Impact of KRAS and TP53 mutations on survival in patients with left- and right-sided Dukes' C colon cancer

Multi-omic analysis reveals metabolic pathways that characterize right-sided colon cancer liver metastasis

There are well demonstrated differences in tumor cell metabolism between right sided (RCC) and left sided (LCC) colon cancer, which could underlie the robust differences observed in their clinical behavior, particularly in metastatic disease. As such, we utilized liquid chromatography-mass spectrometry to perform an untargeted metabolomics analysis comparing frozen liver metastasis (LM) biobank samples derived from patients with RCC (N = 32) and LCC (N = 58) to further elucidate the unique biology of each. We also performed an untargeted RNA-seq and subsequent network analysis on samples derived from an overlapping subset of patients (RCC: N = 10; LCC: N = 18). Our biobank redemonstrates the inferior survival of patients with RCC-derived LM (P = 0.04), a well-established finding. Our metabolomic results demonstrate increased reactive oxygen species associated metabolites and bile acids in RCC. Conversely, carnitines, indicators of fatty acid oxidation, are relatively increased in LCC. The transcriptomic analysis implicates increased MEK-ERK, PI3K-AKT and Transcription Growth Factor Beta signaling in RCC LM. Our multi-omic analysis reveals several key differences in cellular physiology which taken together may be relevant to clinical differences in tumor behavior between RCC and LCC liver metastasis.

Colorectal adenocarcinoma in Uganda: are right-sided and left-sided colon cancers two distinct disease entities?

INTRODUCTION

In Western countries, right-sided colon cancers (RSCC) present at an older age and advanced stage. Researchers believe that there is a difference between left-sided colon cancer (LSCC) and RSCC. In Uganda, however, it is unknown whether differences exist in the pathological profile between RSCC and LSCC. The aim of this study was to determine the differences in clinicopathological characteristics between RSCC and LSCC in Ugandan patients.

METHODOLOGY

A cross-sectional study was conducted in which colorectal adenocarcinoma formalin-fixed paraffin-embedded tissue (FFPE) blocks were obtained from 2008 to 2021. Colorectal specimens were obtained from prospectively recruited patients. In the retrospective study arm, FFPE blocks and data were obtained from the archives of pathology laboratory repositories. Parameters studied included age, sex, location of the tumour, grade, stage, lymphovascular (LVI) status, and histopathological subtype between LSCC and RSCC.

RESULTS

Patients with RSCC were not older than those with LSCC (mean age, 56.3 years vs 53.5 years; p = 0.170). There was no difference in the stage between RSCC and LSCC. Poorly differentiated tumours were more commonly found in RSCC than in LSCC (18.7% vs 10.1%; p = 0.038). Moderately and poorly differentiated colonic tumours were more common with RSCC (89.3%) than with LSCC (75.1%) (p = 0.007). Younger patients had more poorly differentiated tumours than older patients (19.6% versus 8.6%; p = 0.002). LVI was more common with RSCC than with LSCC (96.8% vs 85.3%; p = 0.014). Mucinous adenocarcinoma (MAC) was more common with RSCC (15.8%) compared with LSCC (8.5%) (p = 0.056) although statistical significance was borderline.

CONCLUSIONS

Clinicopathological features of RSCCs tend to be different from those of LSCCs. RSCCs tend to be associated with MAC, a higher grade and LVI status compared to LSCC. LSCC and RSCC present predominantly with an advanced stage; therefore, national screening programmes for the early detection of CRC are necessary to reduce mortality in our Ugandan population.

Tumor profiling of KRAS, BRAF, and NRAS gene mutations in patients with colorectal cancer: A Lebanese major center cohort study

BACKGROUND

In the era of precision medicine, treatment schemes for advanced Colorectal (CRC) disease include monoclonal antibodies which block the epidermal growth factor receptor (EGFR) implicated in tumor proliferation, invasion, migration and neovascularization. Resistance to these agents has been correlated with activating downstream mutations in KRAS, BRAF and NRAS genes, among others, leading to constitutive activation of the EGFR axis bypassing EGFR blockade. The assessment of tumor RASandBRAFmutational status has thus become standard clinical practice. While multiple investigations reported roughly mutations rates of 40% in KRAS, 7% in NRAS and 5-15 % in BRAF, numbers vary across different populations with limited data specifically from the Middle East.

METHODS

This is a retrospective observational Laboratory information system (LIS) chart review of all the patients with pathologically confirmed colorectal carcinoma (CRC) or metastatic CRC who underwent KRAS, NRAS and/or BRAF mutational analysis testing at the Molecular Diagnostics Laboratory of the American University of Beirut Medical Center (AUBMC) from January 2012 to December 2018, inclusive. Data retrieved included the results of mutation testing performed for KRAS, NRAS and BRAF genes, the age, gender, and tumor location for each patient. Analysis of the mutations was performed using polymerase chain reaction (PCR) hybridization StripAssay® (ViennaLab, Vienna, Austria).

RESULTS

130 (47.6%) out of 273 histologically confirmed CRC cases, had positive KRAS mutations, namely in codons 12 (82%), 13 (17%), 146 (1.5%), 117 (0.75%), or 61 (0.75%). Two patients had two concomitant mutations: 12 + 12 (different mutations) and 12 + 146. Of 203 CRC cases tested for NRAS mutations, 16 (7.8%) were found to be positive for a mutation in codon 12 (37.5%), 61 (37.5%), or 13 (12.5%). Two patients had two concomitant mutations: 12 + 13 and 59 + 61. Of 172 CRC cases tested for BRAF mutations, 2 (1.2 %) were positive for the V600E -.

CONCLUSION

This retrospective study is the first to report the frequencies of KRAS, NRAS and BRAF gene mutations in a Lebanese CRC cohort diagnosed and managed at a tertiary care center. The frequencies of the studied somatic gene mutations were similar to previously reported cohorts in other populations however the rate of BRAF mutation was lower in this cohort than expected.

KRAS Mutations in Colorectal Cancer: Relationship With Clinicopathological Characteristics and Impact on Clinical Outcomes in Saudi Arabia

Background

Few studies have addressed the prevalence and prognostic impacts of KRAS mutations in Saudi patients with colorectal cancer (CRC). The present study aimed to address the prevalence of KRAS mutations and evaluate their impact on clinical outcomes (if any) among Saudi patients.

Methods

This retrospective cohort study was conducted at King Saud University Medical Centre (KSUMC), Saudi Arabia. All medical records of biopsy-proven CRC patients between 2015 and 2021 were reviewed. Statistical analysis was carried out to address the associations between KRAS mutations and the clinicopathological patients’ variables and survival.

Results

KRAS mutations were found in 97/194 (50%) CRC patients. In comparison to wild type KRAS tumors, KRAS- mutated ones had shown a trend toward right-sided tumors (30% and 4.3% vs 16% and 1.1%, p-value = 0.032, respectively) and peritoneal metastases (34% vs 19%, p-value = 0.014). Older age at diagnosis, gender, tumor grade, microsatellite instability (MSI), tumor stage (T), and the presence of distant metastasis were independent prognostic factors for poor overall survival (OS). There was no significant association between KRAS mutations and the hazard of mortality (HR: 0.653, 95% CI 0.873-1.134, p = 0.131). For progression-free survival (PFS), older age at presentation, MSI, tumor nodal stage (N), the presence of liver and lung metastasis, and recurrence were poor prognostic factors for PFS. There was no significant relation between KRAS mutations and PFS (HR ratio: 0.756, 95% CI 0.229-2.497, p = 0.646).

Conclusions

The prevalence of KRAS mutations in CRC patients was similar to that observed in previous studies of Saudi patients. KRAS mutations showed a trend toward right-sided tumors and peritoneal metastases. Survival was significantly related to different clinicopathologic variables of the study cohort but was not affected by the KRAS mutational status.

Prognostic Value of BRAF and KRAS Mutation in Relation to Colorectal Cancer Survival in Iranian Patients: Correlated to Microsatellite Instability

PURPOSE

To evaluate the prognostic role of BRAF and KRAS mutations after adjustment for microsatellite instability (MSI) in Iranian colorectal cancer (CRC) patients.

METHODS

BRAF and KRAS mutations and MSI status were assessed in 258 Iranian subjects with CRC. Two hundred fifty-eight consecutive stages I-IV CRC patients, who underwent surgical resection of adenocarcinoma from 2012 to 2016, were enrolled in the research. Pyrosequencing and Cast-PCR methods were used to the detection of KRAS and BRAF mutations. Kaplan-Meier and Cox regression were employed to estimate hazard ratios (HR) for the association between BRAF and KRAS mutation and overall survival (OS).

