Divergent oncogenic changes influence survival differences between colon and rectal adenocarcinomas

The psoas muscle density as a predictor of postoperative complications in elderly patients undergoing rectal cancer resection

Background

Muscle depletion that impairs normal physiological function in elderly patients leads to poor prognosis. This study aimed to evaluate the association between total abdominal muscle area (TAMA), total psoas area (TPA), psoas muscle density (PMD), and short-term postoperative complications in elderly patients with rectal cancer.

Methods

All elderly patients underwent rectal cancer resection with perioperative abdominal computed tomography (CT). Complications were assessed according to the Clavien-Dindo classification. Severe complications were defined as grade III-V following the Clavien-Dindo classification. Univariate and multivariate analyses were performed to evaluate risk factors of short-term severe postoperative complications.

Results

The cohort consisted of 191 patients with a mean age of 73.60 ± 8.81 years. Among them, 138 (72.25%) patients had Clavien-Dindo 0- II, 53 (27.75%) patients had severe postoperative complications (Clavien-Dindo III-V), and 1(0.52%) patient died within 30 days of surgery. PMD was significantly higher in the Clavien-Dindo 0-II cohort compared to the Clavien-Dindo III-V cohort (p=0.004). Nevertheless, TAMA and TPA failed to exhibit significant differences. Moreover, the multivariate regression analysis implied that advanced age [OR 1.07 95%CI (1.02-1.13) p=0.013], male [OR 5.03 95%CI (1.76-14.41) p=0.003], high charlson comorbidity index (CCI) score [OR 3.60 95%CI (1.44-9.00) p=0.006], and low PMD [OR 0.94 95%CI (0.88-0.99) p=0.04] were independent risk factors of Clavien-Dindo III-V.

Conclusion

Preoperative assessment of the PMD on CT can be a simple and practical method for identifying elderly patients with rectal cancer at risk for severe postoperative complications.

Identifying and ranking causal microbial biomarkers for colorectal cancer at different cancer subsites and stages: a Mendelian randomization study

Introduction

The gut microbiome is directly involved in colorectal carcinogenesis, but much of the epidemiological evidence for the effect of the gut microbiome on colorectal cancer (CRC) risk comes from observational studies, and it is unclear whether identified microbial alterations are the cause or consequence of CRC development.

Methods

Univariate Mendelian randomization (MR) analysis and multivariate MR analysis based on Bayesian model averaging were performed to comprehensively explore the microbial risk factors associated with CRC. The Network Module Structure Shift method was used to identify microbial biomarkers associated with CRC. Mediation analysis was used to explore the dietary habits-microbiota-CRC pathway.

Results

The results of the four methods showed that 9 bacteria had a robust causal relationship with the development of CRC. Among them, Streptococcus thermophilus reduced the risk of CRC; Eubacterium ventriosum and Streptococcus were beneficial bacteria of malignant tumors of colon (CC); Erysipelotrichaceae was a protective factor for malignant tumors of rectal (CR); Bacteroides ovatus was a risk factor for benign tumors. Finally, the mediation analysis revealed 10 pathways by which dietary regulation bacteria affected the risk of CRC, including alcohol consumption increased the risk of CC by reducing the abundance of Eubacterium ventriosum (mediated proportion: 43.044%), and the mediated proportion of other pathways was 7.026%-34.22%.

Discussion

These findings will contribute to the understanding of the different carcinogenic mechanisms of intestinal flora in the colon and rectum and the risk of tumor transformation, thereby aiding CRC prevention, early screening, and the development of future strategies to reduce CRC risk.

A predictive role of C-reactive protein in colorectal cancer risk: an updated meta-analysis from 780,985 participants and 11,289 cancer cases

PURPOSE

This meta-analysis is aimed at understanding the potential role of circulating C-reactive protein (CRP) in the prediction of colorectal cancer (CRC) risk and the potential effect of relevant variables, with specific concern to determine the incorporation of CRP into a CRC risk prediction model.

METHODS

Relevant articles on the association between circulating CRP and CRC risk were searched from PubMed, Embase, Web of Science, and Cochrane Database of Systematic Reviews through August 2022. Random-effects models were used to estimate the pooled relative risk (RR) for the highest versus lowest CRP categories. Linear and non-linear trend analyses were conducted to explore the dose-response associations between CRP and CRC risk.

