Right-sided Colorectal Carcinoma Research Articles

Colorectal carcinoma-induced iron deficiency anemia: A literature review and a case scenario

Colorectal carcinoma (CRC) is among the leading cancers worldwide and a major cause of cancer-related mortality. Iron deficiency anemia (IDA), resulting from inadequate iron for hemoglobin production, has been increasingly linked to CRC, often leading to misdiagnosis. This study reviews the clinicopathological associations of IDA in the context of colorectal cancer, using the medical records of a septuagenarian diagnosed with both conditions as a case study. Employing the Problem-Intervention-Comparison-Outcome model, we searched for “colorectal carcinoma” and “iron deficiency anemia” as keywords. CRC ranks among the top five cancers of global health importance, with socioeconomic factors, sedentary lifestyles, and dietary choices significantly influencing both conditions. Notably, IDA is particularly associated with the right-sided CRC in individuals over 40. Upregulation of interleukin-6 in CRC cells stimulates hepcidin release, which mediates anemia of chronic disorders and IDA. The case revealed right-sided signet ring cell CRC, microcytic hypochromic anemia, bone marrow metastasis, and low serum iron and ferritin levels. This study highlights the need for increased suspicion of CRC in middle-aged and elderly patients presenting with recurrent IDA. Regular screening is essential for the early detection and improved treatment outcomes. While colonoscopy is the gold standard for prevention, its effectiveness in detecting early molecular links between neoplasia and chronic inflammation is limited. There is also no consensus on surveillance protocols, and many gastroenterologists do not adhere to recommended biopsy sampling practices. In conclusion, this study advocates for including complete blood count and iron studies as essential tests in guidelines for screening and diagnosis for CRC-related IDA to enhance diagnostic practices.

Comparison of Post-Operative Outcomes of Right Colectomy between Crohn's Disease and Adenocarcinoma of the Right Colon: A Retrospective Cohort Study.

(1) Background: Crohn's disease (CD) and right-sided colorectal-carcinoma (CRC) are two common indications for right colectomies. Many studies have tried to identify risk factors associated with post-operative complications for both CD and CRC. However, data directly comparing the outcomes of the two are sparse. This study aims to compare the 30-day post-operative outcome after a right colectomy for CD versus CRC. Its secondary aim is to identify the factors associated with these outcomes for each group. (2) Methods: A retrospective cohort study of 123 patients who underwent a right colectomy for CD or CRC in a single institution between March 2011 and March 2016. (3) Results: There were no significant differences between the groups when comparing the overall complication rate, the median Clavien-Dindo score, reoperation rates and the length of hospitalization. The leak rate was higher in the Crohn's group (13.95% (6/43) vs. 3.75% (3/80)), p = 0.049), although the stoma rate was the same (4/43 9.5%; 7/80 9.9%). (4) Conclusions: This study has shown that post-operative complication rate is similar for right colectomy in CD and CRC. However, Crohn's disease patients did have a higher leak rate.

PD-L1 Expression in Colorectal Carcinoma Correlates with the Immune Microenvironment.

Colorectal carcinoma (CRC) is a common malignancy, with its diverse clinical, pathological, and molecular features. The immune microenvironment of a tumor comprises of interplay between various cells and molecules, and has a significant role in deciding the tumor behavior and overall prognosis. PD-L1 (programmed cell death ligand-1) has been implicated in the regulation of the tumor immune microenvironment (TIME). There is limited data regarding the correlation of PD-L1 expression with immune cell profile in CRCs, especially in the Indian setting. The study aimed to assess the PD-L1 expression in CRC tumor cells and its association with TIME, mismatch repair (MMR), and various other clinicopathological parameters. This is a hospital-based, cross-sectional observational study. PD-L1 expression was assessed at the protein level by immunohistochemistry and mRNA level by qRT-PCR. Immune cell markers (CD4, CD8, CD20, FOXP3, and CD163) were interpreted using the ImageJ Fiji platform. Of the 104 cases, 21% were PD-L1 positive and were more common in right-sided CRCs. PD-L1 positive cases showed significantly higher concentrations of all T-cell subsets (CD4+ , CD8+ , and FOXP3+), CD20+ B-cells, and CD163+ macrophages were noted. No statistical significance was seen between PD-L1 expression with clinical profile, pathological subtype, grade or stage, mismatch repair status (proficient vs deficient), and survival. The present study showed a relatively lower frequency of PD-L1 in CRC from the Eastern Indian cohort. The immune cell concentration in the present study was calculated using image analysis-based objectivised methods. Significant correlation of PD-L1 expression in tumor cells with the tumor-infiltrating immune cells indicated its crucial role in the pathobiology of CRC especially by regulating the TIME. Considering the therapeutic implication of PD-L1 in various malignancies, it may be one of the crucial therapeutic targets in a proportion of cases.

