Distinct gene expression profiles of proximal and distal colorectal cancer: implications for cytotoxic and targeted therapy

The survival outcome differs between left-sided colon and middle/low rectal cancer after colorectal hepatic metastasectomy

INTRODUCTION

The clinical outcomes between left-sided colon cancer and middle/low rectal cancer appear to be different. We aimed to examine the impact of primary tumor location regarding the left-sided colon and middle/low rectum on the overall survival (OS) of colorectal hepatic metastasectomy.

PATIENTS AND METHODS

Patients who underwent colorectal hepatic metastasectomy were retrospectively enrolled. Patients were classified into two groups according to primary tumor location (left-sided colon and middle/low rectum). Categorical variables were compared using the chi-square test or Fisher's exact test, and continuous variables were analyzed using Student'st-test. Survival was analyzed by the KaplanMeier method and log-rank test. The prognostic factors were analyzed by univariate and multivariate analyses using Cox proportional hazards regression models.

RESULTS

Totally, 365 patients were enrolled. Patients with left-sided colon cancer had significantly better OS than those with middle/low rectal cancer (hazard ratio (HR) 0.725, P=0.018), with a median OS of 48 months and 38 months, respectively. In the subgroup analysis of RAS mutations, those with left-sided colon cancer had significantly prolonged OS compared to those with middle/low rectum cancer (HR 0.608, P=0.034), with a median OS of 49 months and 26 months, respectively. This observation was limited to patients with RAS mutations.

CONCLUSION

According to our findings, middle/low rectal cancer had poorer survival outcome, and should not be categorized together with left-sided colon cancer in terms of OS following colorectal hepatic metastasectomy.

Colonic Fluid and Electrolyte Transport 2022: An Update

Colonic epithelial cells are responsible for maintaining a delicate balance between luminal secretion and the absorption of fluids and ions. This review aims to discuss and update the model of colonic electrolyte secretion and absorption via the cystic fibrosis transmembrane regulator (CFTR), epithelial sodium channel (ENaC), Na-K-Cl cotransporters (NKCC1 and 2), Na-H exchangers (NHE1–4), colonic H,KATPase, and several other key components involved in multi-level transepithelial ion transport. Developments in our understanding of the activity, regulation, localization, and relationships of these ion transporters and their interactions have helped forge a more robust understanding of colonic ion movement that accounts for the colonic epithelium’s role in mucosal pH modulation, the setting of osmotic gradients pivotal for fluid retention and secretion, and cell death regulation. Deviations from homeostatic ion transport cause diarrhea, constipation, and epithelial cell death and contribute to cystic fibrosis, irritable bowel syndrome (IBS), ulcerative colitis, and cancer pathologies. Signal transduction pathways that regulate electrolyte movement and the regulatory relationships between various sensors and transporters (CFTR as a target of CaSR regulation and as a regulator of ENaC and DRA, for example) are imperative aspects of a dynamic and comprehensive model of colonic ion homeostasis.

Prognostic value of the combination of primary tumor location and RAS mutational status on patients with colorectal liver metastasis undergoing hepatectomy

OBJECTIVE

To assess prognostic influences of RAS mutational status and primary tumor site on cases with colorectal liver metastasis (CRLM) who underwent hepatectomy.

METHODS

Clinicopathological data of 762 patients with CRLM who underwent hepatectomy between January 2000 and November 2018 were retrospectively analyzed. The left-sided tumors (LST) included tumors located in the splenic flexure, descending colon, sigmoid colon, and rectum; while right-sided tumors (RST) included those located in the cecum, ascending colon, and transverse colon. RAS mutational status was determined using Sanger sequencing or next-generation sequencing, including KRAS (Codons 12, 13, and 61) and NRAS (Codons 12, 13, and 61), which were defined as wild-type (RASwt) and mutant-type (RASmut), respectively. Survival curves were plotted using the Kaplan-Meier plotter and compared by the log rank test. The clinicopathological data were analyzed using univariate and multivariate analyses.

RESULTS

The 5-year overall survival (OS) in the LST group was longer than that in the RST group (OS: 47.1% vs. 31.0%, p = 0.000, respectively), and the OS in the RASwt group was longer compared with that in the RASmut group (OS: 53.6% vs. 24.0%, p = 0.000). Besides, overall survival of the patients after hepatectomy was alternative, which was stratified by primary tumor site, with the 1-, 3-, and 5-year survival rates of 93.1%, 62.1%, and 47.1% for patients with LST, and 91.1%, 42.8%, and 31.0% for patients with RST, respectively. OS and disease-free survival (DFS) were significantly different stratified by RAS mutational status, with the 1-, 3-, and 5-year rates of 96.9%, 67.9%, and 53.6% for patients with RASwt tumors, and 85.7%, 41.5%, and 24.0% for patients with RASmut tumors, respectively. The 1-, 3-, and 5-year DFS rates were 51.9%, 30.0%, and 26.7% for patients with RASwt tumors, and 35.8%, 18.2%, and 14.9% for patients with RASmut tumors, respectively. The results of multivariate analysis showed that RAS mutational status and primary tumor site were both independent influencing factors of OS.

CONCLUSION

RAS mutational status and primary tumor site affect OS independently in CRLM patients undergoing hepatectomy. The worse prognosis of RST cannot be simply attributed to the imbalance of RAS mutational status in different primary tumor sites.

SPARCL1 exhibits different expressions in left- and right-sided colon cancer and is downregulated via DNA methylation

Aim: The authors previously found that SPARCL1 functions to suppress colorectal cancer metastasis. Here, the epigenetic mechanism of SPARCL1 regulation and its relationship with clinicopathological features in colon cancer were investigated. Materials & methods: SPARCL1 expression was evaluated by immunohistochemistry staining in a tissue array containing 271 left-sided colon cancer samples and 257 right-sided colon cancer samples. In vivo and in vitro DNA methylation states were measured by biochemical sulfide potential assay. The transcription and DNA methylation states in cells were altered by siRNA or decitabine treatment, respectively. Cellular motility properties were compared through transwell assay. Results & conclusion: SPARCL1, mediated by its DNA methylation, may arrest colorectal carcinoma motility. Furthermore, SPARCL1 expression is higher and may have a specific prognostic value in left-sided colon cancer.