RESULTS

Twenty-three articles including 780,985 participants and 11,289 cancer cases met the selection criteria. The overall result demonstrated a remarkable association between elevated CRP levels and CRC risk (RR, 1.259; 95% CI, 1.060-1.457), but not in dose-response analysis (RR, 1.002 (95% CI, 0.964-1.041) per natural log unit change in CRP). Subgroup analyses indicated a significant difference when grouped by study location, the length of follow-up, and gender composition. No evidence of publication bias was observed.

CONCLUSION

The predictive role of CRP in CRC incidence is limited to colon cancer and a period of 10 years after the initial discovery of CRP elevation. The result did not support the etiological role of CRP in CRC and the inclusion of CRP into the CRC risk prediction model.

Meta-Analysis of the Prognostic and Predictive Role of the CpG Island Methylator Phenotype in Colorectal Cancer

Background

Various studies have produced contradictory results on the prognostic role of the CpG island methylator phenotype (CIMP) among colorectal cancer (CRC) patients. Although a meta-analysis published in 2014 reported a worse prognosis of CIMP among CIMP-high (CIMP-H) CRC patients, the sample sizes of the major included studies were small. In this study, we included the most recent studies with large sample sizes and performed an updated meta-analysis on the relationship between CIMP and CRC prognosis.

Methods

A search of MEDLINE, Web of Science, and Cochrane for studies related to CIMP and CRC published until July 2021 was conducted based on the PICO (participant, intervention, control, outcome) framework. Data extraction and literature analyses were performed according to PRISMA standards.

Results

In the present update, 36 eligible studies (20 recently published) reported survival data in 15315 CRC patients, 18.3% of whom were characterized as CIMP-H. Pooled analysis suggested that CIMP-H was associated with poorer overall survival (OS) (hazard ratio [HR] = 1.37, 95% CI: 1.26–1.48) and disease-free survival/progression-free survival/recurrence-free survival (DFS/PFS/RFS) (HR = 1.51, 95% CI: 1.19–1.91) among CRC patients. Subgroup analysis based on tumor stage and DNA mismatch repair (MMR) status showed that only patients with stages III-IV and proficient MMR (pMMR) tumors showed a significant association between CIMP-H and shorter OS, with HRs of 1.52 and 1.37, respectively. Three studies were pooled to explore the predictive value of CIMP on CRC patient DFS after receiving postoperative chemotherapy, and no significant correlation was found.

Conclusion

CIMP-H is associated with a significantly poor prognosis in CRC patients, especially those with stage III-IV and pMMR tumors. However, the predictive value of CIMP needs to be confirmed by more prospective randomized studies.

Right colon, left colon, and rectal cancer have different oncologic and quality of life outcomes

PURPOSE

Colorectal cancer patients are commonly considered a single entity in outcomes studies. This is particularly true for quality of life (QOL) studies. This study aims to compare oncologic and QOL outcomes between right colon, left colon, and rectal cancer in patients operated on in a single high-volume institution.

METHODS

A prospectively maintained database was queried to identify patients with pathological stages I-III colorectal adenocarcinoma electively operated on with curative intent between 2000 and 2010. Patient characteristics, perioperative and oncologic outcomes, and QOL were compared according to cancer location.

RESULTS

Two-thousand sixty-five (606 right colon cancer [RCC], 366 left colon cancer [LCC], and 1093 rectal cancer [RC]) patients met the inclusion criteria. LCC had better overall survival (OS) and disease-free survival (DFS) in the non-adjusted analysis (p < 0.001) and better OS in multivariate analysis adjusted by age, gender, ASA, chemotherapy, and pathological stage (p = 0.024). Although RCC had worse OS and DFS in non-adjusted survival analysis than LCC and RC, when adjusted for the factors above, RCC had better survival outcomes than RC, but not LCC. COX regression analysis showed age (p < 0.001), gender (p = 0.016), ASA (p < 0.001), pathological stage (p < 0.001), adjuvant chemotherapy (p = 0.043), and cancer location (p = 0.024) were independently associated with OS. Age (p < 0.001), gender (p = 0.030), ASA (p = 0.004), and pathological stage (p < 0.001) were independently associated with DFS. Patients with RC reported more sexual dysfunction and work restrictions than colon cancers (p = 0.015 and p < 0.001, respectively).