Comprehensive genomic profiling of small bowel adenocarcinoma by tissue and plasma biopsy

Small bowel adenocarcinoma (SBA) is a rare and aggressive malignancy with limited treatment options and poor prognosis. The molecular landscape and immunological characteristics of SBA are poorly understood. Here, we performed comprehensive mutation profiling of tissue and plasma biopsies from 143 and 42 patients with SBA. Analysis showed that SBA had a distinct mutation spectrum from left- and right-sided colorectal carcinoma. Plasma biopsy had high concordance with tissue biopsy for single nucleotide variants and structural variants, but low concordance for copy number variations, which showed that plasma biopsy can be an alternative to tissue biopsy. Moreover, we analyzed the association of TMB with clinical and molecular features, and found that TMB was significantly higher in tumors with DNA damage response alterations. Our findings provide valuable insights into the molecular and immunological features of SBA and demonstrate the potential of plasma biopsy as a non-invasive method for SBA diagnosis and treatment.

Laterality influence on gene expression of DNA damage repair in colorectal cancer

Colorectal carcinoma (CRC) is the third most common malignancy worldwide, and second in number of deaths in the world. The molecular pathogenesis of CRC is heterogeneous and can affect several genes. Moreover, genomic instability is recognized as an important part of CRC carcinogenesis and is tightly connected to DNA damage response. DNA damage repair (DDR) pathways are intrinsically associated with cancer development and establishment. Traditionally, CRC is considered as one coherent disease, however, new evidence shows that left and right-sided CRC present differences observed in clinical settings, as well as in pre-clinical studies. Therefore, this study aimed to investigate the impact of DDR transcriptional profiles on survival in different sublocations of the colon and rectum using Cox regression, survival analysis and differential gene expression. Right side colon (RSC) has DDR genes’ expression associated only with higher risk of death, while left side colon (LSC) and Rectum have most genes’ expression associated with lower risk. The pattern is the same with survival analysis. All significant DDR genes had lower expression associated with better survival in RSC, as opposed to LSC and Rectum. Our results demonstrate that RSC is distinctively different from LSC and Rectum. LSC and Rectum have similar DDR expression profiles.

SATB1 Expression of Colorectal Adenomatous Polyps is Higher than that of Colorectal Carcinomas.

"Special AT-rich sequence-binding protein-1" (SATB1) is a global genome organizer and is found to have effects on carcinogenesis and progression of various malignancies including colorectal carcinoma (CRC). We aimed to investigate the expression of SATB1 in CRC and colorectal adenomatous polyps (CAP), the correlation between clinicopathologic parameters, and overall survival. We examined 227 CRCs and 129 CAPs. SATB1 protein expression was evaluated by immunohistochemistry. We found higher SATB1 expression in adenomatous epithelium than in CRC tissues (55.0% vs. 42.7%, respectively) (P<0.05). None of the adjacent normal colorectal mucosa stained positive in CRC cases, and only one of the adjacent normal mucosa of the CAP cases was positive. SATB1 expression of left-sided CRC was higher than that of right-sided CRC (46.3% vs. 28.6%, respectively) (P<0.05), and SATB1 expression of conventional adenocarcinomas was higher than that of mucinous carcinomas (45.5% vs. 6.3%, respectively) (P<0.05). SATB1 expression was higher in CAPs consisting of high-grade dysplasia than in polyps with low-grade dysplasia (77.8% vs. 51.4%) (P<0.05). SATB1 expression did not correlate with patients' overall survival. In conclusion, due to the higher expression of SATB1 in CAP than in CRC, we think SATB1 may have a role in the early stages of carcinogenesis of CRCs. This is the first study investigating SATB1 expression in CAPs. Besides this is the first report that shows different SATB1 expressions in conventional colorectal adenocarcinoma and mucinous carcinoma, and also in right-sided and left-sided CRC. Our results, with supporting new studies, can provide SATB1 as a possible candidate for targeted therapy for CRC patients.