RESULTS

KRAS and BRAF mutations were detected in 36 (14%) and 15 (5.8%) cases of 258 patients with CRC, respectively. BRAF mutations that all comprised V600E and KRAS mutations was found in codon 12 and 13 (80.6% and 19.4%), respectively. KRAS mutations were detected in 19 (15.4%) patients of 123 microsatellite stable (MSS) CRC and it is significantly associated with tumor location and metastasis. BRAF and KRAS mutant vs. wild type of BRAF and KRAS, 5-year OS was 73.3% vs. 82.3% and 83.3% vs. 81.5% (long-rank P > 0.05), respectively. KRAS mutant vs. KRAS-wild-type tumors in MSS/MSI-L status CRC patients, 5-year OS was 78.9% vs. 90.4% (long-rank p = 0.046).

CONCLUSION

The present study revealed that BRAF and KRAS mutations were not related to the worse overall survival, while KRAS mutation can be a prognostic factor for overall survival in sporadic microsatellite-stable (MSS) status in Iranian CRC patients.

Multitarget stool DNA test compared with fecal occult blood test for colorectal cancer screening

Patient screening is important for early diagnosis of colorectal cancer (CRC). The present study aimed to compare the multitarget stool DNA (mt-sDNA) test with the fecal occult blood test (FOBT) for CRC screening. A total of 151 individuals were screened using colonoscopy, mt-sDNA and FOBT for the detection of CRC and adenoma. The results of the mt-sDNA test and FOBT were compared with colonoscopy to examine their sensitivity and specificity. Subsequently, the sensitivity and specificity of the mt-sDNA test were compared with those of FOBT in CRC and large adenoma. Stool samples were collected from patients with CRC (n=50) or large adenoma (n=51), as well as from normal controls (n=50). The mt-sDNA test outperformed FOBT in detecting CRC with a sensitivity of 90.0% (45/50) vs. 42.0% (21/50), advanced adenoma with a sensitivity of 70.6% (36/51) vs. 19.6% (10/51), stage I–III CRC with a sensitivity of 91.9% (34/37) vs. 29.7% (11/37), and stage IV CRC with a sensitivity of 84.6% (11/13) vs. 76.9% (10/13). In addition, the mt-sDNA test exhibited a specificity of 94.0% (47/50) in detecting CRC, which was superior to FOBT with a specificity of 90.0% (45/50). Therefore, the mt-sDNA test may have higher sensitivity and specificity compared with FOBT in diagnosing both CRC and advanced adenoma.

Angiotensin I-converting enzyme inhibitors/angiotensin II receptor blockers may reduce tumor recurrence in left-sided and early colorectal cancers

BACKGROUND

Angiotensin signaling is suggested to be involved in tumorigenesis, tumor proliferation, and metastases. In colorectal cancer (CRC), it was demonstrated that angiotensin I-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) may reduce the risk of CRC; however, their impact on tumor recurrence remains unknown. Therefore, in this study, we evaluated the impact of ACEIs/ARBs on tumor recurrence in CRC patients.

PATIENTS AND METHODS

We retrospectively investigated the clinicopathological data of 461 stage I-III CRC patients. We divided the patients into those who took an ACEI and/or ARB (the ACEI/ARB+ group) and those who did not (the ACEI/ARB- group), and we compared the two groups' recurrence-free survival (RFS) using a Kaplan-Meier curve analysis and log rank test. We also examined the impact of AGTR1 expression on tumor recurrence, using two public CRC datasets.

RESULTS

The Kaplan-Meier curves showed a trend toward improved RFS in the ACEI/ARB+ group versus the ACEI/ARB- group (p = 0.063). Subgroup analyses demonstrated that the RFS was significantly better in the ACEI/ARB+ group versus the ACEI/ARB- group in the patients with left-sided CRC (p = 0.030) and those with stage I CRC (p = 0.009). Consistent with these findings, the AGTR1 expression was higher in the left-sided versus right-sided colon (p = 0.048). High AGTR1 expression levels were associated with poor RFS in the GSE39582 dataset's stage I-III CRC patients (p < 0.001), and this finding was also validated in the GSE17536 dataset (p = 0.023).

CONCLUSION

ACEI/ARB treatment may reduce tumor recurrence in left-sided CRC and early-stage CRC.

Lymph node yield and tumour subsite are associated with survival in stage I-III colon cancer: results from a national cohort study

BACKGROUND

It has been suggested that apart from tumour and nodal status, a range of patient-related and histopathological factors including lymph node yield and tumour location seems to have prognostic implications in stage I-III colon cancer. We analysed the prognostic implication of lymph node yield and tumour subsite in stage I-III colon cancer.

METHODS

Data on patients with stage I to III adenocarcinoma of the colon and treated by curative resection in the period from 2003 to 2011 were extracted from the Danish Colorectal Cancer Group database, merged with information from the Danish National Patient Register and analysed.

RESULTS

A total of 13,766 patients were included in the analysis. The 5-year overall survival ranged from 59.3% (95% CI 55.7-62.9%) (lymph node yield 0-5) to 74.0% (95% CI 71.8-76.2%) (lymph node yield ≥ 18) for patients with stage I-II disease (p < 0.0001) and from 36.4% (95% CI 29.8-43.0%) (lymph node yield 0-5) to 59.4% (95% CI 56.6-62.2%) (lymph node yield ≥ 18) for patients with stage III disease (p < 0.0001). The 5-year overall survival for tumour side left/right was 59.3% (95% CI 57.9-60.7%)/64.8% (CI 63.4-66.2%) (p < 0.0001). In the seven colonic tumour subsites, the 5-year overall survival ranged from 56.6% (95% CI 51.8-61.4%) at splenic flexure to 65.8% (95% CI 64.5-67.2%) in the sigmoid colon (p < 0.0001). In a cox regression analysis, lymph node yield and tumour side right/left were found to be prognostic factors. Tumours at the hepatic and splenic flexures had an adverse prognostic outcome.

CONCLUSION

For stage I-III colon cancer, a lymph node yield beyond the recommended 12 lymph nodes was associated with improved survival. Both subsite in the right colon, as well as subsite in the left colon, turned out with adverse prognostic outcome questioning a simple classification into right-sided and left-sided colon cancer.

Impact of primary colorectal Cancer location on the KRAS status and its prognostic value

BACKGROUND

Colorectal cancer (CRC) originating from the right-sided or left-sided colon is distinct clinicopathological entity. The KRAS status and its prognostic value in CRC remain controversial. This study aimed to investigate the association of KRAS status with clinicopathological features and prognostic value in CRC.

METHODS

178 colon cancer and 145 rectal cancer patients were enrolled. KRAS mutation test was performed on paraffin-embedded tumor samples using PCR methods. The colon cancer was divided into right-sided colon cancer (RCC) and left-sided colon cancer (LCC). Studies that reported the association of KRAS mutation with CRC clinical features and prognosis in databases were searched prior to 2018. The data of the present study was combined with the data of published studies using meta-analysis methods.

RESULTS

No significant difference between colon cancer and rectal cancer regarding the KRAS status. The KRAS mutation was much frequent in RCC than in LCC (p = 0.010). 17 studies with 11,385 colon cancer patients were selected, the pooled results of our data and previous published data showed that KRAS mutation was more frequent in RCC compared with in LCC (p < 0.01); KRAS mutation was not associated with the prognosis in RCC patient; however, KRAS mutation indicated a poor prognosis in LCC patients compared with KRAS wild type (p < 0.01).

CONCLUSION

KRAS status has no difference between colon cancer and rectal cancer. KRAS mutation was more frequent in RCC than in LCC, and associated with a poor prognosis in LCC patients, but not in RCC patients.

Right or Left Primary Site of Colorectal Cancer: Outcomes From the Molecular Analysis of the AGITG MAX Trial

BACKGROUND

For metastatic colorectal cancer, previous reports have described differences in biology and outcome, including response to biologic agents, based on whether the primary tumor is right- or left-sided. We explored the molecular markers from the AGITG MAX trial.

PATIENTS AND METHODS

The AGITG MAX trial was a randomized study comparing capecitabine versus capecitabine + bevacizumab versus capecitabine + bevacizumab + mitomycin C as first-line therapy in advanced colorectal cancer. Patients were classified as having right-sided (caecum to transverse colon) or left-sided (descending colon to rectum) disease according to anatomic location. Baseline characteristics and previously described molecular profiles were compared by side of primary tumor. Survival outcomes were analyzed by the Kaplan-Meier approach and proportional hazards regression modeling.

RESULTS

Among the 471 patients, the location of primary tumor was known in 440 patients (93%). Molecular profile was known in 298 patients (63%). Twenty-eight percent had right-sided primary tumors. Major differences between right and left are as follows: female 49% versus 33% (P < .01), BRAF mutant 16% versus 3.5% (P ≤ .001), and phosphatase and tensin homolog (PTEN) loss 27.6% versus 53% (P = .01). There were no differences in RAS mutation, PIK3CA mutation, or high versus low expression of assessed angiogenic markers. Right-sided primary lesion predicted a poor outcome for median overall survival: right-sided disease 13.2 months versus left-sided disease 20 months (P = .001; hazard ratio [HR] = 0.67; 95% confidence interval [CI], 0.53-0.85), but not for progression-free survival (HR 0.96; 95% CI, 0.78-1.20). The relative treatment effect did not differ significantly according to location of primary tumor: right primary tumor HR (bevacizumab containing arm vs. capecitabine monotherapy arm) was 0.82 (95% CI, 0.54-1.22), and left primary HR (bevacizumab containing arm vs. capecitabine monotherapy arm) was 0.51 (95% CI, 0.4-0.63) (interaction P = .10).

