The genetics of hereditary non-polyposis colorectal cancer and non-polypotic colon cancer

Microsatellite Instability Status of Interval Colorectal Cancers in a Korean Population

Background/Aims

A subset of patients may develop colorectal cancer after a colonoscopy that is negative for malignancy. These missed or de novo lesions are referred to as interval cancers. The aim of this study was to determine whether interval colon cancers are more likely to result from the loss of function of mismatch repair genes than sporadic cancers and to demonstrate microsatellite instability (MSI).

Methods

Interval cancer was defined as a cancer that was diagnosed within 5 years of a negative colonoscopy. Among the patients who underwent an operation for colorectal cancer from January 2013 to December 2014, archived cancer specimens were evaluated for MSI by sequencing microsatellite loci.

Results

Of the 286 colon cancers diagnosed during the study period, 25 (8.7%) represented interval cancer. MSI was found in eight of the 25 patients (32%) that presented interval cancers compared with 22 of the 261 patients (8.4%) that presented sporadic cancers (p=0.002). In the multivariable logistic regression model, MSI was associated with interval cancer (OR, 3.91; 95% confidence interval, 1.38 to 11.05).

Conclusions

Interval cancers were approximately four times more likely to show high MSI than sporadic cancers. Our findings indicate that certain interval cancers may occur because of distinct biological features.

Clinical usefulness of microsatellite instability test in Korean young patients with high-risk features associated with adenoma

The aim of this study was to determine the correlation between microsatellite instability (MSI) and young age in patients with advanced colorectal adenomas. We retrospectively analyzed young patients (≤ 40 years of age) with advanced adenomas (n=84) between January 1996 and December 2006. We randomly selected the control group as patients ≥ 50 years of age with advanced adenomas (n=84) during the same time period. Of these patients, the MSI test and MLH1 immunohistochemistry were performed in the available tissue samples from patients with advanced adenomas. The number of patients who had the two tests was 52 in the young group and 49 in the old group. The monomorphic nature of the BAT26 panel for MSI analysis was used without comparison of normal tissue. MSI was detected in three young patients (n=52) and none of the old patients (n=49). There was no statistical difference between the two groups (P=0.243). All three young patients with MSI had a strong family history of colorectal cancer. MSI analysis was not a useful method of screening for HNPCC in young patients with advanced colorectal adenoma, at least in cases without a family history of colorectal cancer.

The role of the in situ local inflammatory response in predicting recurrence and survival in patients with primary operable colorectal cancer

Colorectal cancer progression and survival is dependent on complex interactions between the tumour and the host. The pronounced local inflammatory response in and around the tumour is thought to represent the in situ host anti-tumour immune response. Since early reports, 40 years ago, there has been a continuing interest in establishing the cellular composition of immune cell infiltrates and their relationship with survival in colorectal cancer. In this review, we comprehensively examine the evidence for the local inflammatory cell reaction/in situ immune response in predicting outcome in primary operable colorectal cancer and make recommendations as to how such information may be incorporated into routine clinical assessment. Generally, an increasing number/density of immune cells in and around the tumour is associated with improved outcome in over 100 studies. Whilst the prognostic value of a generalized lymphocytic infiltrate or non-specific peritumoural inflammatory response is strongly related to survival based on 40 different studies, it is also apparent that most individual immune cell types relate to recurrence and cancer specific survival. The evidence is particularly robust for tumour infiltrating T lymphocytes and their subsets (CD3+, CD8+, CD45RO+, FOXP3+) in addition to tumour associated macrophages, dendritic cells and neutrophils. Taken together, the evidence suggests both adaptive and innate anti-tumour immune responses play key roles in determining cancer progression. In order to establish routine clinical utility there is a need to rationalise this prognostic information, published over a 40 years period, into a standardized assessment of tumour inflammatory cell infiltrate. Such standardization may also guide development of novel therapeutic interventions.

A prospective analysis of microsatellite instability as a molecular marker in colorectal cancer

BACKGROUND

Microsatellite instability (MSI) may be a molecular marker of colorectal tumor biology. We sought to evaluate the incidence and significance of MSI in an unselected colorectal cancer population.

METHODS

Colorectal cancer cases from a community health system were prospectively evaluated for MSI and patient outcomes monitored.

RESULTS

Of 240 eligible, 140 underwent testing; 43 (31%) had high-frequency MSI (MSI-H). Those with MSI-H tumors presented with earlier disease stage (P = .014) and lymphocytic infiltration (P < .001). Stage III MSI-H patients trended toward improved disease-free survival (P = .065). MSI-H patients were more likely to have other primary malignancies.

CONCLUSIONS

Prevalence of MSI-H in the general colorectal cancer population is higher than previously reported. MSI testing of colorectal cancers is useful as part of a molecular profile to stratify patients for prognosis, treatment, and further study. Patients with MSI-H tumors are more likely to have other primary malignancies, suggesting a role for heightened screening.