Is MSI-H of value in predicting the development of metachronous colorectal cancer?

Development and validation of MMR prediction model based on simplified clinicopathological features and serum tumour markers

BACKGROUND

Although simplified clinicopathological features and serum tumour markers (STMs) were reported to be associated with the status of mismatch repair (MMR) in colorectal cancer (CRC) patients, their predictive value alone or in combination for MMR status remains unknown.

METHODS

A retrospective analysis of 3274 participants with MMR testing and STMs measurements from two institutions was conducted. The prediction model was developed in the primary cohort that consisted of 1964 participants. Best subset regression was applied to select the most useful predictors from the primary dataset. The performance of the nomogram was evaluated with respect to its calibration, discrimination, and clinical usefulness. External validation was performed in an independent validation cohort of 1310 consecutive CRC patients.

FINDINGS

Among the ten simplified clinicopathological features, seven variables were selected as the best subset of risk factors to develop pathology-based model, including age, tumour diameters, histology, tumour location, perineural invasion, the number of sampled lymph nodes (LNs) and positive LNs. The model showed good calibration and discrimination, with an AUC of 0.756 (95% CI, 0.722 to 0.789) in the primary cohort and 0.754 (95% CI, 0.715 to 0.793) in the validation cohort. After the addition of CEA and CA 72-4, the performance of pathology-based model was significantly improved in in both the primary cohort (AUC: 0.805 (0.774-0.835) vs. 0.756 (0.722-0.789), P < 0.001) and validation cohort (AUC: 0.796 (0.758-0.835) vs. 0.754 (0.715-0.793), P < 0.001). The results of decision curve analysis revealed that using our models to predict the status of MMR would add more benefit than either the detect-all-patients scheme or the detect-none scheme.

INTERPRETATION

The models based on simplified clinicopathological features alone or in combination with STMs can be conveniently used to facilitate the postoperative individualized prediction of MMR status in CRC patients.

The molecular pathogenesis of colorectal cancer and its potential application to colorectal cancer screening

INTRODUCTION

Advances in our understanding of the molecular genetics and epigenetics of colorectal cancer have led to novel insights into the pathogenesis of this common cancer. These advances have revealed that there are molecular subtypes of colon polyps and colon cancer and that these molecular subclasses have unique and discrete clinical and pathological features. Although the molecular characterization of these subgroups of colorectal polyps and cancer is only partially understood at this time, it does appear likely that classifying colon polyps and cancers based on their genomic instability and/or epigenomic instability status will eventually be useful for informing approaches for the prevention and early detection of colon polyps and colorectal cancer.

CONCLUSIONS

In this review, we will discuss our current understanding of the molecular pathogenesis of the polyp to cancer sequence and the potential to use this information to direct screening and prevention programs.

Epidemiology and familial risk of synchronous and metachronous colorectal cancer: a population-based study in Utah

BACKGROUND & AIMS

Patients diagnosed with colorectal cancer (CRC) are at risk for synchronous and metachronous lesions at the time of diagnosis or during follow-up evaluation. We performed a population-based study to evaluate the rate, predictors, and familial risk for synchronous and metachronous CRC in Utah.

METHODS

All newly diagnosed cases of CRC between 1980 and 2010 were obtained from the Utah Cancer Registry and linked to pedigrees from the Utah Population Database.

RESULTS

Of the 18,782 patients diagnosed with CRC, 134 were diagnosed with synchronous CRC (0.71%) and 300 were diagnosed with metachronous CRC (1.60%). The risk for synchronous CRC was significantly higher in men (odds ratio [OR], 1.45; 95% confidence interval [CI], 1.02-2.06) and in patients aged 65 years or older (OR, 1.50; 95% CI, 1.02-2.21). Synchronous CRCs were located more often in the proximal colon (OR, 1.70; 95% CI, 1.20-2.41). First-degree relatives of cases with synchronous (OR, 1.86; 95% CI, 1.37-2.53), metachronous (OR, 2.34; 95% CI, 1.62-3.36), or solitary CRC (OR, 1.75; 95% CI, 1.63-1.88) were at increased risk for developing CRC, compared with relatives of CRC-free individuals. Four percent of first-degree relatives of patients with synchronous or metachronous cancer developed CRC at younger ages than the age recommended for initiating CRC screening (based on familial risk), and therefore would not have been screened.