CONCLUSION

There are more negative prognostic factors in patients with right-sided primary tumors, in particular high BRAF mutations, and these patients have inferior overall survival compared to those with a left-sided primary tumor. There was no suggestion that side of primary site had any impact on bevacizumab effect on progression-free survival.

Correlation between vascular endothelial growth factor-A expression and tumor location and invasion in patients with colorectal cancer

Background

Vascular endothelial growth factor-A (VEGF-A) has been observed as the predominant angiogenic factor in colorectal cancer (CRC) and the assessment of microvessel density (MVD) has been used to quantify tumor neoangiogenesis. This study aimed to determine clinicopathological and prognostic significance of both angiogenic markers in the local CRC patients.

Methods

We analyzed tissue samples obtained from 81 cases with CRC. VEGF-A expression and MVD counts were immunohistochemically detected using anti VEGF-A and CD31. The assessments of both markers were classified as low and high. Correlation between VEGF-A expression and MVD value and clinicopathological characteristics were examined using Chi-square test. The overall survival (OS) was plotted using the Kaplan-Meier method.

Results

High VEGF-A expression was found more frequently in the rectal location (P=0.042) and T4 tumors (P=0.041) compared to their counterparts. Older patients tended to show a higher MVD value compared to younger cases (P=0.062). In addition, survival analysis showed that males had a worse OS compared to females (P=0.029), and VEGF-A expression and MVD count did not correlate with patients' survival.

Conclusions

There were significant differences of VEGF-A expression according to tumor location and T invasion. Sex, but not angiogenic markers, had an influence on the survival of CRC patients.

Different Anatomical Subsites of Colon Cancer and Mortality: A Population-Based Study

Background

In terms of incidence and pathogenesis, right-sided colon cancer (RCC) and left-sided colon cancer (LCC) exhibit several differences. However, whether existing differences could reflect the different survival outcomes remains unclear. Therefore, we aimed to ascertain the role of location in the prognosis.

Methods

We identified colon cancer cases from the Surveillance, Epidemiology, and End Results database between 1973 and 2012. Differences among subsites of colon cancer regarding clinical features and metastatic patterns were compared. The Kaplan-Meier curves were conducted to compare overall and disease-specific survival in relation to cancer location. The effect of tumour location on overall and cancer-specific survival was analysed by Cox proportional hazards model.

Results

A total of 377,849 patients from SEER database were included in the current study, with 180,889 (47.9%) RCC and 196,960 (52.1%) LCC. LCC was more likely to metastasize to the liver and lung. Kaplan-Meier curves demonstrated that LCC patients had better overall and cancer-specific survival outcomes. Among Cox multivariate analyses, LCC was associated with a slightly reduced risk of overall survival (HR, 0.92; 95% CI, 0.92-0.93) and cancer-specific survival (HR, 0.92; 95% CI, 0.91-0.93), even after adjusted for other variables. However, the relationship between location and prognosis was varied by subgroups defined by age, year at diagnosis, stage, and therapies.

Conclusions

We demonstrated that LCC was associated with better prognosis, especially for patients with distant metastasis. Future trails should seek to identify the underlying mechanism.

Calcitriol Supplementation Causes Decreases in Tumorigenic Proteins and Different Proteomic and Metabolomic Signatures in Right versus Left-Sided Colon Cancer

Vitamin D deficiency is a common problem worldwide. In particular, it is an issue in the Northern Hemisphere where UVB radiation does not penetrate the atmosphere as readily. There is a correlation between vitamin D deficiency and colorectal cancer incidence and mortality. Furthermore, there is strong evidence that cancer of the ascending (right side) colon is different from cancer of the descending (left side) colon in terms of prognosis, tumor differentiation, and polyp type, as well as at the molecular level. Right-side tumors have elevated Wnt signaling and are more likely to relapse, whereas left-side tumors have reduced expression of tumor suppressor genes. This study seeks to understand both the proteomic and metabolomic changes resulting from treatment of the active metabolite of vitamin D, calcitriol, in right-sided and left-sided colon cancer. Our results show that left-sided colon cancer treated with calcitriol has a substantially greater number of changes in both the proteome and the metabolome than right-sided colon cancer. We found that calcitriol treatment in both right-sided and left-sided colon cancer causes a downregulation of ribosomal protein L37 and protein S100A10. Both of these proteins are heavily involved in tumorigenesis, suggesting a possible mechanism for the correlation between low vitamin D levels and colon cancer.

KRAS mutation and primary tumor location do not affect efficacy of bevacizumab-containing chemotherapy in stagae IV colorectal cancer patients

This study aims to investigate the efficacy of bevacizumab-combined chemotherapy (BCC) in Chinese stage IV colorectal cancer (CRC), and analyze the relationship between clinicopathological features with survival. Patients with stage IV CRC treated with BCC were analyzed retrospectively. 217 metastatic CRC (mCRC) patients were collected, out of which79 were right-sided CRCs and 138 were left-sided ones. Patients with Eastern Cooperative Oncology Group (ECOG) performance status ≤2, single agent chemotherapy, poor/mucous/signet ring cell component, second-and further-line of bevacizumab administration, multiple metastasis sites had comparatively worse survival. Among 141 patients with known KRAS status, 55 patients harbored KRAS mutation and 86 had wild type KRAS. The ORR and DCR were 41.9% and 78.9%, respectively, in patients with wild type KRAS, while ORR and DCR was 38.7% and 77.9%, respectively, in patients with KRAS mutation. The median PFS of patients with wild type and mutant KRAS were 8.38, and9.59 months, respectively; whereas the OS was 23.00 and 21.26 months, respectively for mCRC patients with wild-type and mutant KRAS. Cumulatively, our study indicated that BCC was effective and beneficial for Chinese stage IV CRC patients. KRAS mutation status and tumor location were not a prognostic factor for survival.

Association between clinicopathological features and survival in patients with primary and paired metastatic colorectal cancer and KRAS mutation

The KRAS gene mutation is involved in several types of tumors. However, the potential role of the KRAS mutation in human primary and paired metastatic colorectal cancer (CRC) among different nationalities is poorly understood. In the present study, we assessed the relationship between KRAS mutation status and overall survival (OS) and disease-free survival (DFS) in 230 patients with primary and paired metastatic CRC. The KRAS mutation rate in primary CRC tissue was 43.0% (99/230), which was higher than in paired metastatic CRC, which was 31.9% (23/72; P<0.001). Clinicopathologically, the KRAS gene mutation rate was higher in tumors that had infiltrated more deeply (T3, T4) and in lymph node (LN) metastases (N1/N2) (P=0.029 and P=0.010, respectively). The KRAS gene status did not differ between the Han and Uyghur nationalities in both primary and metastatic CRC. In 72 paired cases, the KRAS mutation rate in primary CRC was significantly higher than in metastatic CRC (P<0.001) and in metastatic CRC that had infiltrated more deeply (T3, T4) (P=0.034). In the metastatic cases, the KRAS gene mutation rate was higher in patients aged over 65 years (P=0.035). Specifically, KRAS mutation was correlated with a poorer OS and DFS (P=0.004 and P=0.029, respectively). In our study, 35 patients with wild-type KRAS who received cetuximab targeted therapy had a better DFS than patients with mutant KRAS (P=0.029). The results of the current study demonstrate that the KRAS status is significantly associated with infiltrating LN metastases and the TNM stage in primary CRC. In addition, the results show that the KRAS mutation is significantly more common in primary tumors than in paired metastatic CRC, and the KRAS mutation is correlated with a shorter OS and DFS, as patients with wild-type KRAS who received cetuximab experienced a longer DFS.

Molecular differences in the microsatellite stable phenotype between left-sided and right-sided colorectal cancer

Differences in the pathogenesis of microsatellite stable (MSS) sporadic colorectal cancers (CRCs) between left‐sided CRC (LC) and right‐sided CRC (RC) have not been clarified. To identify pathogenesis‐related genomic differences between MSS CRCs within the two locations, we performed a comprehensive molecular analysis using crypt isolation with samples from 92 sporadic CRCs. Microsatellite instability (MSI; high and low/negative) and DNA methylation status (low methylation epigenome; intermediate methylation epigenome [IME] or high methylation epigenome [HME]) were determined using polymerase chain reaction (PCR) microsatellite analysis and PCR‐bisulfite pyrosequencing, respectively. Additionally, mutations in the TP53, KRAS, BRAF and PIK3CA genes were examined using PCR‐bisulfite pyrosequencing (for KRAS and BRAF mutations) or PCR‐single conformation polymorphism (for TP53 and PIK3CA mutations), followed by sequencing of aberrant bands. Finally, a genome‐wide study using a copy number alteration (CNA)‐targeted single nucleotide polymorphism array was performed. Ninety‐two CRCs were classified into 71 MSS and 21 MSI phenotypes. We examined 71 CRCs with the MSS phenotype (LC, 56; RC, 15). Mutations in KRAS were associated with RC with the MSS phenotype, whereas mutations in TP53 were more frequently found in LC with the MSS phenotype. There were significant differences in the frequencies of KRAS and TP53 mutations in the IME between LC and RC with the MSS phenotype. Although CNA gains were associated with LC with the MSS phenotype, CNA losses were not major alterations associated with the MSS phenotype. These findings suggested that the molecular pathogenesis of the MSS phenotype in LC was different from that in RC.