CONCLUSION

In an adjusted multivariate analysis, colon cancers demonstrated better survival outcomes when compared to rectal cancers.

Mutant KRAS as a prognostic biomarker after hepatectomy for rectal cancer metastases: Does the primary disease site matter?

BACKGROUND

The prognostic implication of mutant KRAS (mKRAS) among patients with primary disease in the rectum remains unknown.

METHODS

From 2000 to 2018, patients undergoing hepatectomy for colorectal liver metastases at 10 collaborating international institutions with documented KRAS status were surveyed.

RESULTS

A total of 834 (65.8%) patients with primary colon cancer and 434 (34.2%) patients with primary rectal cancer were included. In patients with primary colon cancer, mKRAS served as a reliable prognostic biomarker of poor overall survival (OS) (hazard ratio [HR]: 1.58, 95% CI 1.28-1.95) in the multivariable analysis. Although a trend towards significance was noted, mKRAS was not found to be an independent predictor of OS in patients with primary rectal tumors (HR 1.34, 95% CI 0.98-1.80). For colon cancer, the specific codon impacted in mKRAS appears to reflect underlying disease biology and oncologic outcomes, with codon 13 being associated with particularly poor OS in patients with left-sided tumors (codon 12, HR 1.56, 95% CI 1.22-1.99; codon 13, HR 2.10 95% CI 1.43-3.08;). Stratifying the rectal patient population by codon mutation did not confer prognostic significance following hepatectomy.

CONCLUSIONS

While the left-sided colonic disease is frequently grouped with rectal disease, our analysis suggests that there exist fundamental biologic differences that drive disparate outcomes. Although there was a trend toward significance of KRAS mutations for patients with primary rectal cancers, it failed to achieve statistical significance.

A Prognostic Nomogram of Colon Cancer With Liver Metastasis: A Study of the US SEER Database and a Chinese Cohort

Background

Among colon cancer patients, liver metastasis is a commonly deadly phenomenon, but there are few prognostic models for these patients.

Methods

The clinicopathologic data of colon cancer with liver metastasis (CCLM) patients were downloaded from the Surveillance, Epidemiology and End Results (SEER) database. All patients were randomly divided into training and internal validation sets based on the ratio of 7:3. A prognostic nomogram was established with Cox analysis in the training set, which was validated by two independent validation sets.

Results

A total of 5,700 CCLM patients were included. Age, race, tumor size, tumor site, histological type, grade, AJCC N status, carcinoembryonic antigen (CEA), lung metastasis, bone metastasis, surgery, and chemotherapy were independently associated with the overall survival (OS) of CCLM in the training set, which were used to establish a nomogram. The AUCs of 1-, 2- and 3-year were higher than or equal to 0.700 in the training, internal validation, and external validation sets, indicating the favorable effects of our nomogram. Besides, whether in overall or subgroup analysis, the risk score calculated by this nomogram can divide CCLM patients into high-, middle- and low-risk groups, which suggested that the nomogram can significantly determine patients with different prognosis and is suitable for different patients.

Conclusion

Higher age, the race of black, larger tumor size, higher grade, histological type of mucinous adenocarcinoma and signet ring cell carcinoma, higher N stage, RCC, lung metastasis, bone metastasis, without surgery, without chemotherapy, and elevated CEA were independently associated with poor prognosis of CCLM patients. A nomogram incorporating the above variables could accurately predict the prognosis of CCLM.

