation phenotype (CIMP) and microsatellite instability (MSI) are two different molecular mechanisms in colorectal cancer (CRC). Proto-oncogene KRAS, mutations in NRAS and BRAF play an important role in the formation of colorectal cancer. The correlation between the molecular typing of CIMP and MSI and the genes of KRAS, NRAS and BRAF was explored in this study.

METHODS

A total of 110 paraffin-embedded specimens of colorectal cancer were collected from the Chinese People's Liberation Army Rocket Army Special Medical Center during the period from May 2017 to September 2018. CIMP were detected by DNA methylation quantitative PCR (Methylight). Mutations in KRAS, NRAS, and BRAF genes were detected by realtime fluorescence quantitative PCR (qPCR); MSI typing was detected by sequencing.

RESULTS

Of the 110 colorectal cancer samples, 11 cases (10%) were CIMP-H, 92 cases (83.64%) were CIMP-L, and 7 cases (6.36%) were CIMP-0. 10 cases (9.09%) were MSI-H, and 100 cases (90.91%) were MSS and MSI-L. The mutation rates of KRAS, NRAS and BRAF genes were 50% (55 cases), 6.36% (7 cases) and 5.45% (6 cases), respectively. There was no significant correlation between CIMP group and MSI group (P > 0.05). Also, no significant differences were found in the mutations between the three subtypes of the CIMP group and the KRAS, NRAS genes (P > 0.05), while there was a statistically significant difference among the three subtypes of the BR and the BRAF gene mutations (P < 0.0001). There were no obvious differences between the three states of microsatellites and the mutations of KRAS and NRAS genes (P > 0.05), and the differences between them and BRAF gene mutations were statistically significant (P < 0.01).

CONCLUSIONS

The BRAF gene mutation is closely related to the two types of CIMP and MSI, which may be an important part of the above two molecular mechanisms, and provide a reference for the treatment of the patients with CIMP-H and MSI-H.

Advances in Identification of Susceptibility Gene Defects of Hereditary Colorectal Cancer

Colorectal cancer (CRC) is a common malignant tumor of the digestive system worldwide, associated with hereditary genetic features. CRC with a Mendelian genetic predisposition accounts for approximately 5-10% of total CRC cases, mainly caused by a single germline mutation of a CRC susceptibility gene. The main subtypes of hereditary CRC are hereditary non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP). With the rapid development of genetic testing methods, especially next-generation sequencing technology, multiple genes have now been confirmed to be pathogenic, including DNA repair or DNA mismatch repair genes such as APC, MLH1, and MSH2. Since familial CRC patients have poor clinical outcomes, timely clinical diagnosis and mutation screening of susceptibility genes will aid clinicians in establishing appropriate risk assessment and treatment interventions at a personal level. Here, we systematically summarize the susceptibility genes identified to date and the potential pathogenic mechanism of HNPCC and FAP development. Moreover, clinical recommendations for susceptibility gene screening, diagnosis, and treatment of HNPCC and FAP are discussed.

Endometrial carcinoma-related genetic factors: application to research and clinical practice in China

Genetic factors affect the initiation and progression of endometrial carcinoma (EC). The routine detection of genetic factors involved in EC has not been extensively performed in Chinese clinical practice, however. In this review we summarise EC-related genetic factors, including Lynch syndrome-associated mutations and non-Lynch syndrome-associated genetic predispositions found in Chinese women, and their potential clinical applications. In addition, we propose a clinical testing strategy for patients with EC and their family members. The objective of this review is to advance basic research regarding the genetic factors involved in EC and to improve its clinical implementation in China.

TWEETABLE ABSTRACT

Review summarises Chinese research progression of EC-related genetic factors and proposes innovative screening strategy.

The identification of Lynch syndrome in Congolese colorectal cancer patients

BACKGROUND

We aimed to investigate the prevalence of Lynch syndrome as one of hereditary causes of colorectal cancer (CRC) among young Congolese individuals affected by the CRC, and to define methods for diagnosis in Congo Brazzaville.

METHODS

We conducted a transversal cohort study of 34 patients having a CRC with a family history for a period of eight years. They were selected among 89 CRCs of any type from the Bethesda guidelines criteria combined with pedigrees. Mismatch repair (MMR) genes alterations were researched by immunohistochemistry (IHC).

RESULTS

We identified with the Bethesda criteria a total of 38.2% (34/89) patients having familial CRC with a confidence interval (CI) of 95%=[0.34-0.41]. Only 14.7% (5/34) 95% CI=[0.34-2.32] patients showed MMR immunodeficiency involving firstly MLH1 protein then MSH2 protein. These data account for 5.6% (5/89) 95% CI=[0.15-0.33] of patients affected by Lynch syndrome with an earlier median age of 35 years (range 20 to 47 years).

CONCLUSION

The prevalence of Lynch syndrome found in Brazzaville is comparable to that is found in northern countries. The combined Bethesda guidelines, pedigree and IHC is an accessible and good alternative method for the positive diagnosis of Lynch syndrome in current practice in Congo.

Clinicopathological Characteristics and Prognosis of Colorectal Cancer in Chinese Adolescent Patients

Background:

Colorectal adenocarcinoma rarely occurred in adolescent. Clinical feature and prognosis of this population are not clear until now. In addition, DNA mismatch repair (MMR) status may relate to the early disease occurrence. The present study aimed to perform a retrospective analysis of adolescent patients with colorectal cancer, including clinicopathological characteristics and prognosis.

Methods:

The medical records of 11,503 patients diagnosed as colorectal cancer in Cancer Hospital, Chinese Academy of Medical Sciences from January 1999 to December 2009 were retrospectively reviewed. Finally, 19 patients who were between 10 and 20 years old were selected as the study group. We summarized the clinicopathological characteristics, analyzed the association with prognosis and assessed the expression of MMR protein by immunohistochemical method.

Results:

The most common primary site was the right colon in 7 patients. Ten patients had Stage III colorectal cancer, 5 patients had Stage IV disease. Signet ring cell carcinoma was the most frequent pathological type (7/19). Deficient MMR was identified in 2 patients. The 5-year survival rate and median survival time were 23.2% and 26 months. Distant metastasis was identified as an independent prognostic factor (P = 0.02).

Conclusions:

Colorectal cancer in Chinese adolescents was very rare. The chinese adolecents with colorectal cancer were frequently diagnosed in the right colon, as Stage III/IV disease with signet ring cell carcinoma. The prognosis was relatively poor.