What's new?

The classification of colorectal cancer (CRC) based on tumor location is simple, comprehensive, and consistent with recent attempts to characterize tumors by pathological and molecular features. Differences in the pathogenesis of microsatellite stable (MSS) sporadic CRCs between left‐sided CRC (LC) and right‐sided CRC (RC) have however not been clarified. Here, the authors found that TP53 mutations are closely associated with the development of LC whereas RC is characterized by KRAS mutations. Using an integrated genome‐wide analysis, they also show significant differences in copy number alterations. The findings suggest a different molecular pathogenesis of the MSS phenotype between LC and RC.

RAS testing practices and RAS mutation prevalence among patients with metastatic colorectal cancer: results from a Europe-wide survey of pathology centres

BACKGROUND

Treatment options for patients with metastatic colorectal cancer (mCRC) include anti-epithelial growth factor therapies, which, in Europe, are indicated in patients with RAS wild-type tumours only and require prior mutation testing of "hot-spot" codons in exons 2, 3 and 4 of KRAS and NRAS. The aim of this study was to evaluate the implementation of RAS testing methods and estimate the RAS mutation prevalence in mCRC patients.

METHODS

Overall, 194 pathology laboratories were invited to complete an online survey. Participating laboratories were asked to provide information on their testing practices and aggregated RAS mutation data from 20 to 30 recently tested patients with mCRC.

RESULTS

A total of 96 (49.5 %) laboratories across 24 European countries completed the survey. All participants tested KRAS exon 2, codons 12 and 13. Seventy (72.9 %) laboratories reported complete testing of all RAS hot-spot codons, and three (3.1 %) reported only testing KRAS exon 2. Sixty-nine (71.9 %) laboratories reported testing >80 patients yearly for RAS mutation status. Testing was typically performed within the reporting institution (93.8 %, n = 90), at the request of a treating oncologist (89.5 %, n = 85); testing methodology varied by laboratory and by individual codon tested. For laboratory RAS testing, turnaround times were ≤10 working days for the majority of institutions (90.6 %, n = 87). The overall crude RAS mutation prevalence was 48.5 % (95 % confidence interval: 46.4-50.6) for laboratories testing all RAS hot-spot codons. Prevalence estimates varied significantly by primary tumour location, approximate number of patients tested yearly and indication given for RAS testing.

CONCLUSION

Our findings indicate a rapid uptake of RAS testing in the majority of European pathology laboratories.

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.

The Worse Prognosis of Right-Sided Compared with Left-Sided Colon Cancers: a Systematic Review and Meta-analysis

BACKGROUND

Right-sided colon cancers (RCC) and left-sided colon cancers (LCC) are of different embryological origins, and various differences exist between them. However, the survival difference has not been assessed. The aim of this meta-analysis was to quantify the prognostic differences between RCC and LCC.

METHODS

Fifteen studies that compared the prognosis of colon cancer according to tumor location were identified. The effects of tumor location on survival outcome were assessed.

RESULTS

Patients with RCC had a significantly worse prognosis than did those with LCC in overall survival (OS) (hazard ratio (HR) = 1.14, 95 % confidence interval (CI) 1.06-1.22, p < 0.01). Our subgroup analyses demonstrated significant prognostic differences in Western countries (HR = 1.15, 95 % CI 1.08-1.23, p < 0.01), a nationwide database (HR = 1.15, 95 % CI 1.05-1.27, p = 0.01), and a stage-adjusted analysis (HR = 1.14, 95 % CI 1.05-1.24, p < 0.01).

CONCLUSIONS

These findings demonstrate that tumor location is associated with prognosis in colorectal cancer patients, and those with RCC have a significantly worse prognosis than those with LCC in terms of OS. RCC should be treated distinctively from LCC, and the establishment of standardized management for colon cancer by tumor location is needed.

Clinical significance of differential expression of interleukin 8 mRNA in left-sided and right-sided colon cancer

AIM: To investigate the differential expression of interleukin 8 (IL-8) between left-sided and right-sided colon cancer and to analyze its clinical significance.

METHODS: Eighty patients who received radical resection for stage II or III colon cancer were involved, including 40 patients with left-sided colon cancer (LSCC) and 40 with right-sided colon cancer (RSCC). Paired cancer and normal colon mucosal specimens were collected from each patient. The gene expression of IL-8 was detected by real-time quantitative PCR. Subsequently, the relationship between IL-8 expression and clinicopathological variables as well as prognosis was analyzed.

RESULTS: The mRNA expression of IL-8 in colon cancer was significantly higher than that in normal colon mucosa (P < 0.01). IL-8 expression was significantly higher in RSCC than in LSCC (P = 0.004). High IL-8 expression was closely related with RSCC (65% vs 35%, P = 0.007), bigger tumor size (5.2 cm vs 4.1 cm, P = 0.014) and tumor infiltrating lymphocytes (27.5% vs 10%,P = 0.045). In patients with LSCC, the survival of patients with high IL-8 expression was significantly shorter than that in patients with low IL-8 expression (37.0 mo vs 59.2 mo, P = 0.006). However, among patients with RSCC, patients with high IL-8 expression tended to have a better prognosis than patients with low expression (63.8 mo vs 54.5 mo, P = 0.151). Multivariate analysis demonstrated that T4 infiltration (RR = 6.514, 95%CI: 1.209-35.102, P = 0.029) and lymphatic/vascular invasion (RR = 6.272, 95%CI: 1.352-29.092, P = 0.019) were independent prognostic factors of RSCC, and high IL-8 expression (RR = 3.279, 95%CI: 0.973-11.051, P = 0.045), T4 infiltration (RR = 4.546, 95%CI: 1.335-15.481, P = 0.015), lymph node metastasis (RR = 5.918, 95%CI: 1.439-24.334, P = 0.014) and lymphatic/vascular invasion (RR = 3.663, 95%CI: 1.089-12.320, P = 0.036) were independent prognostic factors of LSCC.

CONCLUSION: The gene expression of IL-8 is significantly different between RSCC and LSCC. High IL-8 expression has a different prognostic impact on RSCC and LSCC. RSCC and LSCC are two potentially heterogeneous groups with differences in molecular and carcinogenic mechanisms.

Right-sided colon cancer and left-sided colorectal cancers respond differently to cetuximab

INTRODUCTION

Right-sided colon cancer (RSCC) and left-sided colorectal cancer (LSCRC) differ with respect to their biology and genomic patterns. This study aimed to examine whether the primary tumor location is associated with the response to cetuximab in patients with metastatic colorectal cancer (mCRC).

METHODS

Patients with mCRC treated with cetuximab and standard chemotherapy as first- or second-line treatments were compared with randomly chosen patients who were treated with chemotherapy alone between 2005 and 2013. The main outcome measures were the overall response rate (ORR), progression-free survival (PFS), and overall survival (OS). The differences in the outcome were analyzed by using the chi-squared test, Student's t test, and Kaplan-Meier method.

RESULTS

The treatment results of 206 patients with mCRC treated with cetuximab and standard chemotherapy as first- or second-line treatments were compared with those of 210 patients who were treated with chemotherapy alone. As a first-line treatment, cetuximab with chemotherapy was associated with a significantly higher ORR (49.4 % vs. 28.6 %, P = 0.005) as well as longer PFS (9.1 vs. 6.2 months, P = 0.002) and OS (28.9 vs. 20.1 months, P = 0.036) than chemotherapy alone in patients with LSCRC. However, cetuximab neither improved the ORR (36.4 % vs. 26.2 %, P = 0.349) nor prolonged PFS (5.6 vs. 5.7 months, P = 0.904) or OS (25.1 vs. 19.8 months, P = 0.553) in patients with RSCC. As a second-line treatment, cetuximab exhibited a tendency to improve the ORR (23.5 % vs. 10.2 %, P = 0.087) and prolong PFS (4.9 vs. 3.5 months, P = 0.064), and it significantly prolonged OS (17.1 vs. 12.4 months, P = 0.047) compared with chemotherapy alone in the patients with LSCRC. In contrast, as a second-line treatment, cetuximab neither improved the ORR (7.1 % vs. 11.4 %, P = 0.698) nor prolonged PFS (3.3 vs. 4.2 months, P = 0.761) or OS (13.4 vs. 13.0 months, P = 0.652) in patients with RSCC.