Ethanol exposure drives colon location specific cell composition changes in a normal colon crypt 3D organoid model

Alcohol is a consistently identified risk factor for colon cancer. However, the molecular mechanism underlying its effect on normal colon crypt cells remains poorly understood. We employed RNA-sequencing to asses transcriptomic response to ethanol exposure (0.2% vol:vol) in 3D organoid lines derived from healthy colon (n = 34). Paired regression analysis identified 2,162 differentially expressed genes in response to ethanol. When stratified by colon location, a far greater number of differentially expressed genes were identified in organoids derived from the left versus right colon, many of which corresponded to cell-type specific markers. To test the hypothesis that the effects of ethanol treatment on colon organoid populations were in part due to differential cell composition, we incorporated external single cell RNA-sequencing data from normal colon biopsies to estimate cellular proportions following single cell deconvolution. We inferred cell-type-specific changes, and observed an increase in transit amplifying cells following ethanol exposure that was greater in organoids from the left than right colon, with a concomitant decrease in more differentiated cells. If this occurs in the colon following alcohol consumption, this would lead to an increased zone of cells in the lower crypt where conditions are optimal for cell division and the potential to develop mutations.

Demographics Predict Stage III/IV Colorectal Cancer in Individuals Under Age 50

GOALS

The goal of this study was to quantify the association between demographic factors and advanced colorectal cancer (CRC) in patients under age 50.

BACKGROUND

CRC incidence in the United States has declined in older individuals but increased in those under age 50 (early-onset). More than 60% of early-onset CRC patients present with advanced disease (stage III/IV), but predictors of stage in this population are poorly defined.

STUDY

We analyzed CRC cases diagnosed between age 20 and 49 in the United States Surveillance, Epidemiology, and End Results (SEER) 18 database during 2004 to 2015. Logistic regression models were fit to assess the impact of age, sex, race, ethnicity, marital status, and cancer site on the probability of advanced disease.

RESULTS

The analysis included 37,044 cases. On multivariable regression, age was inversely associated with advanced disease. Relative to 45 to 49-year-olds, 40 to 44-year-olds had 8% greater odds of having advanced CRC, and 20 to 24-year-olds had 53% greater odds. Asians, blacks, and Pacific Islanders had 10%, 12%, and 45% greater odds of advanced disease compared with whites. Compared with nonpartnered individuals, those with partners had 11% lower odds of advanced CRC. Both right-sided and left-sided colon cancer were more likely to be diagnosed at stage IV compared with rectal cancer.

CONCLUSIONS

Among individuals with early-onset CRC, younger age, Asian, black, or Pacific Islander race, and being nonpartnered were predictors of advanced disease at presentation. Colon cancer was more likely to be diagnosed at stage IV than rectal cancer. Patient characteristics associated with advanced CRC may indicate both differences in tumor biology and disparities in health care access.

Primary tumor location and survival in colorectal cancer: A retrospective cohort study

BACKGROUND

Primary tumor location is a prognostic factor for metastatic colorectal cancer (mCRC). Post hoc analyses of mCRC clinical trials, including FIRE-3, CALGB/SWOG 80405, suggest that primary tumor location is also predictive of survival benefit with cetuximab or bevacizumab in combination with 5-fluorouracil-based chemotherapy.

AIM

Evaluate prognostic/predictive roles of primary tumor location in real-world mCRC patients treated with cetuximab or bevacizumab plus 5-fluorouracil-based chemotherapy.

METHODS

This retrospective cohort study selected patients with KRAS wild-type mCRC who initiated first-line therapy with cetuximab or bevacizumab in combination with 5-fluorouracil/leucovorin/irinotecan (FOLFIRI) or 5-fluorouracil/ leucovorin/oxaliplatin (FOLFOX) between January 2013 and April 2017 from the Flatiron Health electronic health record-derived database of de-identified patient-level data in the United States. Primary tumor location was abstracted from patients’ charts. Left-sided primary tumor location (LPTL) was defined as tumors that originated in the splenic flexure, descending colon, sigmoid colon, or rectum; right-sided primary tumor location (RPTL) was defined as tumors that originated from the appendix, cecum, ascending colon, hepatic flexure, or transverse colon. Propensity score matching was used to balance the baseline demographic and clinical characteristics between patients treated with cetuximab and patients treated with bevacizumab. Kaplan-Meier and Cox regression methods were used for survival analyses.

RESULTS

A total of 1312 patients met the selection criteria. Of 248 cetuximab plus FOLFIRI or FOLFOX patients, 164 had LPTL and 84 had RPTL; of 1064 bevacizumab plus FOLFIRI or FOLFOX patients, 679 had LPTL and 385 had RPTL. Cetuximab LPTL and RPTL patients were more likely to receive FOLFIRI vs bevacizumab patients (LPTL: 64.0% vs 24.3%; RPTL: 76.2% vs 24.9%, P < 0.001). Stage at initial diagnosis was different between cetuximab RPTL vs bevacizumab RPTL patients (P < 0.001); cetuximab RPTL patients were more likely to have stage III disease (44.0% vs 22.6%), while bevacizumab RPTL patients were more likely to have stage IV disease (65.7% vs 48.8%). Cetuximab RPTL patients were more likely to have a documented history of adjuvant chemotherapy vs bevacizumab RPTL patients (47.6% vs 22.3%, P < 0.001). In the propensity score-matched sample, median overall survival (OS) was 29.7 mo (95%CI: 26.9-35.2) for LPTL patients vs 18.3 mo (95%CI: 15.8-21.3) for RPTL patients (P < 0.001). Median OS was 29.7 mo (95%CI: 27.4-NA) for cetuximab LPTL patients vs 29.1 mo (95%CI: 26.6-35.6) for bevacizumab LPTL patients (HR = 0.87; 95%CI: 0.63-1.19; P = 0.378) and 17.0 mo (95%CI: 12.0-32.6) for cetuximab RPTL patients vs 18.8 mo (95%CI: 15.8-22.3) for bevacizumab RPTL patients (HR = 1.00; 95%CI: 0.68-1.46; P = 0.996). The interaction of treatment and primary tumor location was not significant in the Cox regression.

CONCLUSION

In this real-world mCRC cohort, the prognostic role of primary tumor location was substantiated, but not the predictive role for treatment with cetuximab vs bevacizumab in combination with 5-fluorouracil-based chemotherapy.

Expression and Malignant Potential of B4GALNT4 in Esophageal Squamous Cell Carcinoma

BACKGROUND

β-1,4-N-Acetyl-galactosaminyltransferase 4 (B4GALNT4), an enzyme involved in ganglioside synthesis, is upregulated in many cancers. We examine B4GALNT4 expression and its relationship to prognosis in esophageal squamous cell carcinoma (ESCC).