CONCLUSIONS

Of patients diagnosed with CRC, 2.3% are found to have synchronous lesions or develop metachronous CRC during follow-up evaluation. Relatives of these patients have a greater risk of CRC than those without a family history of CRC. These results highlight the importance of obtaining a thorough family history and adhering strictly to surveillance guidelines during management of high-risk patients.

Histopathological work-up of resection specimens, local excisions and biopsies in colorectal cancer

The pathological examination of material removed from patients with colorectal neoplasia is important. It provides a wide range of information on, for example, the quality and completeness of excision, the stage and biological aggressiveness, the need for further therapy, and response to therapy. Molecular testing adds valuable information on genetic risk and is required before treatment with anti-EGF-r antibodies. This article highlights the value derived from macroscopic inspection of surgical specimens, careful microscopy and excellent reporting according to national guidelines. Increasing use of a number of preoperative therapies and combinations in rectal cancer change the pathological features found and a standardised approach to the diagnosis of complete response is required. It touches upon the issues with frequent changes in TNM staging and the difficulties these changes are causing. The widespread introduction of bowel cancer screening is changing the stage of presentation of colorectal cancer leading to increasing numbers of local excisions and polyp cancers.

Endoscopic surveillance after curative surgery for sporadic colorectal cancer: patient-tailored, tumor-targeted or biology-driven?

OBJECTIVE

Endoscopy has been endorsed and introduced in most surveillance programs following curative surgery for colorectal cancer (CRC), yet little data are available to support its use in terms of patient selection, efficacy and frequency of surveillance.

MATERIAL AND METHODS

A literature search in the English language using the PubMed/Medline database for the MeSH terms "colorectal cancer", "surveillance", and "endoscopy", with focus on sporadic CRC, excluding CRC developed on a hereditary or inflammatory bowel disease background. Focus on results from the past 5 years was applied.

RESULTS

Recent systematic reviews, meta-analyses, randomized trials and prospective studies made the backbone of the article, supported by population-based findings and recent reports on tumor biology. Hard evidence to support a survival benefit from endoscopy alone is lacking. Definitions of "synchronous", "interval", and "metachronous" cancers are not uniform and hampers comparison of studies. The number of metachronous cancers (usually 2-4%) that develop after curative CRC surgery is small, and better patient-tailored surveillance could improve the diagnostic yield. Compliance with endoscopy is low compared to other modalities. Age and socio-demographic factors influence on the surveillance coverage and need to be addressed in any given program. The majority of local recurrences occur within the first 3 years after surgery independent of stage, and microsatellite instable (MSI) tumors appear to be at higher risk.

CONCLUSIONS

Endoscopy in surveillance after curative surgery for CRC is a resource demanding procedure. A tailored approach according to factors associated with an increased risk for metachronous cancer/local recurrence would increase efficiency.

Sensitivity of immunochemical fecal occult blood test to small colorectal adenomas

BACKGROUND

Although the immunochemical fecal occult blood test (FOBT) is reportedly more sensitive to large adenomas or colorectal cancer (CRC) than the guaiac-based FOBT, the sensitivity of the immunochemical FOBT to small adenomas has scarcely been reported. Previous reports have indicated that the guaiac-based FOBT can detect small adenomas only by serendipity.

OBJECTIVES

To investigate the sensitivity of immunochemical FOBT to small adenomas using a large-scale cohort.

METHODS

We analyzed 21,805 consecutively enrolled asymptomatic persons who underwent colonoscopy and immunochemical FOBT.

RESULTS

The sensitivity to adenomas </=9 mm was significantly higher than the false-positive rate as revealed by analysis of all eligible subjects (7.0%vs 4.5%, P < 0.001). In men, the sensitivity was superior to the false-positive rate and increased with age (<50 yr 6.1% and >60 yr 11.3%). On the other hand, the sensitivity in women was not significantly different from the false-positive rate in any generation (5.1%vs 4.7% for all eligible women, P= 0.72).

CONCLUSIONS

Immunochemical FOBT detected a small percentage of small adenomas in men at a rate that is significantly higher than the false-positive rate. Studies comparing the guaiac and immunochemical FOBTs using the end point of CRC-related death are expected.