CONCLUSIONS

The addition of cetuximab to chemotherapy in both first- and second-line treatments of mCRC may only benefit patients with primary LSCRC.

Cyclin-dependent kinase inhibitors and the treatment of gastrointestinal cancers

The cell cycle is a highly conserved and tightly regulated biological system that controls cellular proliferation and differentiation. The cell cycle regulatory proteins, which include the cyclins, the cyclin-dependent kinases (CDKs), and the CDK inhibitors, are critical for the proper temporal and spatial regulation of cellular proliferation. Conversely, alterations in cell cycle regulatory proteins, leading to the loss of normal cell-cycle control, are a hallmark of many cancers, including gastrointestinal cancers. Accordingly, overexpression of CDKs and cyclins and by contrast loss of CDK inhibitors, are all linked to gastrointestinal cancers and are often associated with less favorable prognoses and outcomes. Because of the importance that the cell cycle regulatory proteins play in tumorigenesis, currently there is a broad spectrum of cell-cycle inhibitors under development that, as a group, hold promise as effective cancer treatments. In support of this approach to cancer treatment, the growing availability of molecular diagnostics techniques may help in identifying patients who have driving abnormalities in the cell-cycle machinery and are thus more likely to respond to cell-cycle inhibitors. In this review, we discuss the prevalence of cell-cycle abnormalities in patients with gastrointestinal cancers and provide a preclinical and clinical overview of new agents that target cell-cycle abnormalities with a special emphasis on gastrointestinal cancers.

Tumor suppressors miR-143 and miR-145 and predicted target proteins API5, ERK5, K-RAS, and IRS-1 are differentially expressed in proximal and distal colon

The colon differs regionally in local luminal environment, excretory function, and gene expression. Polycistronic microRNA (miR)-143 and miR-145 are downregulated early in colon cancer. We asked if these microRNAs (miRNAs) might be differentially expressed in the proximal vs. the distal colon, contributing to regional differences in protein expression. Primary transcripts and mature miR-143 and miR-145 were quantified by real-time PCR, putative targets were measured by Western blotting, and DNA methylation was assessed by sequencing bisulfite-treated DNA in proximal and distal normal colonic mucosa as well as colon cancers. Putative targets of these miRNAs were assessed following transfection with miR-143 or miR-145. Mean expression of mature miR-143 and miR-145 was 2.0-fold (P < 0.001) and 1.8-fold (P = 0.03) higher, respectively, in proximal than distal colon. DNA methylation or primary transcript expression of these miRNAs did not differ by location. In agreement with increased expression of miR-143 and miR-145 in proximal colon, predicted targets of these miRNAs, apoptosis inhibitor 5 (API5), ERK5, K-RAS, and insulin receptor substrate 1 (IRS-1), which are cell cycle and survival regulators, were expressed at a lower level in proximal than distal colon. Transfection of HCA-7 colon cancer cells with miR-145 downregulated IRS-1, and transfection of HT-29 colon cancer cells with miR-143 decreased K-RAS and ERK5 expression. In conclusion, miR-143 and miR-145 and the predicted target proteins API5, ERK5, K-RAS, and IRS-1 display regional differences in expression in the colon. We speculate that differences in these tumor suppressors might contribute to regional differences in normal colonic gene expression and modulate site-specific differences in malignant predisposition.

Association between specific KRAS mutations and the clinicopathological characteristics of colorectal tumors

The aim of this study was to investigate the clinicopathological characteristics and distribution by tumor localization of KRAS point mutations in metastatic colorectal cancer. A total of 189 patients diagnosed with colorectal cancer between 2007 and 2014, who were either metastatic at the time of diagnosis or developed metastasis subsequently, were included in this study. KRAS mutation analysis was performed in the primary tumor tissues and KRAS mutations were identified in 47.6% of the patients. There was a high frequency of the p.G13D point mutation in left-colon tumors (P=0.011), while the p.G12D point mutation was more frequent in right-colon tumors (P=0.004). KRAS wild-type frequency (P=0.02) was higher among patients aged <40 years. A comparison of codon 12 and 13 mutations revealed that codon 12 mutations were more common in the >50-year-old group (P=0.03) and codon 13 mutations were more common in the <70-year-old group (P=0.04). KRAS wild-type tumors were localized in the right colon (P=0.005) and tumors with the p.G13D point mutation (P=0.018) were diagnosed at non-metastatic stages. In conclusion, KRAS point mutations in colorectal cancer exhibited a heterogeneous distribution in terms of tumor localization. In addition, the p.G13D point mutation was found to differ from other mutations in several aspects.

RAS mutations: impact on treatment outcome

SUMMARY RAS proteins belong to the MAPK network, an essential pathway for maintenance of normal vital processes such as proliferation and differentiation. RAS mutations are observed in 30–50% of colorectal carcinomas. The MAPK pathway and RAS proteins are part of a complex system that mediate signaling from the EGF receptors (EGFRs). Our review discusses the most recent evidence highlighting the role of KRAS mutations in patients who are offered anti-EGFR therapy. Furthermore, we discuss emerging evidence of the role of other predictive markers such as PI3K, PTEN, BRAF, NRAS, MET, IGFR-1 and p53 in patients who are receiving anti-EGFR therapy.

Poor prognosis of KRAS or BRAF mutant colorectal liver metastasis without microsatellite instability

BACKGROUND

The discovery of practical biomarkers is important to realize personalized medicine for patients with malignant neoplasias, including colorectal cancer (CRC).

PURPOSE

The aim of this study was to determine reliable prognostic biomarkers by the analysis of patients with resectable colorectal liver metastases (CRLM).

METHODS

Genomic DNA was obtained from the CRLM tissues of a cohort of 126 patients with CRLM with curative hepatic resection. The KRAS/BRAF mutation spectrum and microsatellite instability (MSI) status were successfully analyzed in 100 of the 126 CRLM tissues and these findings were examined in relation to the patients' clinical outcomes.

RESULTS

The cohort of 100 CRLM patients consisted of 46 with synchronous and 54 with metachronous liver metastasis. Overall survival and disease-free survival at 5 years were 57.4 and 24.9 %, respectively. MSI analysis revealed that none of the 100 CRLM specimens showed any evidence of MSI. By KRAS/BRAF mutation analysis, the analyzed CRLM patients were divided into 3 groups; KRAS-mutant (KRAS-Mt; n = 27), BRAF-mutant (BRAF-Mt; n = 3), and wild-types of both genes (Wild-type; n = 70). In the survival analysis, both KRAS-Mt and BRAF-Mt patients showed significantly poorer prognoses compared with Wild-type patients. Furthermore, although the population with the BRAF mutation was small, this mutation had a significant negative impact on disease-free survival.

CONCLUSIONS

In this study, all tumors in the cohort of CRLM patients were non-MSI tumors, suggesting MSI cancer in primary CRC would rarely reveal metastatic potential. KRAS and BRAF mutations are suggested to be poor prognostic factors in CRLM. Genetic information has an essential role as a prognostic marker and could contribute to the decisions on treatment strategy for CRLM.

Somatic profiling of the epidermal growth factor receptor pathway in tumors from patients with advanced colorectal cancer treated with chemotherapy ± cetuximab

PURPOSE

To study the somatic molecular profile of the EGF receptor (EGFR) pathway in advanced colorectal cancer, its relationship to prognosis, the site of the primary and metastases, and response to cetuximab.

EXPERIMENTAL DESIGN

We used Sequenom and Pyrosequencing for high-throughput somatic profiling of the EGFR pathway in 1,976 tumors from patients with advanced colorectal cancer from the COIN trial (oxaliplatin and fluoropyrimidine chemotherapy ± cetuximab). Correlations between mutations, clinicopathologic, response, and survival data were carried out.

RESULTS

Sequenom and Pyrosequencing had 99.0% (9,961/10,063) genotype concordance. We identified 13 different KRAS mutations in 42.3% of advanced colorectal cancers, 2 BRAF mutations in 9.0%, 4 NRAS mutations in 3.6%, and 5 PIK3CA mutations in 12.7%. 4.2% of advanced colorectal cancers had microsatellite instability (MSI). KRAS and PIK3CA exon 9, but not exon 20, mutations cooccurred (P = 8.9 × 10(-4)) as did MSI and BRAF mutations (P = 5.3 × 10(-10)). KRAS mutations were associated with right colon cancers (P = 5.2 × 10(-5)) and BRAF mutations with right (P = 7.2 × 10(-5)) and transverse colon (P = 9.8 × 10(-6)) cancers. KRAS mutations were associated with lung-only metastases (P = 2.3 × 10(-4)), BRAF mutations with peritoneal (P = 9.2 × 10(-4)) and nodal-only (P = 3.7 × 10(-5)) metastases, and MSI (BRAF(WT)) with nodal-only metastases (P = 2.9 × 10(-4)). MSI (BRAF(WT)) was associated with worse survival (HR = 1.89, 95% CI 1.30-2.76, P = 8.5 × 10(-4)). No mutations, subsets of mutations, or MSI status were associated with response to cetuximab.