PATIENTS AND METHODS

Expression of B4GALNT4 mRNA and B4GALNT4 protein was analyzed by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and immunohistochemistry, respectively, in 17 human ESCC cell lines and/or clinical specimens from two independent cohorts of 147 and 159 ESCC patients. The contributions of B4GALNT4 to proliferation, invasion, migration, and adhesion was evaluated in ESCC cells subjected to siRNA-mediated gene knockdown. Correlations between clinicopathological parameters and B4GALNT4 expression in clinical specimens were analyzed in both patient cohorts.

RESULTS

B4GALNT4 mRNA expression levels varied widely in ESCC cell lines, regardless of differentiation status or the originating tissue. Knockdown of B4GALNT4 significantly suppressed the proliferation, invasion, migration, and adhesion of ESCC cell lines compared with control cells. B4GALNT4 mRNA was overexpressed in ESCC tissues compared with adjacent normal esophageal tissues. High mRNA expression was significantly associated with poor disease-free survival and hematogenous recurrence, and high B4GALNT4 protein expression was also significantly related to poor disease-specific survival. On multivariable analysis, high B4GALNT4 expression was an independent predictor of poor prognosis. In both patient cohorts, high B4GALNT4 expression did not correlate with known prognostic factors, such as disease stage, lymphovascular invasion, or squamous cell-carcinoma-related antigen level.

CONCLUSIONS

B4GALNT4 influences the malignant behavior of ESCC cells. B4GALNT4 expression may serve as a novel prognostic marker, independent of established risk factors, for ESCC patients.

PIK3CA mutation and clinicopathological features of colorectal cancer: a systematic review and Meta-Analysis

Background: There is conflicting evidence regarding the association between PIK3CA mutations and clinicopathological features of colorectal cancer (CRC). We performed a comprehensive meta-analysis investigating the association between PIK3CA mutations and clinicopathological features in CRC, including subgroup analysis of mutations in exons 9 and 20, to elucidate the role of PIK3CA mutations in CRC.Materials and Methods: A detailed literature search was performed within the PubMed, Web of Science, and Embase databases, examining the associations between PIK3CA mutations and demographic characteristics, clinicopathologic parameters, and molecular features in patients with CRC. The odds ratios with 95% confidence intervals were used to estimate the effect of PIK3CA mutations on outcome parameters.Results: Forty-four studies enrolling 17621 patients were eligible for inclusion. PIK3CA mutations were associated with proximal tumor location, mucinous differentiation, KRAS mutations, and microsatellite instability (MSI). Subgroup analysis demonstrated that PIK3CA exon 9 mutations were positively associated with proximal tumor location and KRAS mutations, and negatively associated with BRAF mutations and MSI; exon 20 mutations were associated with proximal tumor location, KRAS mutations, BRAF mutations and MSI.Conclusions: Our findings suggest that overall or exon-specific PIK3CA mutations showed null associations with key clinicopathological parameters, including disease stage and tumor differentiation, indicating that PIK3CA mutations do not predict aggressive clinicopathological characteristics in CRC. As PIK3CA mutations were found to be closely associated with KRAS mutations, their relationship warrants further investigation. Since PIK3CA exon 9 and 20 mutations showed different tendencies with regard to BRAF mutation and MSI status, they may have distinct molecular impacts on CRC.

Tumour location and efficacy of first-line EGFR inhibitors in KRAS/RAS wild-type metastatic colorectal cancer: retrospective analyses of two phase II randomised Spanish TTD trials

Purpose

Metastatic colorectal cancer (mCRC) is a group of distinct diseases, with clinical and molecular differences between right-sided and left-sided tumours driving varying prognosis.

Methods

Patients with KRAS/RAS-wild type (wt) mCRC treated in first line with epidermal growth factor receptor inhibitors (EGFR-Is) (cetuximab or panitumumab) plus oxaliplatin or irinotecan-based chemotherapy from two phase II randomised trials conducted by the Spanish Cooperative for the Treatment of Digestive Tumours group were included in this retrospective study. The main objective was to analyse the prognostic effect of primary tumour location on objective response rate (ORR), progression-free survival (PFS) and overall survival (OS).

Results

Patients with KRAS-wt right-sided tumours (n=52) had significantly lower efficacy as compared with patients with KRAS-wt left-sided tumours (n=209); confirmed ORR (25% vs 47%, respectively; OR 0.4, 95% CI 0.2 to 0.8, p=0.004); and shorter median PFS (7.2 vs 9.9 months; HR 0.6, 95% CI 0.4 to 0.9, p=0.0157) and OS (13.6 vs 27.7 months; HR 0.5, 95% CI 0.3 to 0.7, p<0.0001). Similar results were observed in the RAS-wt populations. The further classification of left-sided tumours as colon or rectum delivered similar survival outcomes, as well as a tendency to diminished ORR in patients with rectum tumours.

Conclusion

We observed significantly improved efficacy outcomes in patients with KRAS/RAS-wt mCRC treated with first-line EGFR-I plus chemotherapy in left-sided primary tumours as compared with right-sided primary tumours.

Trial registration numbers

NCT01161316 and NCT00885885.

Gut butyrate-producing organisms correlate to Placenta Specific 8 protein: Importance to colorectal cancer progression

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Genes from stools have molecular significance with CRC tumorgenesis.

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SCFAs, the metabolites of microbiota, can suppress CRC tumorigenesis.

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Relationship between colonic genes, gut microbiota, or their metabolites is significant.

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Changes of PLAC8 and butyrate-producing organisms were found in stools of CRC patients.

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Butyrate can reduce the CRC formation through regulating PLAC8 expression.

Tumor metastasis or recurrence often occurs in patients with curative resection of colorectal cancer (CRC). Placental-specific 8 (PLAC8), which has increased expression in stool, may be associated with CRC recurrence. Insights into the role of PLAC8 in CRC recurrence and its clinical significance may support to develop strategies for preventing CRC recurrence and deterioration. Clinical tissues, cell and animal models were used to clarify the roles of PLAC8 in CRC tumorigenesis, invasion, and migration. Next-generation sequencing of 16S ribosomal DNA has been used to assess the gut microbiota in stool of CRC patients. We found that PLAC8 was upregulated in tissues from patients with late-stage CRC. In our in vitro studies, PLAC8 was dynamically regulated in mitotic cells. Overexpressed PLAC8 was nucleated at the centrosome during mitosis, and therefore, PLAC8 overexpression might increase cell growth and migration (all p < 0.05). The tumorigenic and invasive effects of PLAC8 on CRC cells were also confirmed in a xenograft mouse model. We further identified reduced levels of two butyrate-producing organisms, Butyricicoccus and Prevotella spp., in stools from CRC patients. We found that butyrate downregulated PLAC8 expression and induced apoptosis in PLAC8-overexpressing cells. Our data suggests that PLAC8 gene and protein expression and dysbiosis of gut microflora, especially in butyrate-producing microorganisms, may be indicators of CRC progression.