Surgical management of recurrent colon cancer

There have been significant developments in the management of advanced and recurrent colorectal cancer in recent decades. 70% of primary colorectal tumours arise in the colon and for patients with stage I-III disease, the standard of care is surgical resection followed by adjuvant therapy where appropriate. Locoregional recurrence (LR) occurs in 4-11.5% of patients following treatment of primary colon cancer with curative intent, and can be categorised as peri-anastomotic, mesenteric/paracolic (nodal), retroperitoneal and peritoneal. Of these, peritoneal recurrence is usually recognised as the most challenging type of recurrence to manage. Patients with isolated peri-anastomotic or limited nodal recurrence in the mesentery or retroperitoneum may be curable by radical salvage surgery, which often requires en bloc multi-visceral resection, while patients with low volume peritoneal metastases may be candidates for cytoreductive surgery with hyperthermic intraperitoneal chemotherapy. Ensuring complete resection along embryonic mesocolic planes or en bloc resection of contiguously involved structures are best strategies to reduce the likelihood of local recurrence through a R1 resection margin. The role of complete mesocolic excision (CME) with high vascular ligation has been demonstrated to increase nodal yield and improve overall survival although this is more contentious. In patients with T4a disease and serosal surface involvement, peritoneal recurrence represents the greatest threat. Efforts for early diagnosis of peritoneal recurrence in these patients or prophylactic treatment, while intuitive have not demonstrated the survival benefit that would be expected. Other than locoregional recurrence (LR), systemic recurrence may occur in up to 50% of patients who have undergone curative resection for colorectal cancer. In keeping with portal venous outflow, the most common site of systemic recurrence is the liver. Although previously thought to be a fatal condition, liver resection is now the standard of care where liver metastases can be completely resected with clear margins plus leaving an adequate liver remnant with intact vascular inflow, outflow and biliary drainage. This can usually be achieved in 26-45% of patients presenting with liver metastases. Liver surgeons at the forefront of liver resection have also developed techniques to induce liver hypertrophy so as to improve likelihood of resectability. Even where patients have non-resectable disease, ablative techniques have become increasingly common. Naturally, none of these would be possible without the advent of improved chemotherapeutic and biological options in the field of medical oncology. Pulmonary metastasectomy with curative intent may be possible in a small number (10%) of patients with lung metastases, which is associated with an overall survival of up to 40%. Unlike liver metastases, proportionally less patients with pulmonary metastases will be resectable. For these patients, several ablative options are available. For all patients with recurrent colon cancer, patient selection for radical salvage surgery and decisions surrounding treatment strategy (including use of systemic therapy or ablative procedures) should take place in a multidisciplinary team setting.

Tumor sidedness influences prognostic impact of lymph node metastasis in colon cancer patients undergoing curative surgery

This study aimed to evaluate prognostic impacts of the number of lymph nodes (LNs) examined and LN ratio on cancer-specific mortality after surgery in patients with right-sided colon cancer (RCC) or left-sided colon cancer (LCC) using the Surveillance, Epidemiology, and End Results database. Number of LNs examined and LN ratio were treated as categorical and/or continuous. Competing risks proportional hazards regressions adjusted by propensity score were performed. All included patients had stage I, II, or III disease, and 45.1% of them had RCC. RCC and LCC patients with high level of LNs examined had better prognosis after segmental resection or hemicolectomy. RCC and LCC patients with higher LN ratio had worse prognosis regardless of surgery. Survival benefit of having high level of LNs examined was observed in RCC patients with stage I, II, or III disease, but only in LCC patients with stage II disease. Both higher LN ratio and high level of LN were negative prognostic factors for cancer-specific mortality in stage III patients regardless of tumor sidedness. In conclusion, RCC patients in various conditions had worse or comparable prognosis compared to their LCC counterparts, which reflected the severity of LN metastasis.

High KCNQ1OT1 expression might independently predict shorter survival of colon adenocarcinoma

AIM

To explore the expression profile of KCNQ1OT1 and its prognostic value in colon and rectal adenocarcinoma (COAD and READ) separately.

PATIENTS & METHODS

clinicopathological, genomic and survival data from The Cancer Genome Atlas and GSE39582 were obtained for a secondary analysis.

RESULTS

KCNQ1OT1 was significantly up-regulated in both COAD and READ compared with adjacent normal tissues. However, its up-regulation was only independently associated with shorter overall survival (hazard ratio: 2.02; 95% CI: 1.18-3.46; p = 0.01) and recurrence-free survival (hazard ratio: 2.79, 95% CI: 1.54-5.07; p < 0.01) in COAD, but not in READ.

CONCLUSION

KCNQ1OT1 up-regulation might serve as a valuable independent prognostic indicator of shorter overall survival and recurrence-free survival of COAD, but not READ.