CONCLUSIONS

Our data support a functional cooperation between KRAS and PIK3CA in colorectal tumorigenesis and link somatic profiles to the sites of metastases. MSI was associated with poor prognosis in advanced disease, and no individual somatic profile was associated with response to cetuximab in COIN.

KRAS mutations are associated with specific morphologic features in colon cancer

BACKGROUND

Mutations in the KRAS gene occur at an early stage in the development of colorectal carcinoma. Importantly, KRAS mutation predicts resistance to anti-epidermal growth factor receptor therapy in stage IV disease.

GOALS

The aim of the current study is to correlate histologic features of colon cancer with the presence of KRAS mutations.

STUDY

Tumor tissue from 145 colon cancer resections was tested for KRAS mutations. KRAS mutation status was correlated with demographic and histologic characteristics. Statistical analysis was performed using the Pearson χ2 test and multivariate analysis.

RESULTS

KRAS mutations were present in 55/145 cases (37.9%), consistent with reported rates. KRAS mutations were significantly associated with usual adenocarcinoma morphology (multivariate P=0.014), peritumoral lymphocytic response (χ2, P=0.028; multivariate P=0.017), T3-T4 status (χ2, P=0.012; multivariate P=0.015), right-sided location (multivariate P=0.027), absence of lymphovascular invasion (multivariate P=0.008), and metastases at the time of resection (multivariate P=0.034). No association was found between KRAS mutation status and other factors.

CONCLUSIONS

Specific morphologic features in colon cancer suggest a higher likelihood of the presence of KRAS mutations. These morphologic features overlap partially with those associated with DNA mismatch repair gene mutations. If confirmed, these results may suggest a paradigm for directed KRAS testing.

Integral analysis of p53 and its value as prognostic factor in sporadic colon cancer

BACKGROUND

p53 (encoded by TP53) is involved in DNA damage repair, cell cycle regulation, apoptosis, aging and cellular senescence. TP53 is mutated in around 50% of human cancers. Nevertheless, the consequences of p53 inactivation in colon cancer outcome remain unclear. Recently, a new role of p53 together with CSNK1A1 in colon cancer invasiveness has been described in mice.

METHODS

By combining data on different levels of p53 inactivation, we aimed to predict p53 functionality and to determine its effects on colon cancer outcome. Moreover, survival effects of CSNK1A1 together with p53 were also studied.Eighty-three formalin fixed paraffin embedded colon tumors were enriched for tumor cells using flow sorting, the extracted DNA was used in a custom SNP array to determine chr17p13-11 allelic state; p53 immunostaining, TP53 exons 5, 6, 7 and 8 mutations were determined in combination with mRNA expression analysis on frozen tissue.

RESULTS

Patients with a predicted functional p53 had a better prognosis than patients with non functional p53 (Log Rank p=0.009). Expression of CSNK1A1 modified p53 survival effects. Patients with low CSNK1A1 expression and non-functional p53 had a very poor survival both in the univariate (Log Rank p<0.001) and in the multivariate survival analysis (HR=4.74 95% CI 1.45 - 15.3 p=0.009).

CONCLUSION

The combination of mutational, genomic, protein and downstream transcriptional activity data predicted p53 functionality which is shown to have a prognostic effect on colon cancer patients. This effect was specifically modified by CSKN1A1 expression.

Loss of MUC2 expression predicts disease recurrence and poor outcome in colorectal carcinoma

Clinical staging and histological grading after surgery have been the "gold standard" for predicting prognosis and planning for adjuvant therapy of colorectal cancer (CRC). With the recent development of molecular markers, it has become possible to characterize tumors at the molecular level. This is important for stage II and III CRCs, in which clinicopathological features do not accurately predict heterogeneity, e.g., in their tumor response to adjuvant therapy. In the present study, archival samples from 141 patients with stage I, II, III, or IV CRC treated during 1981-1990 at Turku University Hospital (Finland) were used (as microarray blocks) to analyze MUC2 expression by immunohistochemistry. Altogether, 49.7 % of all tumors were positive for MUC2. There was no significant correlation between MUC2 expression and age (P < 0.499), tumor invasion (P < 0.127), tumor staging (P < 0.470), histological grade (P < 0.706), lymph node involvement (P < 0.854), or tumor metastasis (P < 0.586). However, loss of MUC2 expression was significantly associated with disease recurrence (P < 0.031), tumor localization (P < 0.048), and with borderline significance with gender (P < 0.085). In univariate (Kaplan-Meier) survival analysis, positive MUC2 significantly predicted longer disease-free survival (DFS) and disease-specific survival (DSS) as well. However, in multivariate (Cox) survival analysis, MUC2 lost its power as an independent predictor of DFS and DSS. Our results implicate the value of MUC2 expression in predicting disease recurrence and long-term survival in CRC.

Missense mutations in MLH1, MSH2, KRAS, and APC genes in colorectal cancer patients in Malaysia

BACKGROUND

Colorectal cancer (CRC) is the third most common cancer worldwide with approximately 1 million cases diagnosed annually. In Malaysia, CRC is the second most common cancer in women and ranked first in men. The underlying cause of CRC remains unknown.

AIMS

The aim of this study was to analyze the mutations in genes involved in CRC including MLH1, MSH2, KRAS, and APC genes.

METHODS

A total of 76 patients were recruited. We used the polymerase chain reaction-denaturing high-performance liquid chromatography for the detection of mutations in the mismatch repair (MMR) and APC genes and the PCR single-strand conformation polymorphism for screening of the KRAS gene mutations.

RESULTS

We identified 17 types of missense mutations in 38 out of 76 patients in our patients. Nine mutations were identified in the APC gene, five mutations were detected in the KRAS gene, and two mutations were identified in the MSH2 gene. Only one mutation was identified in MLH1. Out of these 17 mutations, eight mutations (47 %) were predicted to be pathogenic. Seven patients were identified with multiple mutations (3: MSH2 and KRAS, 1: KRAS and APC, 1: MLH1 and APC, 2: APC and APC).

CONCLUSIONS

We have established the PCR-DHPLC and PCR-SSCP for screening of mutations in CRC patients. This study has given a snapshot of the spectrum of mutations in the four genes that were analyzed. Mutation screening in patients and their family members will help in the early detection of CRC and hence will reduce mortality due to CRC.

Expression of cell cycle regulators p21 and p27 as predictors of disease outcome in colorectal carcinoma

BACKGROUND

Recent studies suggest that aberrations in cell cycle checkpoint controllers are a common feature in human malignancies and predict prognosis independent of stage.

OBJECTIVES

This study correlated two cell cycle regulators (p27 and p21) with clinical and pathological variables in colorectal cancer (CRC) patients to assess their role as prognostic factors.

PATIENTS AND METHODS

A series of 65 CRC patients were analyzed for p27 and p21 expression in their tumors using immunohistochemistry.

RESULTS

Forty-six percent of tumors showed positive nuclear p27 expression, whereas 72% of cases were completely p21 negative. There were no significant correlations between p27 and p21 expression and gender, age, lymph node involvement, stage, and grade. However, p27 (but not p21) expression revealed highly significant correlation with tumor location (p < 0.01), depth of invasion (p < 0.03), and lympho-vascular invasion (p < 0.02). Tumors with high p27 expression showed a higher recurrence rate than tumors with no expression (p < 0.03). In Kaplan-Meier survival analysis, there was a significant (p = 0.046) difference in disease-free survival (DFS) between p27-positive and p27-negative tumors in favor of the latter. p21 did not show any predictive value of DFS (p < 0.7). Neither p27 nor p21 did predict disease-specific survival (DSS) in Kaplan-Meier analysis, but DSS time was much shorter for p27-positive tumors. In multivariate (Cox) model, p27 lost its value as independent predictor of DFS, and none of the covariates were independent predictors of DSS.

CONCLUSION

p27 expression seems to be more powerful than p21 expression in providing useful prognostic information in CRC, particularly in predicting the patients at high risk for recurrent disease. Larger cohort and longer follow-up are needed to fully elucidate the value of p27 (and p21) as independent predictors of disease outcome.

Influence of anatomical subsite on the incidence of microsatellite instability, and KRAS and BRAF mutation rates in patients with colon carcinoma

There is a growing amount of data supporting the concept that cancers originating from the proximal and distal colon are distinct clinicopathological entities. The incidence of MSI and BRAF mutation is strongly associated with right sided tumor location, whereas there are conflicting results for KRAS mutation rates. However, to date, no data exist whether and to what extent defined colonic subsites influence MSI status, KRAS and BRAF mutation rates. We selected primary colon cancer from 171 patients operated on at our institution between 2007 and 2010. BRAF, KRAS mutation rates and microsatellite instability were determined and correlated with clinicopathological features and tumor location. MSI-h cancers were significantly associated with poor histological grade but a lower rate of distant metastases. KRAS-mutated tumors were linked to lower T-stage and better differentiation. Colon carcinomas with BRAF mutation were significantly associated with distant metastatic spread and poor histological grade. Furthermore, we found that MSI-h status, KRAS and BRAF mutation rates varied remarkably among the colonic subsites irrespective of right- and left-sided origin, respectively. The results of the current study provide further evidence that a simple classification into right- and left-sided colon carcinoma does not represent the complexity of this tumor entity.