First Biologic Drug in the Treatment of RAS Wild-Type Metastatic Colorectal Cancer: Anti-EGFR or Bevacizumab? Results From a Meta-Analysis

Introduction: We performed a meta-analysis in order to analyze and quantify the effect on survival of starting therapy in RAS wild-type (wt) metastatic colorectal cancer (mCRC) patients with anti-EGFR agents or bevacizumab.

Patients and Methods: Randomized, phase II or III, clinical trials reporting overall survival (OS) in RAS wt mCRC patients treated with first-line chemotherapy (CT) associated with bevacizumab or anti-EGFR agents were selected. The primary end-point of this meta-analysis was OS; findings were depicted in classical Forest plots.

Results: Seven studies met the criteria for meta-analysis including 3,805 patients. The pooled second-line cross-over rate to bevacizumab was 36.6%, to anti-EGFR 33.2%. Only one study was selected reporting comparison between CT vs. CT plus bevacizumab in RAS wt patients with a HR of 1.13 in favor of CT (CI: 0.89–1.43, p = 0.317). The pooled HRs were 0.89 (95% CI: 0.79–1.00) for CT plus anti-EGFR vs. CT and 0.81 (95% CI: 0.71–0.92) in favor of CT plus anti-EGFR vs. CT plus bevacizumab. Subgroup analysis showed a positive prognostic impact of starting CT plus anti-EGFR in left colon cancer (pooled HR: 0.70; CI: 0.54–0.85) while a positive trend of starting CT plus bevacizumab was observed in right colon cancer (pooled HR: 1.29; CI: 0.81–1.77).

Conclusions: This meta-analysis shows that starting therapy in RAS wt mCRC patients with an anti-EGFR agent improves OS when the primary tumor location is in the left colon but a strong limitation of previous studies is the very low rate of biologic drug therapy cross-over.

The impact of primary tumour location in patients undergoing hepatic resection for colorectal liver metastasis

BACKGROUND

Primary tumour location has long been debated as a prognostic factor in colorectal cancer patients with liver metastases (CRLM) undergoing liver resection. This retrospective study was conducted to clarify the prognostic value of tumour location after radical hepatectomy for CRLM and its underlying causes.

METHODS

We retrospectively analysed clinical data from 420 patients with CRLM whom underwent liver resection between January 2002 and December 2015. Right-sided (RS) tumours include tumours located in the cecum, ascending colon, and transverse colon, and left-sided (LS) tumours include those located in the splenic flexure, descending colon, sigmoid colon, and rectum.

RESULTS

Both overall survival (OS) and disease-free survival (DFS) were similar between patients with RS and LS primary tumours (5-year OS: 46.5% vs 38.3%, P = 0.699; 5-year DFS: 29.1% vs 22.4%, P = 0.536). Specifically, RAS mutation rate was significantly higher in patients with RS tumours (P = 0.007). Subgroup analysis showed that the RAS mutation on the LS and RS tumours have different prognostic impact for CRLM patients on long-term survival after hepatic resection (RS, OS: P = 0.437, DFS: P = 0.471; LS, OS: P < 0.001, DFS: P = 0.002). The multivariable analysis showed that RAS mutant is an independent factor influencing OS in patients with LS primary tumour only.

CONCLUSIONS

The site of the primary tumour has no significant impact on the long-term survival in patients with CRLM undergoing radical surgery. However, prognostic value of RAS status differs depending on the site of the primary tumour.

Proteome Heterogeneity in Colorectal Cancer

Tumor heterogeneity is an important feature of colorectal cancer (CRC) manifested by dynamic changes in gene expression, protein expression, and availability of different tumor subtypes. Recent publications in the past 10 years have revealed proteome heterogeneity between different colorectal tumors and within the same tumor site. This paper reviews recent research works on the proteome heterogeneity in CRC, which includes the heterogeneity within a single tumor (intratumor heterogeneity), between different anatomical sites at the same organ, and between primary and metastatic sites (intertumor heterogeneity). The potential use of proteome heterogeneity in precision medicine and its implications in biomarker discovery and therapeutic outcomes will be discussed. Identification of the unique proteome landscape between and within individual tumors is imperative for understanding cancer biology and the management of CRC patients.

EGFR expression in patients with stage III colorectal cancer after adjuvant chemotherapy and on cancer cell function

The epidermal growth factor receptor (EGFR)/RAS/RAF/MEK/MAPK pathway plays a crucial role in the carcinogenesis, invasion and metastasis of colorectal cancer (CRC). However, its role in the prognosis and prediction of relapse in patients with stage III CRC after adjuvant chemotherapy remains controversial. In the present study, the clinicopathological features of 173 patients with stage III CRC who underwent radical resection and adjuvant chemotherapy with the fluoropyrimidine/folinic acid, and oxaliplatin (FOLFOX) regimen, and their prognostic values of EGFR expression were retrospectively analyzed. By conducting an in vitro CRC cell line study through the knockdown of EGFR expression, we analyzed cell proliferation, colony formation and migration. Positive EGFR expression and an abnormal postoperative serum carcinoembryonic antigen (CEA) level were found to be significant independent negative predictive factors for postoperative relapse. Furthermore, positive EGFR expression was a significant independent negative prognostic factor for disease-free survival (DFS) and overall survival (OS). Additionally, an in vitro cell line study showed that the knockdown of EGFR expression significantly reduced CRC cell proliferation, colony formation and migration. The results of in vitro and in vivo experiments demonstrated that EGFR expression had a prognostic value for OS and DFS, as well as predictive roles for postoperative relapse, in patients with stage III CRC. By analyzing both EGFR expression and the postoperative CEA, the patients with stage III CRC who were at a high risk of postoperative relapse, or mortality following adjuvant chemotherapy could be identified. In short, CRC cells with EGFR expression would exhibit a highly malignant behavior.