Postoperative Outcomes of Screen-Detected vs Non-Screen-Detected Colorectal Cancer in the Netherlands

Importance

The nationwide fecal immunochemical test-based screening program has influenced surgical care for patients with colorectal cancer (CRC) in the Netherlands, although these implications have not been studied in much detail so far.

Objective

To compare surgical outcomes of patients diagnosed as having CRC through the fecal immunochemical test-based screening program (screen detected) and patients with non-screen-detected CRC.

Design, Setting, and Participants

This was a population-based comparative cohort study using the Dutch ColoRectal Audit and analyzed all Dutch hospitals performing CRC resections. Patients who underwent elective resection for CRC between January 2011 to December 2016 were included.

Interventions

Colorectal cancer surgery.

Main Outcomes and Measures

Postoperative nonsurgical complications, postoperative surgical complications, postoperative 30-day or in-hospital mortality, and complicated course (postoperative complication resulting in a hospital stay >14 days and/or a reintervention and/or mortality). A risk-stratified comparison was made for different postoperative outcomes based on screening status (screen detected vs not screen detected), cancer stage (I-IV), and for cancer stage I to III also on age (aged ≤70 years and >70 years) and American Society of Anesthesiologists score (I-II and III-IV). To determine any residual case-mix-corrected differences in outcomes between patients with screen-detected and non-screen-detected cancer, univariable and multivariable logistic regression analyses were performed.

Results

In total, 36 242 patients with colon cancer and 17 416 patients with rectal cancer were included for analysis. Compared with patients with non-screen-detected CRC, screen-detected patients were younger (mean [SD] age, 68 [5] vs 70 [11] years), more often men (3777 [60%] vs 13 506 [57%]), and had lower American Society of Anesthesiologists score (American Society of Anesthesiologists score III+: 838 [13%] vs 5529 [23%]). Patients with stage I to III colon cancer who were screen detected had a significantly lower mortality and complicated course rate compared with non-screen-detected patients. For patients with rectal cancer, only a significant difference was found in mortality rate in patients with a cancer stage IV disease, which was higher in the screen-detected group. Compared with non-screen-detected colon cancer, an independent association was found for screen-detected colon cancer on nonsurgical complications (adjusted odds ratio, 0.81; 95% CI, 0.73-0.91), surgical complications (adjusted odds ratio, 0.80; 95% CI, 0.72-0.89), and complicated course (adjusted odds ratio, 0.80; 95% CI, 0.71-0.90). Screen-detected rectal cancer had significantly higher odds on mortality.

Conclusions and Relevance

Postoperative outcomes were significantly better for patients with colon cancer referred through the fecal immunochemical test-based screening program compared with non-screen-detected patients. These differences were not found in patients with rectal cancer. The outcomes of patients with screen-detected colon cancer were still better after an extensive case-mix correction, implying additional underlying factors favoring patients referred for surgery through the screening program.

Epigenetically regulated miR-1247 functions as a novel tumour suppressor via MYCBP2 in methylator colon cancers

Background

Colorectal cancer (CRC) is a heterogeneous disease with distinct clinical subsets based on underlying genetic and epigenetic changes. DNA hypermethylation yields a unique CRC subset with a distinct phenotype and clinical behaviour, but this oncogenic pathway is not fully characterised. This study identifies and characterises miR-1247 as a novel tumour suppressor microRNA in methylated human colon cancers.

Method

Tumour samples from patients with hypermethylated and non-methylated colon cancer and cell lines were evaluated for miR-1247 expression and function. A murine subcutaneous xenograft model was used for in vivo functional studies.

Results

miR-1247 was methylated and underexpressed in methylator colon cancers. Overexpression of miR-1247 significantly inhibited cell proliferation, decreased tumour cell motility, induced apoptosis, and mitigated tumour formation capacity both in vivo and in vitro. Pharmacologic demethylation increased miR-1247 expression and produced similar anti-tumour activities. Mechanistic investigations revealed that MYCBP2, a member of the c-myc oncogene family, is a direct functional target of miR-1247. Furthermore, in CRC patients, MYCBP2 protein levels are associated with miR-1247 levels and survival.