Right-side and left-side colon cancer follow different pathways to relapse

There is growing evidence that cancer of the ascending (right-side) colon is different from cancer of the descending (left-side) colon at the molecular level. Using microarray data from 102 right-side colon carcinomas and 95 left-side colon carcinomas we show that different pathways dominate progression to relapse in right-side and left-side colon cancer. Right-side tumors at a high risk for relapse exhibit elevated expression of cell cycle control genes and elevated Wnt signaling. On the other hand, relapse-prone left-side tumors show elevated expression of genes that promote stromal expansion and reduced expression of tumor suppressor genes that initiate Wnt signaling. Single gene prognostic biomarkers are found separately for right-side and left-side disease. In left-side tumors with low expression levels of NADPH oxidase 4 (NOX4) the 5-yr relapse-free survival probability is 0.89 95% CI (0.80-0.99), and in tumors with elevated NOX4 expression the probability is 0.51 95% CI (0.37-0.70). Right-side tumors with elevated expression levels of caudal type homeobox 2 (CDX2) have a 5-yr relapse-free survival probability of 0.88 95% CI (0.80-0.96), and those with low CDX2 expression have a corresponding probability of 0.39 95% CI (0.15-0.78). Both NOX4 and CDX2 are much less prognostic on the opposite sides. This newly identified role of NOX4 in colon cancer is further investigated using the SW620 lymph node metastasis colon adenocarcinoma cell line and RNA interference. We show that NOX4 is expressed in the SW620 cell line and that application of NOX4 siRNA causes a significant reduction in reactive oxidative species production.

A novel mutant-enriched liquidchip technology for the qualitative detection of somatic mutations in KRAS gene from both serum and tissue samples

BACKGROUND

Somatic mutations in the KRAS gene have been reported to confer drug resistance to epidermal growth factor receptor tyrosine kinase inhibitors and some monoclonal antibodies. However, current DNA mutation detection technologies are primarily DNA sequencing-based and not high throughput, nor sensitive enough to meet clinical needs.

METHODS

A mutant-enriched PCR method was designed by introducing a unique restriction enzyme site to the PCR product. This allowed the wild-type KRAS sequence to be selectively removed by restriction enzyme digestion before application to the Luminex liquidchip system.

RESULTS

A total of 100 copies of mutant KRAS DNA fragment mixed with 1x10(5) copies of the wild-type KRAS DNA could be detected to achieve a sensitivity of 0.1%. This technology is currently used for clinical testing of KRAS somatic mutations for the purpose of pharmacogenomic evaluation. Serum samples from 109 patients with non-small cell lung cancer were tested and 34 mutations were detected (34/109). The formalin-fixed and paraffin-embedded samples from 60 patients with colorectal cancer were tested and 19 mutations were detected (19/60).

CONCLUSIONS

A novel, qualitative, sensitive, reliable and high throughput liquidchip technology has been developed for detecting KRAS mutations using clinical serum and formalin-fixed and paraffin-embedded samples.

Location-related differences in sporadic microsatellite unstable colorectal cancer

BACKGROUND

Microsatellite unstable CRC is associated with female gender, large tumours, and poor differentiation. However, there are few reports about the characteristics and differences of sporadic microsatellite unstable CRC based on tumour location.

AIMS

Site-specific heterogeneity of sporadic microsatellite unstable colorectal cancer (CRC) based on location was elucidated.

METHODS

We enrolled 164 CRC patients with high-frequency microsatellite instability (MSI-H) from the prospective database of 2686 consecutive CRC patients who underwent surgical resection. We analysed microsatellite instability (MSI) and expression of mismatch repair (MMR) proteins (MLH1, MSH2, and MSH6).

RESULTS

Among the 164 MSI-H CRC, 105 (64.0%) were located in the proximal colon and 59 (36.0%) were located in the distal colon. The proximal MSI-H CRC was predominantly in female (p=0.014), had a more aggressive differentiation (p=0.001), was of advanced stage (p=0.035), and had a frequent loss of MLH1 expression (p=0.005) compared to the distal MSI-H CRC.

CONCLUSION

There were different clinicopathologic characteristics and MMR protein expression between proximal and distal MSI-H CRC. These findings suggest that the underlying carcinogenic pathway or molecular background differs according to location, despite being microsatellite unstable CRC.

A review of the most promising biomarkers in colorectal cancer: one step closer to targeted therapy

Rapidly growing insights into the molecular biology of colorectal cancer (CRC) and recent developments in gene sequencing and molecular diagnostics have led to high expectations for the identification of molecular markers to be used in optimized and tailored treatment regimens. However, many of the published data on molecular biomarkers are contradictory in their findings and the current reality is that no molecular marker, other than the KRAS gene in the case of epidermal growth factor receptor (EGFR)- targeted therapy for metastatic disease, has made it into clinical practice. Many markers investigated suffer from technical shortcomings, resulting from lack of quantitative techniques to capture the impact of the molecular alteration. This understanding has recently led to the more comprehensive approaches of global gene expression profiling or genome-wide analysis to determine prognostic and predictive signatures in tumors. In this review, an update of the most recent data on promising biological prognostic and/or predictive markers, including microsatellite instability, epidermal growth factor receptor, KRAS, BRAF, CpG island methylator phenotype, cytotoxic T lymphocytes, forkhead box P3-positive T cells, receptor for hyaluronic acid-mediated motility, phosphatase and tensin homolog, and T-cell originated protein kinase, in patients with CRC is provided.

MMP-9 (gelatinase B) expression is associated with disease-free survival and disease-specific survival in colorectal cancer patients

Extracellular matrix degradation is required for invasion and metastasis formation in colorectal carcinoma (CRC), therefore, we have examined matrix metalloproteinases MMP-9 expression in tumors from patients with CRC. The study comprises of 360 patients who underwent bowel resection for stage II, III, IV tumors. Paraffin-embedded CRC tissue samples were used for immunohistochemical staining. Negative MMP-9 expression levels correlated with longer survival time as evaluated by disease-free survival and disease-specific survival (p =.023, p =.006). In multivariate survival (Cox) analysis, MMP9 was a significant independent predictor of DFS (p =.014), but not of DSS, which was independently predicted by disease recurrence, stage and localization. The detection of MMP-9 expression may be valuable in finding patients who are at high risk of developing disease recurrence.

Comparison of 17,641 patients with right- and left-sided colon cancer: differences in epidemiology, perioperative course, histology, and survival

PURPOSE

There is a growing amount of data suggesting that carcinomas of the right and left colon should be considered as different tumor entities. Using the data and analysis compiled in the German multicentered study "Colon/Rectum Cancer," we aimed to clarify whether the existing differences influence clinical and histological parameters, the perioperative course, and the survival of patients with right- vs left-sided colon cancer.

METHODS

During a 3-year period data on all patients with colon cancer were evaluated. Right- and left-sided cancers were compared regarding the following parameters: demographic factors, comorbidities, and histology. For patients who underwent elective surgery with curative intent, the perioperative course and survival were also analyzed.

RESULTS

A total of 17,641 patients with colon carcinomas were included; 12,719 underwent curative surgery. Patients with right-sided colon cancer were significantly older, and predominantly women with a higher rate of comorbidities. Mortality was significantly higher for this group. Final pathology revealed a higher percentage of poorly differentiated and locally advanced tumors. Rate of synchronous distant metastases was comparable. However, hepatic and pulmonary metastases were more frequently found in left-sided, peritoneal carcinomatosis in right-sided carcinomas. Survival was significantly worse in patients with right-sided carcinomas on an adjusted multivariate model (odds ratio, 1.12).

CONCLUSIONS

We found that right- and left-sided colon cancers are significantly different regarding epidemiological, clinical, and histological parameters. Patients with right-sided colon cancers have a worse prognosis. These discrepancies may be caused by genetic differences that account for distinct carcinogenesis and biological behavior. The impact of these findings on screening and therapy remains to be defined.

PLA2 (group IIA phospholipase A2) as a prognostic determinant in stage II colorectal carcinoma

BACKGROUND

Approximately 30% of all colorectal cancer (CRC) patients are diagnosed with stage II disease. Adjuvant therapy is not widely recommended. However, it is well established that a subgroup of patients with stage II are at high risk for recurrence within their lifetime and should be considered for adjuvant chemotherapy. The present work was designed to assess the value of group IIA phospholipase A2 (PLA2) as a predictor of disease outcome in stage II CRC patients with long-term follow-up.