The predictive value of primary tumor location in patients with metastatic colorectal cancer: A systematic review

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. It has been reported that left- and right-sided CRC harbor varying disease characteristics, which leads to a difference in prognosis and response to therapy. Recently, there have been retrospective studies about tumor location in metastatic CRC (mCRC) and its potential to predict the effect of anti-vascular endothelial growth factor and anti-epidermal growth factor receptor (anti-EGFR) therapies. In this review, we provide a comprehensive overview of the latest trials studying the predictive value of primary tumor location in mCRC and discuss biomarkers that might be associated with the differences in treatment response. Although data need to be interpreted with caution due to the absence of randomized trials stratified based on tumor location, patients with left-sided CRC seem to benefit more from anti-EGFR therapy than patients with right-sided CRC. Further clinical trials, stratified for tumor location, are warranted.

Molecular Profiling of Patients With Advanced Colorectal Cancer: Princess Margaret Cancer Centre Experience

BACKGROUND

Molecular aberrations in KRAS, NRAS, BRAF, and PIK3CA have been well-described in advanced colorectal cancer. The incidences of other mutations are less known. We report results of molecular profiling of advanced colorectal cancer in an academic cancer center.

PATIENTS AND METHODS

Patients with advanced colorectal were enrolled in an institution-wide molecular profiling program. Profiling was performed on formalin-fixed paraffin embedded archival tissues using a customized MassArray panel (23 genes, 279 mutations) or the Illumina MiSeq TruSeq Cancer Panel (48 genes, 212 amplicons, ≥ 500× coverage) in a Clinical Laboratory Improvement Amendments-certified laboratory. PTEN was determined by immunohistochemistry.

RESULTS

From March 2012 to April 2014, 245 patients were enrolled. At least one mutation was found in 54% (97/178) and 91% (61/67) of patients using MassArray or MiSeq platforms, respectively (P < .01). Of all patients, KRAS G12/13 mutation was identified in 39%, and non-G12/13 KRAS, BRAF, or NRAS mutations were present in 9%, 6%, and 4%, respectively. Other common mutations included TP53 (68.7%), APC (41.8%), and PIK3CA (13.5%). Co-mutation with KRAS, NRAS, or BRAF was found in 75% of patients with PIK3CA mutation. Of 106 patients with known PTEN immunohistochemistry status, 16% were negative. A higher average number of mutations were observed in right versus left colorectal cancer (P < .01), with 13 of 14 BRAF mutations located in right colon cancer.

CONCLUSION

Mutations are common in advanced colorectal cancer. Right colon cancers harbor more genetic aberrations than left colon or rectal cancers. These aberrations may contribute to differential outcomes to anti-epidermal growth factor receptor therapy among patients with right colon, left colon, or rectal cancers.

Integrating TYMS, KRAS and BRAF testing in patients with metastatic colorectal cancer

AIM

To investigate the impact of thymidylate synthase (TYMS), KRAS and BRAF in the survival of metastatic colorectal cancer (mCRC) patients treated with chemotherapy.

METHODS

Clinical data were collected retrospectively from records of consecutive patients with mCRC treated with fluoropyrimidine-based chemotherapy from 1/2005 to 1/2007. Formalin-fixed paraffin-embedded tissues were retrieved for analysis. TYMS genotypes were identified with restriction fragment analysis PCR, while KRAS and BRAF mutation status was evaluated using real-time PCR assays. TYMS gene polymorphisms of each of the 3’ untranslated region (UTR) and 5’UTR were classified into three groups according to the probability they have for high, medium and low TYMS expression (and similar levels of risk) based on evidence from previous studies. Univariate and multivariate survival analyses were performed.

RESULTS

The analysis recovered 89 patients with mCRC (46.1% de novo metastatic disease and 53.9% relapsed). Of these, 46 patients (51.7%) had colon cancer and 43 (48.3%) rectal cancer as primary. All patients were treated with fluoropyrimidine-based chemotherapy (5FU or capecitabine) as single-agent or in combination with irinotecan or/and oxaliplatin or/and bevacizumab. With a median follow-up time of 14.8 mo (range 0-119.8), 85 patients (95.5%) experienced disease progression, and 63 deaths (70.8%) were recorded. The 3-year and 5-year OS rate was 25.4% and 7.7% while the 3-year progression-free survival rate was 7.1%. Multivariate analysis of TYMS polymorphisms, KRAS and BRAF with clinicopathological parameters indicated that TYMS 3’UTR polymorphisms are associated with risk for disease progression and death (P < 0.05 and P < 0.03 respectively). When compared to tumors without any del allele (genotypes ins/ins and ins/loss of heterozygosity (LOH) linked with high TYMS expression) tumors with del/del genotype (low expression group) and tumors with ins/del or del/LOH (intermediate expression group) have lower risk for disease progression (HR = 0.432, 95%CI: 0.198-0.946, P < 0.04 and HR = 0.513, 95%CI: 0.287-0.919, P < 0.03 respectively) and death (HR = 0.366, 95%CI: 0.162-0.827, P < 0.02 and HR = 0.559, 95%CI: 0.309-1.113, P < 0.06 respectively). Additionally, KRAS mutation was associated independently with the risk of disease progression (HR = 1.600, 95%CI: 1.011-2.531, P < 0.05). The addition of irinotecan in 1^st line chemotherapy was associated independently with lower risk for disease progression and death (HR = 0.600, 95%CI: 0.372-0.969, P < 0.04 and HR = 0.352, 95%CI: 0.164-0.757, P < 0.01 respectively).

CONCLUSION

The TYMS genotypes ins/ins and ins/LOH associate with worst prognosis in mCRC patients under fluoropyrimidine-based chemotherapy. Large prospective studies are needed for validation of our findings.

Tandem repeat variation near the HIC1 (hypermethylated in cancer 1) promoter predicts outcome of oxaliplatin-based chemotherapy in patients with metastatic colorectal cancer

BACKGROUND

The hypermethylated in cancer 1/sirtuin 1 (HIC1/SIRT1) axis plays an important role in regulating the nucleotide excision repair pathway, which is the main oxaliplatin-induced damage-repair system. On the basis of prior evidence that the variable number of tandem repeat (VNTR) sequence located near the promoter lesion of HIC1 is associated with HIC1 gene expression, the authors tested the hypothesis that this VNTR is associated with clinical outcome in patients with metastatic colorectal cancer who receive oxaliplatin-based chemotherapy.

METHODS

Four independent cohorts were tested. Patients who received oxaliplatin-based chemotherapy served as the training cohort (n = 218), and those who received treatment without oxaliplatin served as the control cohort (n = 215). Two cohorts of patients who received oxaliplatin-based chemotherapy were used for validation studies (n = 176 and n = 73). The VNTR sequence near HIC1 was analyzed by polymerase chain reaction analysis and gel electrophoresis and was tested for associations with the response rate, progression-free survival, and overall survival.