The Case Files

Figure: Image A.FigureFigureA 41-year-old woman presented to the emergency department with abdominal pain, noting multiple episodes over the past year of intermittent right upper quadrant pain that she described as “achy” and “fullness.” These episodes occurred sporadically with no identifiable exacerbating factors. Associated symptoms included a 20-pound unintentional weight loss over two months with occasional nausea and vomiting. She was a former smoker of 10-pack years and had stopped two months prior to arrival, and she reported drinking two to three glasses of wine a week. She did not have a primary care physician. Her vital signs on arrival were a temperature of 97.7°F, blood pressure of 132/97 mm Hg, heart rate of 98 bpm, 99% pulse ox on room air, respirations of 18 bpm, and weight of 76 kg. A physical exam revealed mild tenderness to deep palpation in the RUQ with appreciable hepatomegaly. Laboratory values were remarkable for a hemoglobin of 12.7 g/dL, mean corpuscular volume of 92, gamma-glutamyl transferase of 382 (9-48 U/L), total bilirubin of 0.6, alkaline phosphatase of 205 (44-147), aspartate aminotransferase of 55 U/L (10-37 U/L), alanine aminotransferase of 33 U/L (8-37 U/L). She was hemoccult-positive on rectal exam. Ultrasound showed multiple lobulated ill-defined masses throughout the liver. (Images A and B.) A CT abdomen/pelvis showed multiple heterogeneously enhancing irregular hepatic masses, with the largest measuring 10.6 x 10.1 x 11.1 cm. (Images C and D.) She was admitted for further evaluation. High Mortality Colorectal carcinoma is a common and lethal disease with around 140,000 cases diagnosed annually in the United States. (UpToDate, May 2, 2018; http://bit.ly/2IPlAS5.) About 56,000 patients die of the disease. Clinical research has shown that patients with a primary care physician have better management of chronic disease, access to preventive care, including cancer screenings, and chronic care of a multitude of medical problems. Advanced cases, like our patient's demonstrated, commonly present with iron-deficient anemia, rectal bleeding, abdominal pain, change in bowel habits, and sometimes an intestinal obstruction or perforation. A study of 388 patients diagnosed with colorectal carcinoma from 2011-2014 found the most common symptoms leading to a diagnostic colonoscopy to be rectal bleeding (37%), abdominal pain (34%), and anemia (23%). (UpToDate, May 2, 2018; http://bit.ly/2IPlAS5.) Clinical manifestations will differ depending on the location of the tumor. A change in bowel habits is more common in left-sided colorectal carcinoma, as is hematochezia. Iron-deficient anemia has been found to be more common in right-sided colorectal carcinoma. (UpToDate, May 2, 2018, http://bit.ly/2IPlAS5; Clin Colorectal Cancer 2016;15[1]:67; http://bit.ly/2KDxe7F.)Figure: Image B.Figure: Image C.The goal of laboratory evaluation is to assess patients' organ function for potential diagnostic and therapeutic procedures, as well as tumor burden. A baseline carcinoembryonic antigen carries a prognostic value. Patients with highly elevated values are associated with more advanced disease. (Anticancer Res 2001;21[4B]:3031.) Colorectal carcinoma metastases are most commonly found in the liver and the lung. Chemotherapy and radiation therapy following surgical resection of the primary tumor, when indicated, remain the mainstay of adjuvant therapy. Approximately 20 percent of patients are diagnosed with metastatic disease at their initial presentation. (UpToDate, May 2, 2018; http://bit.ly/2IPlAS5.) Our patient's colonoscopy showed an ulcerated sigmoid mass. The tumor marker carbohydrate Ag 19-9 was 670 U/mL (0-35). The confirmed diagnosis of metastatic adenocarcinoma with primary colorectal carcinoma was made based on subsequent CT-guided biopsy of the liver, followed by pathological report and a biopsy at the ulcerated sigmoid mass showing high-grade dysplasia. Given the extent and bilobar nature of the metastases, our patient's best option was to start systemic chemotherapy, followed by fully restaging after 12 cycles to determine if she would benefit from liver-directed therapy.Figure: Image D.