PATIENTS AND METHODS

The present study comprises a series of 116 patients who underwent bowel resection for stage II CRC during 1981-1990 at Turku University Hospital. Archival paraffin-embedded CRC tissue samples were used to prepare tissue microarray blocks for immunohistochemical staining with PLA2.

RESULTS

Fifty-five percent of all tumors were positive for PLA2. There was no significant correlation between PLA2 expression and age, sex, depth of invasion and lymph node status. In Kaplan-Meier survival analysis, there was a significant (P = 0.010) difference in disease-free survival (DFS) between patients with negative tumors (longer DFS) and those with positive tumors. The same was true with disease-specific survival (DSS), patients with PLA2-negative tumors living significantly longer (P = 0.025). In multivariate (Cox) survival analysis, however, PLA2 was not an independent predictor of DFS or DSS. In subgroup analysis, the right-sided tumors with negative PLA2 staining had remarkably better prognosis (P = 0.010) than PLA2-positive left-sided tumors.

CONCLUSIONS

Quantification of PLA2 expression seems to provide valuable prognostic information in stage II CRC, particularly in selecting the patients at high risk for recurrent disease who might benefit from adjuvant therapy.

K-ras mutations and benefit from cetuximab in advanced colorectal cancer

BACKGROUND

Treatment with cetuximab, a monoclonal antibody directed against the epidermal growth factor receptor, improves overall and progression-free survival and preserves the quality of life in patients with colorectal cancer that has not responded to chemotherapy. The mutation status of the K-ras gene in the tumor may affect the response to cetuximab and have treatment-independent prognostic value.

METHODS

We analyzed tumor samples, obtained from 394 of 572 patients (68.9%) with colorectal cancer who were randomly assigned to receive cetuximab plus best supportive care or best supportive care alone, to look for activating mutations in exon 2 of the K-ras gene. We assessed whether the mutation status of the K-ras gene was associated with survival in the cetuximab and supportive-care groups.

RESULTS

Of the tumors evaluated for K-ras mutations, 42.3% had at least one mutation in exon 2 of the gene. The effectiveness of cetuximab was significantly associated with K-ras mutation status (P=0.01 and P<0.001 for the interaction of K-ras mutation status with overall survival and progression-free survival, respectively). In patients with wild-type K-ras tumors, treatment with cetuximab as compared with supportive care alone significantly improved overall survival (median, 9.5 vs. 4.8 months; hazard ratio for death, 0.55; 95% confidence interval [CI], 0.41 to 0.74; P<0.001) and progression-free survival (median, 3.7 months vs. 1.9 months; hazard ratio for progression or death, 0.40; 95% CI, 0.30 to 0.54; P<0.001). Among patients with mutated K-ras tumors, there was no significant difference between those who were treated with cetuximab and those who received supportive care alone with respect to overall survival (hazard ratio, 0.98; P=0.89) or progression-free survival (hazard ratio, 0.99; P=0.96). In the group of patients receiving best supportive care alone, the mutation status of the K-ras gene was not significantly associated with overall survival (hazard ratio for death, 1.01; P=0.97).

CONCLUSIONS

Patients with a colorectal tumor bearing mutated K-ras did not benefit from cetuximab, whereas patients with a tumor bearing wild-type K-ras did benefit from cetuximab. The mutation status of the K-ras gene had no influence on survival among patients treated with best supportive care alone. (ClinicalTrials.gov number, NCT00079066.)

Oncogenic K-ras promotes early carcinogenesis in the mouse proximal colon

Oncogenic K-ras mutations are frequently observed in colon cancers and contribute to transformed growth. Oncogenic K-ras is detected in aberrant crypt foci (ACF), precancerous colonic lesions, demonstrating that acquisition of a K-ras mutation is an early event in colon carcinogenesis. Here, we investigate the role of oncogenic K-ras in neoplastic initiation and progression. Transgenic mice in which an oncogenic K-ras(G12D) allele is activated in the colonic epithelium by sporadic recombination (K-rasLA2 mice) develop spontaneous ACF that are morphologically indistinguishable from those induced by the colon carcinogen azoxymethane (AOM). Similar neoplastic changes involving the entire colon are induced in transgenic mice constitutively expressing K-ras(G12D) throughout the colon (LSL-K-ras(G12D)/Villin-Cre mice). However, the biochemistry and fate of K-ras-induced lesions differ depending upon their location within the colon in these mice. In the proximal colon, K-ras(G12D) induces increased expression of procarcinogenic protein kinase C beta II (PKC beta II), activation of the MEK/ERK signaling axis and increased epithelial cell proliferation. In contrast, in the distal colon, K-ras(G12D) inhibits expression of procarcinogenic PKC beta II and induces apoptosis. Treatment of K-rasLA2 mice with AOM leads to neoplastic progression of small ACF to large, dysplastic microadenomas in the proximal, but not the distal colon. Thus, oncogenic K-ras functions differently in the proximal and distal colon of mice, inducing ACF capable of neoplastic progression in the proximal colon, and ACF with little or no potential for progression in the distal colon. Our data indicate that acquisition of a K-ras mutation is an initiating neoplastic event in proximal colon cancer development in mice.

Mutations in the RAS-MAPK, PI(3)K (phosphatidylinositol-3-OH kinase) signaling network correlate with poor survival in a population-based series of colon cancers

The RAS-MAPK, PI (3)K signaling pathways form a network that play a central role in tumorigenesis. The BRAF, KRAS and PI3KCA genes code 3 partners of this network and have been found to be activated by mutation in colorectal cancer; these mutations lead to unrestricted cell growth. We evaluated the clinicopathological features and the prognosis of patients with activated-network colon cancers in a population-based study. A total of 586 colon adenocarcinomas were evaluated using sequencing for mutations of KRAS and PI3KCA, and allelic discrimination for mutation of BRAF. Clinicopathological characteristics were correlated to the risk of bearing a mutation of the network using logistic regression. Three-year survival rates were compared with the Log rank test. A multivariate survival analysis using the Cox model was performed. After adjustment for age and microsatellite instability, activation of the network by mutation of at least 1 of the 3 genes was significantly associated with female sex (p = 0.02) and proximal location (p < 0.001). Lower levels of 3-year survival were associated with activation of the network by mutation of at least 1 of the 3 genes (59.4 and 69.4%, respectively; p = 0.009). These results remained significant in a multivariate analysis adjusted for sex, age, location, stage and microsatellite instability (HR = 1.48; CI CI(95%) = [1.07-2.04]). Our study is the first report to underline the potential role of RAS-MAPK, PI (3)K network mutations on survival in colon cancers. Because of the role of this signaling network on anticancer agents, the evaluation of its mutations could have clinical implications.

Analysis of molecular alterations in left- and right-sided colorectal carcinomas reveals distinct pathways of carcinogenesis: proposal for new molecular profile of colorectal carcinomas

To clarify distinct genetic profiles of colorectal cancers based on tumor location (left- and right-sided), we evaluated the status of loss of heterozygosity (LOH), CpG islands methylation phenotype (CIMP), microsatellite instability (MSI), and mutations of p53, Ki-ras, and APC genes in 119 colorectal cancers. Statuses of LOH (at 5q, 8p, 17p, 18q, and 22q), MSI, and CIMP (MINT1, MINT2, MINT31, MLH-1, MGMT, p14, p16, and RASSF1A) were determined using microsatellite polymerase chain reaction and methylation-specific polymerase chain reaction coupled with a crypt isolation method, respectively. In addition, mutations of p53, Ki-ras, and APC genes were also examined. LOH, MSI, and CIMP status allowed us to classify samples into two groups: low or negative and high or positive. Whereas the frequency of p53 mutations in the LOH-high status was significantly higher in left-sided cancers than in right-sided cancers, CIMP-high in the LOH-high status and MSI-positive status were more frequently found in right-sided cancers compared with left-sided cancers. Finally, location-specific methylated loci were seen in colorectal cancers: type I (dominant in right-sided cancer) and type II (common in both segments of cancer). Our data confirm that distinct molecular pathways to colorectal cancer dominate in the left and right sides of the bowel.

Effect of concomitant polyethylene glycol and celecoxib on colonic aberrant crypt foci and tumors in F344 rats

We investigated whether celecoxib augments the protective effect of polyethylene glycol (PEG) on colonic aberrant crypt foci (ACF) and tumor formation in F344 rats treated with azoxymethane (AOM). Three groups of rats received AOM: I (AOM alone), II (PEG), and III (PEG/celecoxib). PEG reduced the mean number of total ACF per colon from 190 to 141 (P < 0.05; 26% reduction) and > or = 4-crypt ACF from 95 to 58 (P < 0.01; 39%). Group III rats had a greater proportion of their ACF distally; whereas transverse colon ACF were reduced approximately 50%, distal ACF were reduced by only approximately 8% (P < 0.05). Of 13 large bowel tumors, 8 were in Group I, 4 in Group II, and 1 in Group III rats (P = 0.02). Thus in AOM-treated rats celecoxib appeared to enhance the PEG-induced reduction in colonic tumor formation, and in transverse but not distal or whole-colon ACF.