RESULTS

In the training cohort, patients who harbored at least 5 tandem repeats (TRs) in both alleles had a significantly shorter PFS compared with those who had fewer than 4 TRs in at least 1 allele (9.5 vs 11.6 months; hazard ratio, 1.93; P = .012), and these findings remained statistically significant after multivariate analysis (hazard ratio, 2.00; 95% confidence interval, 1.13-3.54; P = .018). This preliminary association was confirmed in the validation cohort, and patients who had at least 5 TRs in both alleles had a worse PFS compared with the other cohort (7.9 vs 9.8 months; hazard ratio, 1.85; P = .044).

CONCLUSIONS

The current findings suggest that the VNTR sequence near HIC1 could be a predictive marker for oxaliplatin-based chemotherapy in patients with metastatic colorectal cancer. Cancer 2017;123:4506-14. © 2017 American Cancer Society.

Current and future biomarkers in the treatment of colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer deaths worldwide. CRC develops as a consequence of genomic instability, characterized by various genetic and epigenetic alterations. Its molecular heterogeneity explains the large variability in patient prognosis and treatment response, emphasizing the need for development of accurate prognostic and predictive biomarkers. This article delineates the different pathways of colorectal carcinogenesis and its molecular subtype classification. With this review, we aim to provide a comprehensive overview of the current and future biomarkers guiding clinical decision-making and CRC treatment.

Survival and Prognostic Factors for Metachronous Peritoneal Metastasis in Patients with Colon Cancer

BACKGROUND

The clinical course of metachronous peritoneal metastasis of colorectal origin is poorly understood. In this retrospective study, we aimed to elucidate survival and prognostic factors for metachronous peritoneal metastasis.

METHODS

Patients with metachronous peritoneal metastasis after curative resection for stage I-III colon cancer were retrospectively reviewed, and the incidence and prognosis of metachronous peritoneal metastasis were investigated. Prognostic factors were identified by univariate and multivariate analyses.

RESULTS

Among 1582 surgically resected stage I-III colon cancer patients, 65 developed metachronous peritoneal metastasis. The 5-year cumulative incidence rate was 4.5%, and the median survival after diagnosis of peritoneal metastasis was 29.6 months. None of the patients underwent peritonectomy or intraperitoneal chemotherapy. Independent prognostic factors included right colon cancer [hazard ratio (HR) 2.69, 95% confidence interval (CI) 1.26-5.64; p = 0.011], time to metachronous peritoneal metastasis of <1 year (HR 2.02, 95% CI 1.04-3.87; p = 0.040), Peritoneal Cancer Index (PCI) >10 (HR 3.68, 95% CI 1.37-8.99; p = 0.012), concurrent metastases (HR 4.09, 95% CI 2.02-8.23; p < 0.001), and peritoneal nodule resection (HR 0.31, 95% CI 0.13-0.65; p = 0.002).

CONCLUSIONS

A proportion of colon cancer patients with metachronous peritoneal metastasis may benefit from combined peritoneal nodule resection and systemic chemotherapy. Right colon cancer, early peritoneal metastasis, a high PCI, and concurrent metastases negatively affected prognosis in patients with metachronous peritoneal metastasis.

Differential Radiographic Appearance of BRAF V600E-Mutant Metastatic Colorectal Cancer in Patients Matched by Primary Tumor Location

BACKGROUND

BRAF-mutant metastatic colorectal cancers (mCRCs) share many clinicopathologic features with right-sided colon tumors, including frequent peritoneal involvement. Because of the poorer outcomes associated with BRAF mutations, early enrollment in clinical trials has been encouraged. However, the use of standard eligibility and assessment criteria, such as measurable disease, has anecdotally impeded patient accrual and restricted appraisal of treatment response. We investigated whether the presence of a BRAF V600E mutation is differentially associated with sites and appearance of metastatic disease in patients matched by primary tumor location.

METHODS

A total of 40 patients with BRAF-mutant mCRC were matched to 80 patients with BRAF wild-type mCRC by location of primary tumor (right or left colon; rectum), sex, and age. Associations between BRAF mutation status and clinicopathologic characteristics and metastatic sites were analyzed using proportion tests. Survival was summarized with Kaplan-Meier and Cox regression methods.

RESULTS

The distribution of primary tumor locations was: 60% right colon, 30% left colon, and 10% rectum. Compared with BRAF wild-type tumors, BRAF-mutant tumors more commonly associated with peritoneal metastases (50% vs 31%; P=.045) and ascites (50% vs 24%; P=.0038). In patients with left colon primaries, BRAF mutations were associated with more frequent ascites (58% vs 12%; P=.0038) and less frequent liver metastases (42% vs 79%; P=.024). Among patients with right colon primaries, no significant difference in sites of disease by BRAF mutation status was observed. Disease was not measurable by RECIST 1.1 in 24% of patients with right-sided primary tumors, irrespective of BRAF mutation status. In the BRAF-mutated cohort, ascites correlated unfavorably with survival (hazard ratio, 2.35; 95% CI, 1.14, 4.83; P=.02).

CONCLUSIONS

Greater frequency of ascites and peritoneal metastases, which pose challenges for RECIST 1.1 interpretation of therapeutic outcomes, are seen with BRAF-mutant mCRC, even when patients are matched for primary tumor location.

Prognostic Impact of Primary Tumor Location on Clinical Outcomes of Metastatic Colorectal Cancer Treated With Cetuximab Plus Oxaliplatin-Based Chemotherapy: A Subgroup Analysis of the JACCRO CC-05/06 Trials

INTRODUCTION

Primary tumor location is a critical prognostic factor in metastatic colorectal cancer (mCRC); however, it remains unclear whether tumor location is a predictor of the response to cetuximab treatment. It is also uncertain if BRAF mutation contributes to the impact of tumor location on survival. We assessed the prognostic impact of tumor location on clinical outcomes in mCRC patients treated with first-line cetuximab chemotherapy.

PATIENTS AND METHODS

The associations of tumor location with overall survival and progression-free survival were evaluated in mCRC patients with KRAS exon 2 wild-type tumors who were enrolled onto 2 clinical trials: JACCRO CC-05 of cetuximab plus FOLFOX (n = 57, UMIN000004197) and CC-06 of cetuximab plus SOX (n = 61, UMIN000007022). Tumors proximal or from splenic flexure to rectum were defined as right-sided or left-sided, respectively. In addition, exploratory RAS and BRAF mutation analyses were performed.