PD-018 - Comparing survival in left-sided and right-sided colorectal carcinoma: A Belgian population-based study

PD-018 - Comparing survival in left-sided and right-sided colorectal carcinoma: A Belgian population-based study

Exploratory analysis of left- versus right-sided colorectal carcinoma in RAISE: A randomized, double-blind, phase 3 trial of ramucirumab (RAM) + FOLFIRI versus placebo (PBO) + FOLFIRI.

668 Background: Ramucirumab is a human IgG1 monoclonal antibody antagonist of VEGFR-2. Overall survival (OS) and progression-free survival (PFS) in 2nd line FOLFIRI based treatment for metastatic colorectal cancer (mCRC) were improved with RAM therapy versus PBO in the RAISE trial. Recent work suggests mCRC primary tumor location is both prognostic and predictive; with improved OS and therapy-specific sensitivity observed in left (L)- vs right (R)-sided tumors. Given these findings, the RAISE trial data was subjected to post-hoc analysis to determine if sidedness influenced RAM efficacy. Methods: Primary tumor site was obtained. L-CRC was defined as the splenic flexure, descending and sigmoid colon, and rectum, while R-CRC included transverse, ascending colon and cecum. OS/PFS in L and R subgroups were analyzed via Kaplan-Meier method and unstratified log-rank test (treatments within subgroup), unstratified Cox proportional hazards model (estimate hazard ratio [HR] and 95% CI), and Wald test (treatment-by-subgroup interaction). Results: Tumor location was available for 1012/1072 (94%) patients, 699 L- and 313 R-CRC. Baseline characteristics were balanced between arms. RAM treatment enhanced L-CRC median OS by 2.5 mo (median 14.5 vs 12.0 mo) with a HR (95% CI) = 0.807 (0.675, 0.965), P = 0.019; compared to a 1.1 mo increase in median OS in R-CRC vs PBO (12.7 vs 11.6) with a HR (95% CI) = 0.971 (0.750, 1.258), P = 0.823; and, RAM enhanced L-CRC median PFS by 1.6 mo (6.0 vs 4.4 mo) and HR (95% CI) = 0.776 (0.664, 0.906), P = 0.001 compared to a 1.1 mo increase in median PFS R-CRC vs PBO (5.6 vs 4.5) with a HR (95% CI) = 0.855 (0.674, 1.084), P = 0.197. The treatment-by-subgroup interaction for both OS and PFS was not significant ( P = 0.276, 0.578, respectively). Conclusions: Despite L-CRC patients having longer OS/PFS and a seemingly stronger RAM treatment effect than R-CRC, the non-significant interaction test cannot verify sidedness as being predictive of RAM efficacy. The current study confirms ramucirumab benefits mCRC patients regardless primary tumor location. Clinical trial information: NCT01183780.

Clinicopathological comparison of colorectal and endometrial carcinomas in patients with Lynch-like syndrome versus patients with Lynch syndrome

Screening for DNA mismatch repair (MMR) deficiency in colorectal and endometrial carcinomas identifies patients at risk for Lynch syndrome. Some patients with MMR-deficient tumors have no evidence of a germline mutation and have been described as having Lynch-like syndrome. We compared the clinicopathological features of colorectal and endometrial carcinomas in patients with Lynch-like syndrome and Lynch syndrome. Universal screening identified 356 (10.6%) of 3352 patients with colorectal carcinoma and 72 (33%) of 215 patients with endometrial carcinoma with deficient DNA MMR. Sixty-six patients underwent germline mutation analysis with 45 patients (68%) having evidence of a germline MMR gene mutation confirming Lynch syndrome and 21 patients (32%) having Lynch-like syndrome with no evidence of a germline mutation. Most patients with Lynch-like syndrome had carcinoma involving the right colon compared to patients with Lynch syndrome (93% versus 45%; P < .002). All patients with colorectal carcinomas demonstrating isolated loss of MSH6 expression had Lynch syndrome confirmed by germline mutation analysis. Synchronous or metachronous Lynch syndrome-associated carcinoma was more frequently identified in patients with Lynch syndrome compared to Lynch-like syndrome (38% versus 7%; P = .04). There were no significant differences in clinicopathological variables between patients with Lynch-like syndrome and Lynch syndrome with endometrial carcinoma. In summary, 32% of patients with MMR deficiency concerning Lynch syndrome will have Lynch-like syndrome. Our results demonstrate that patients with Lynch-like syndrome are more likely to have right-sided colorectal carcinoma, less likely to have synchronous or metachronous Lynch syndrome-associated carcinoma, and less likely to demonstrate isolated loss of MSH6 expression within their tumor.