RESULTS

A total of 110 patients were assessable for tumor location; 90 had left-sided tumors. Left-sided tumors were significantly associated with longer overall survival (36.2 vs. 12.6 months, hazard ratio = 0.28, P < .0001) and progression-free survival (11.1 vs. 5.6 months, hazard ratio = 0.47, P = .0041) than right-sided tumors; similar results were obtained in multivariate analysis. A subanalysis showed that the association was evident in the FOLFOX group and that tumor location was an independent prognostic factor irrespective of BRAF status in RAS wild-type patients.

CONCLUSION

Primary tumor location might be a predictor of survival independent of BRAF status in mCRC patients who receive first-line cetuximab combined with oxaliplatin-based chemotherapy.

A genetic variant in Rassf1a predicts outcome in mCRC patients treated with cetuximab plus chemotherapy: results from FIRE-3 and JACCRO 05 and 06 trials

The Hippo pathway is involved in colorectal cancer (CRC) development and progression. The Hippo regulator Rassf1a is also involved in the Ras signaling cascade. In this work, we tested single nucleotide polymorphisms within Hippo components and their association with outcome in CRC patients treated with cetuximab. Two cohorts treated with cetuximab plus chemotherapy were evaluated (198 RAS wild-type (wt) patients treated with first-line FOLFIRI plus Cetuximab within the FIRE-3 trial and 67 Ras wt patients treated either with first-line mFOLFOX6 or SOX plus Cetuximab). In these two populations, Rassf1a rs2236947 was associated with overall survival, as patients with a CC genotype had significantly longer OS compared to those with CA or AA genotypes. This association was stronger in patients with left-side CRC [HR: 1.79 (1.01–3.14); P=0.044 and HR: 2.83 (1.14–7.03); P=0.025, for Fire 3 and JACCRO cohorts, respectively]. Rassf1a rs2236947 is a promising biomarker for patients treated with cetuximab plus chemotherapy.

Prognostic Implication of KRAS Status after Hepatectomy for Colorectal Liver Metastases Varies According to Primary Colorectal Tumor Location

BACKGROUND

Right-sided and left-sided colorectal cancer (CRC) is known to differ in their molecular carcinogenic pathways. We sought to investigate the variable prognostic implication of KRAS mutation after hepatectomy for colorectal liver metastases (CRLM) according to the site of primary CRC.

METHODS

A total of 426 patients who underwent a curative-intent hepatic resection and whose KRAS status was available were identified. Clinicopathologic characteristics and long-term outcomes were stratified by KRAS status (wild type vs. mutant type) and primary tumor location (right-sided vs. left-sided). Cecum, right and transverse colon were defined as right-sided, whereas left colon and rectum were defined as left-sided.

RESULTS

Among patients with a right-sided CRC, 5-year recurrence-free survival (RFS) and overall survival (OS) were not correlated with KRAS status (wild type: 30.8 and 47.2 % vs. mutant type: 38.5 and 49.1 %, respectively) (both P > 0.05). Specifically, mutant-type KRAS was not associated with either RFS or OS on multivariable analysis (hazard ratio [HR] 1.51, 95 % confidence interval [CI] 0.73-3.14, P = 0.23 and HR 1.03, 95 % CI 0.51-2.08, P = 0.95, respectively). In contrast, among patients who underwent resection of CRLM from a left-sided primary CRC, 5-year RFS and OS were worse among patients with mutant-type KRAS (wild type: 23.7 and 57.2 % vs. mutant type: 19.6 and 38.2 %, respectively) (both P < 0.05). On multivariable analysis, mutant-type KRAS remained independently associated with worse RFS and OS among patients with a left-sided primary CRC (HR 1.57, 95 % CI 1.01-2.44, P = 0.04 and HR 1.81, 95 % CI 1.11-2.96, P = 0.02, respectively).

CONCLUSIONS

KRAS status has a variable prognostic impact after hepatic resection for CRLM depending on the site of the primary CRC. Future studies examining the impact of KRAS status on prognosis after hepatectomy should take into account the primary CRC tumor site.

Prognostic and predictive value of extended RAS mutation and mismatch repair status in stage III colorectal cancer

The prognostic and predictive value of KRAS gene mutations in stage III colorectal cancer is controversial because many recent clinical trials have not involved a surgery-alone arm. Additionally, data on the significance of extended RAS (KRAS/NRAS) mutations in stage III cancer are not available. Hence, we undertook a combined analysis of two phase III randomized trials, in which the usefulness of adjuvant chemotherapy with tegafur-uracil (UFT) was evaluated, as compared with surgery alone. We determined the association of extended RAS and mismatch repair (MMR) status with the effectiveness of adjuvant chemotherapy. Mutations in KRAS exons 2, 3, and 4 and NRAS exons 2 and 3 were detected by direct DNA sequencing. Tumor MMR status was determined by immunohistochemistry. Total RAS mutations were detected in 134/304 (44%) patients. In patients with RAS mutations, a significant benefit was associated with adjuvant UFT in relapse-free survival (RFS) (hazard ratio = 0.49; P = 0.02) and overall survival (hazard ratio = 0.51; P = 0.03). In contrast, among patients without RAS mutations, there was no difference in RFS or overall survival between the adjuvant UFT group and surgery-alone group. We detected deficient DNA MMR in 23/304 (8%) patients. The MMR status was neither prognostic nor predictive for adjuvant chemotherapy. An interaction analysis showed that there was better RFS among patients treated with UFT with RAS mutations, but not for those without RAS mutations. Extended RAS (KRAS/NRAS) mutations are proposed as predictive indicators with respect to the efficacy of adjuvant UFT chemotherapy in patients with resected stage III colorectal cancer.

PTEN mRNA expression is less pronounced in left- than right-sided colon cancer: a retrospective observational study

BACKGROUND

Several recent studies have reported that patients with metastatic colorectal cancer (CRC) whose primary tumor is located in left side of the colon have more favorable responses to anti-epidermal growth factor receptor (EGFR) antibody therapy than those with right-sided tumors. However, the mechanism for this phenomenon is unknown.

METHODS

Fifty-two cases of primary CRC with liver metastases were analyzed in this retrospective study. The mRNA levels of 19 signal transduction genes in both primary tumor and liver metastases were measured by real-time reverse transcription polymerase chain reaction. The purposes of this study were (1) to determine the correspondence between signal transduction gene expressions in primary tumors and corresponding liver metastases, and (2) to determine whether expression levels of these genes differ by primary tumor location.

RESULTS

mRNA expression levels of 14 of 19 signal transduction genes, including PTEN, ERBB2, MET, HGF, AREG, and EREG, showed significant correlations between the primary tumor and corresponding liver metastases. When the mRNA levels of the primary tumors were compared by tumor location, only PTEN mRNA expression differed significantly between left and right-sided CRC (median PTEN expression: left 1.00 vs. right 1.68; p = 0.017). When rectal cancers were separated from left-sided colon cancers, PTEN mRNA levels increased progressively from rectum to right-sided colon (median; rectum 0.84, left colon 1.23, right colon 1.68, p = 0.013). PTEN mRNA expression in liver metastases also differed significantly according to primary tumor location (median; left 0.92 vs. right 1.27, p = 0.048). There was no difference in overall survival between patients with high versus low levels of PTEN mRNA (p = 0.59).

CONCLUSIONS

Our data suggest that the PIK3/AKT/mTOR pathway is more active in left- than right-sided CRC, which provides a possible explanation for the fact that efficacy of anti-EGFR therapy differs by location of primary tumor.

Primary tumor site is a useful predictor of cetuximab efficacy in the third-line or salvage treatment of KRAS wild-type (exon 2 non-mutant) metastatic colorectal cancer: a nationwide cohort study

BACKGROUND

Previous studies have shown left-sided colorectal cancer (LCRC) and right-sided colorectal cancer (RCRC) exhibit different molecular and clinicopathological features. We explored the association between the primary tumor site and cetuximab efficacy in KRAS wild-type colorectal cancer (CRC).

METHODS

This study enrolled a cohort of patients, who had received cetuximab treatment after two or more lines of chemotherapy for KRAS wild-type (exon 2 nonmutant) metastatic CRC, from the databases of Taiwan Cancer Registry (2004-2010) and National Health Insurance (2004-2011). Survival data were obtained from the National Death Registry. Time to treatment discontinuation (TTD) and overall survival (OS) after the start of cetuximab treatment were compared between patients with LCRC (splenic flexure to rectum) and RCRC (cecum to hepatic flexure).

RESULTS

A total of 969 CRC patients were enrolled. Among them, 765 (78.9 %) and 136 (14.0 %) patients had LCRC and RCRC, respectively. Patients with LCRC, compared to patients with RCRC, had longer TTD (median, 4.59 vs. 2.75 months, P = .0005) and OS (median, 12.62 vs. 8.07 months, P < .0001) after the start of cetuximab treatment. Multivariate analysis revealed a right-sided primary tumor site was an independent predictor of shorter TTD (adjusted hazard ratio [HR] = 1.32, using the LCRC group as a reference, 95 % confidence interval: 1.08-1.61, P = .0072) and OS (adjusted HR = 1.45, 95 % CI: 1.18-1.78, P = .0003).

CONCLUSION

Our findings demonstrate that a left-sided primary tumor site is a useful predictor of improved cetuximab efficacy in the third-line or salvage treatment of KRAS wild-type (exon 2 nonmutant) metastatic CRC.

Impact of Primary Tumor Site on Bevacizumab Efficacy in Metastatic Colorectal Cancer

BACKGROUND

With an ever-increasing focus on personalized medicine, all factors known to affect treatment response need to be considered when defining optimal therapy for individual patients. While the prognostic impact of primary tumor site on colorectal cancer (CRC) outcomes is established, emerging data suggest potential differences in response to biologic therapies. We studied the impact of tumor site on bevacizumab efficacy in patients with metastatic CRC.

PATIENTS AND METHODS

We analyzed data of patients in an Australian prospective multicenter metastatic CRC (mCRC) registry who received first-line chemotherapy. Tumor site was defined as right colon, cecum to transverse; left colon, splenic flexure to rectosigmoid; and rectum. Kaplan-Meier and Cox models were used for survival analyses.

RESULTS

Of 926 patients, 297 had right colon, 354 left colon, and 275 rectum primary disease. Median age was 68.6, 65.9, and 63.3 years, respectively (P = .001). Right colon disease was significantly associated with intraperitoneal spread (P < .0001), while left colon and rectum disease preferentially metastasized to the liver and lungs, respectively (P < .0001 in both settings). A total of 636 patients (68.7%) received bevacizumab. Progression-free survival was superior for bevacizumab-treated patients in all groups but appeared greatest in right colon disease (hazard ratio, 0.46; 95% confidence interval, 0.36-0.60; P ≤ .001). Overall survival was longest in patients with disease of the rectum, followed by left colon and right colon (median, 26.2, 23.6, and 18.2 months, respectively; P = .0004).

CONCLUSION

Tumor site appears to be prognostic in mCRC, with rectum and right colon disease associated with the best and worst outcomes, respectively. Patients who received bevacizumab in addition to chemotherapy had superior outcomes, with the effect appearing greatest in patients with right colon disease.

Detection of Polyps After Resection of Colorectal Cancer

Purpose

Because colonoscopy after colorectal cancer surgery is important for detecting synchronous or metachronous colorectal neoplasms, we designed this study to investigate, by using postoperative colonoscopy, the miss rate for and the location of polyps remaining after colorectal cancer surgery.

Methods

In a prospectively-collected patient database, 264 patients were shown to have undergone a colorectal cancer resection between May 2012 and June 2013. Of these, 116 who had received a complete colonoscopy preoperatively and postoperatively were included in this study.

Results

Of these 116 patients, 68 were males and 48 were females; their mean age was 63 years. The mean time after surgery at which postoperative colonoscopy was performed was 7.1 months (range, 3-15 months). On postoperative colonoscopy, a total of 125 polyps were detected. Of these, there were no cancerous lesions; 46 (36.8%) were neoplastic polyps, and 79 (63.2%) were nonneoplastic polyps. Fifty-nine polyps (47.2%) and 15 polyps (12%) were located in the proximal and the distal parts of the anastomosis, respectively. The miss rates for the total numbers of polyps and of neoplastic polyps remaining after surgery were 37.4% and 24.2%, respectively. The incidence of neoplastic polyps increased during postoperative colonoscopy as it had during preoperative colonoscopy (r = 0.164, P = 0.048).

Conclusion

Colonoscopic surveillance after colorectal cancer resection results in the detection of pathologic polyps in one-fourth of the cases. During postoperative colonoscopy, careful examination of the proximal colon is necessary. Patients in whom multiple neoplastic polyps had been detected during preoperative colonoscopy require careful and thorough follow-up.