A comparison of right versus left-sided colorectal carcinoma for DNA mismatch repair and presence of putative CD133-stem cells

Right and left-sided colorectal carcinoma (CRC) are generally observed to differ in pathogenetic mechanisms, with deficiency of DNA mismatch repair (dMMR) leading to microsatellite instability occurring more commonly on the right. A study to assess the DNA mismatch repair status and presence of CD133-putative stem cells in 40 consecutive right and 40 left-sided formalin-fixed, paraffin-embedded CRC was carried out at the Department of Pathology, University of Malaya Medical Centre. Immunohistochemical staining for DNA mismatch repair gene products, MLH1, MSH2, MSH6 and PMS2 and CD133 were carried out on a Ventana XT autostainer. dMMR was significantly increased in right-sided (35%) compared with left-sided (0%) CRC. Of the dMMR cases, 10 had concomitant loss of MLH1 and PMS2, two concomitant loss of MSH2 and MSH6, one isolated loss of MSH6 and another of PMS2. CD133 immunoexpression score, arbitrarily computed as the semi-quantitative estimation of proportion of CRC immunopositive cells multiplied by intensity of staining was significantly lower (<i>p</i><0.05) in right (mean score=7.0) compared with left-sided tumours (mean score=9.9). The observations of a higher frequency of dMMR and lower CD133 expression in right-sided CRC further support the notion of dissimilar mechanisms involved in aetiology and evolution of right and left-sided tumours.

Clinical and pathological tools for identifying microsatellite instability in colorectal cancer

AimTo assess practical accuracy of revised Bethesda criteria (BGrev), pathological predictive model (MsPath), and histopathological parameters for detection of high-frequency of microsatellite instability (MSI-H) phenotype in patients with colorectal carcinoma (CRC).MethodTumors from 150 patients with CRC were analyzed for MSI using a fluorescence-based pentaplex polymerase chain reaction technique. For all patients, we evaluated age, sex, family history of cancer, localization, tumor differentiation, mucin production, lymphocytic infiltration (TIL), and Union for International Cancer Control stage. Patients were classified according to the BGrev, and the groups were compared. The utility of the BGrev, MsPath, and clinical and histopathological parameters for predicting microsatellite tumor status were assessed by univariate logistic regression analysis and by calculating the sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values.ResultsFifteen out of 45 patients who met and 4 of 105 patients who did not meet the BGrev criteria had MSI-H CRC. Sensitivity, specificity, PPV, and NPV for BGrev were 78.9%, 77%, 30%, and 70%, respectively. MSI histology (the third BGrev criterion without age limit) was as sensitive as BGrev, but more specific. MsPath model was more sensitive than BGrev (86%), with similar specificity. Any BGrev criterion fulfillment, mucinous differentiation, and right-sided CRC were singled out as independent factors to identify MSI-H colorectal cancer.ConclusionThe BGrev, MsPath model, and MSI histology are useful tools for selecting patients for MSI testing.

Abstract CN13-03: Next-generation stool DNA testing

Abstract CN13-03: Next-generation stool DNA testing

Longitudinal Outcome Study of Sessile Serrated Adenomas of the Colorectum: An Increased Risk for Subsequent Right-sided Colorectal Carcinoma

Sessile serrated adenomas (SSAs) are associated with colorectal carcinomas (CRCs) that demonstrate high microsatellite instability (MSI-H). Currently, SSAs are managed clinically in a similar fashion to adenomatous polyps (APs). We studied the natural history of SSA by analyzing the outcome of previously undiagnosed SSAs and comparing it with that of hyperplastic polyps (HPs) and APs. All colorectal polyps diagnosed between 1980 and 2001 as HP were selected for study. Polyps identified as possible SSAs were reviewed by 3 pathologists, and the diagnosis was confirmed. Clinical follow-up was obtained for each SSA patient and matched with control HP and AP patients. In total, 1402 colorectal polyps diagnosed as HP were examined and 81 polyps in 55 patients (5.8%) were rediagnosed as SSA. Of these, 40 SSA patients had no previous history of either CRC or AP with high-grade dysplasia (HGD). Of these 40 patients, 5 developed subsequent CRCs and 1 developed AP with HGD. The incidence of subsequent CRCs was significantly higher in SSA patients than in control patients with HP (12.5% vs. 1.8%) and AP (12.5% vs. 1.8%). All of the subsequent CRCs or APs with HGD developed in the proximal colon. Four of the 5 CRCs demonstrated a high microsatellite instability phenotype. We conclude that SSAs are high-risk lesions, with 15% of the SSA patients developing subsequent CRCs or APs with HGD. This incidence is higher than that of the control HP and AP patients, and would support close endoscopic follow-up in patients harboring SSAs.

Clinicopathologic Characteristics of Left-Sided Colon Cancers with High Microsatellite Instability

Background : High microsatellite instability (MSI-H) colorectal carcinomas (CRCs) with numerous mutations in the microsatellite sequence are characterized by a right-sided preponderance, frequent peritumoral and intratumoral lymphocytic infiltration, and frequent mucin production. However, no study has correlated anatomic site and type of genetic changes with clinicopathologic changes. Methods : We analyzed the histopathologic features of 135 MSI-H CRCs and compared them to 140 microsatellite stable (MSS) CRCs. Histopathologic changes in MSI-H were further analyzed according to anatomic sites and genetic changes. Results : MSI-H CRCs showed previously reported clinicopathologic findings; a right-sided preponderance, an increased number of mucinous carcinomas, and peritumoral lymphoid reactions (p<0.001 for each variable). Increased serum CEA levels showed an MSS CRC preponderance (p=0.013). We further analyzed the histologic differences between right- and left-sided MSI-H tumors. We found that MSI-H CRCs on both sides had similar clinicopathologic findings, except for higher tumor stage (p=0.048) and less frequent abnormal CEA levels in left-sided MSI-H tumors (p=0.027). We found that not all clinicopathologic features were different between hereditary nonpolyposis colorectal cancers (HNPCCs) and sporadic MSI-H CRCs. Conclusions : These findings indicate that MSI-H CRCs of the left colon have similar clinicopathologic characteristics as right-sided MSI-H CRCs. We did not find any significant clinicopathological difference between HNPCCs and sporadic MSI-H CRCs.

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.

A comparative study of the expression of Wnt-1, WISP-1, survivin and cyclin-D1 in colorectal carcinoma

It is well accepted that activation of Wnt signalling occurs in colorectal carcinoma (CRC), but the correlation amongst the various proteins involved in primary tumours are still unclear. The expression of the inducer of this pathway, Wnt-1, and the downstream effectors, WISP-1, cyclin-D1 and survivin proteins, was compared in a series of CRC tissues with the apparently normal adjacent tissues to determine the relationship of these proteins. Formalin-fixed, paraffin-embedded tissue samples of 47 CRCs surgically resected at the Kuala Lumpur Hospital (KLH) between 1999 and 2000 were used. Immunohistochemical staining with monoclonal antibodies against cyclin-D1 and survivin and polyclonal antibodies against Wnt-1 and WISP-1 was performed. Results of immunohistochemistry were analysed for correlation between biomolecules and histopathological data of the patients. Of the 47 CRCs, 26 (55.3%), 15 (31.9%), 5 (10.6%) and 28 (59.6%) of the tumours exhibited positivity for Wnt-1, WISP-1, cyclin D1 and survivin, respectively. A lower percentage of the 40 apparently normal adjacent tissues were found to be positive for Wnt-1 (7, 17.5%), WISP-1 (+/-5, 12.5%) and survivin (13, 32.5%), but cyclin D1 was not detected in any of them. Interestingly, the total scores of Wnt-1, WISP-1 and survivin were significantly higher in CRC tissues (p=0.001, 0.034 and 0.044, respectively). Using the Spearman rank correlation test, a positive linear relationship was found between total Wnt-1 score with total WISP-1 score (rho=0.319, p=0.003) and total survivin score (rho=0.609, p=or<0.001). The expression of WISP-1 in the CRC tissues was found to be positively correlated with patients older than 60 years old (p=0.011). In addition, nuclear cyclin-D1 expression was found to be associated with poorly differentiated CRC tissues (p<0.001, Table 5) and right-sided CRC tumour (p=0.019, Table 6). Total WISP-1 score was associated with well-differentiated CRC tissues (p=0.029). Overexpression and interplay between Wnt-1, WISP-1, survivin and cyclin-D1 may play a role in tumorigenesis, possibly by promoting cell cycle checkpoint progression, accelerating cell growth and inhibiting apoptosis. Our data may provide useful information towards the search for potent therapeutic targets towards the development of novel treatment strategies for CRC.

Colon Cancer???Associated DNA Mutations: Marker Selection for the Detection of Proximal Colon Cancer

This study evaluates the potential ability of a specific panel of DNA mutations to identify right-sided colorectal carcinomas (CRCs) that would be missed by a flexible sigmoidoscopy (FS) screening program. This panel could then be applied to stool DNA analysis for noninvasive proximal CRC detection. A series of resected right-sided CRCs from 101 patients who had no left-sided advanced colonic neoplasms distal to the splenic flexure were analyzed. Tumor DNA was isolated from microdissected tumor sections. Deletions in the BAT-26 locus, a marker of microsatellite instability, and mutations at 19 loci spread among the p53, K-ras, and Apc genes were detected following PCR amplification. Mutations were identified in 83% of successfully amplified samples and were variably present in each of the target sites: p53 (42%), Apc (37%), K-ras (28%), and BAT-26 (24%). Mutations were identified across all Dukes stages (CIS/A 6/8 [75%], B 41/51[80%], C 30/32 (94%), and D 6/9 [67%]). Our data suggest that this 20-marker mutation panel may be associated with more than 80% of cancers undetectable by FS. The adjunctive use of stool DNA mutation analysis using this marker panel in FS CRC screening programs may significantly increase the detection of proximal CRC.

Mutations of BRAF are associated with extensive hMLH1 promoter methylation in sporadic colorectal carcinomas.

Activating mutations of BRAF have been frequently observed in microsatellite unstable (MSI+) colorectal carcinomas (CRCs), in which mutations of BRAF and KRAS are mutually exclusive. Previously, we reported that hypermethylation of hMLH1 might play an important role in the tumorigenesis of right-sided sporadic CRCs with MSI showing less frequency of KRAS/TP53 alteration. Therefore, we have assumed that BRAF mutations might be highly associated with hMLH1 methylation status rather than MSI status. In this study, mutations of BRAF and KRAS and their relationship with MSI and hMLH1 methylation status were examined in 140 resected specimens of CRC. The methylation status was classified into 3 types: full methylation (FM), partial methylation (PM) and nonmethylation (NM). Only FM closely linked to reduced expression of hMLH1 protein. BRAF mutations were found in 16 cases (11%), all leading to the production of BRAF(V599E). As for MSI status, BRAF mutations were found in 43% of MSI+ and 4% of MSI- cases (p < 0.0001). Among the MSI+ individuals, BRAF mutations were more frequent in cases with hMLH1 deficiency (58%) than those with hMSH2 deficiency (0%; p=0.02). Moreover, they were found in 69% of FM, 4% of PM and 4% of NM, revealing a striking difference between FM and the other 2 groups (FM vs. PM or NM; p < 0.0001). These findings suggest that BRAF activation may participate in the carcinogenesis of sporadic CRCs with hMLH1 hypermethylation in the proximal colon, independently of KRAS activation.