Conclusions

miR-1247 acts as a tumour suppressor by inhibiting MYCBP2 in methylator colon cancer. The MYCBP2/c-myc axis may underlie the anti-tumour activities of miR-1247 and is a potential therapeutic target via demethylation agents.

Proteome Heterogeneity in Colorectal Cancer

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

Molecular Biology: Are We Getting Any Closer to Providing Clinically Useful Information?

Advances in molecular biology and biomarker research have significantly impacted our understanding and treatment of multiple solid malignancies. In rectal cancer, where neoadjuvant chemoradiation is widely used for locally advanced disease, most efforts have focused on the identification of predictors of response in an attempt to appropriately select patients for multimodality therapy. A variety of biomarkers have been studied, including genetic mutations, chromosomal copy number alterations, and single as well as multigene expression patterns. Also, as transanal resection of rectal tumors requires accurate preoperative detection of lymph node metastasis, the identification of biomarkers of regional nodal involvement has been another important field of active research. While preliminary results have been promising, lack of external validation means has a limited translation to clinical use. This review summarizes recent developments in rectal cancer biomarker research, highlighting the challenges associated with their adoption, and evaluating their potential for clinical use.

The impacts of surgery of the primary cancer and radiotherapy on the survival of patients with metastatic rectal cancer

The role of surgery of the primary cancer and radiation in metastatic colorectal cancer (mCRC) is still controversial currently, and evidence implied that colon cancer (CC) and rectal cancer (RC) should be treated with difference. Hence we focused on metastatic rectal cancer (mRC) solely to compare the cancer cause-specific survival (CSS) of patients receiving varied treatments of the primary cancer: no treatment, surgery only, radiation only, and surgery plus radiation, based on the records of the Surveillance, Epidemiology, and End Results (SEER) database. A total of 8669 patients were included. Results demonstrated that the 2-year CSS was 28.1% for no treatment group, 30.7% for only radiation group, 50.2% for only surgery group, and 66.5% for surgery plus radiation group, reaching statistical difference (P < 0.001). Furthermore, the CSSs of mRC patients in the surgery group were similar regardless of resection ranges (P = 0.44). Besides, we analyzed the prognostic factors for mRC and found carcinoembryonic antigen (CEA) level, metastasis (M) stage, Tumor (T) stage, tumor size, differentiate grade, age and marital status should be taken into consideration when estimating the prognosis. Particularly, patients with normal CEA level or M1a stage showed a significant survival advantage. Overall, present study suggested that surgery of the primary cancer and radiation might help to improve the survival of mRC patients, especially when both treatments were conducted. Our results may assist clinicians to make better treatment strategy for patients with mRC.

BRAF mutation is associated with poor clinicopathological outcomes in colorectal cancer: A meta-analysis

BACKGROUND/AIMS

The clinical relevance of the BRAF mutation in colorectal carcinoma (CRC) remains controversial. We performed a comprehensive meta-analysis to evaluate the precise relationship of BRAF mutation to clinicopathological features.

MATERIALS AND METHODS

A systematic search of the electronic databases, including PubMed, the Web of Knowledge, and the China Journal Net was performed between January 2005 and December 2015. Outcomes of interest included gender, tumor site, tumor differentiation, node involvement, tumor size, and AJCC stage. We calculated the pooled odds ratios (ORs) or risk ratios with 95% confidence intervals (CIs) for each study using a random or fixed-effect model.

RESULTS

Twenty-five studies with a total of 13208 patients were included. BRAF mutation-positive CRC patients were 1464 (11.1%). Our meta-analysis revealed that, in patients with CRC, the BRAF mutation was associated with female, proximal site, poor differentiation, >5 cm size, and advanced AJCC stage.

CONCLUSIONS

This meta-analysis demonstrated that BRAF mutation was closely related to adverse pathological features and poor outcome of CRC.

Tumor LINE-1 Methylation Level in Association with Survival of Patients with Stage II Colon Cancer

Genome-wide DNA hypomethylation is associated with a worse prognosis in early-stage colorectal cancer. To measure genome-wide DNA methylation levels, long interspersed nucleotide element (LINE-1) repeats are used as a surrogate marker. Cohort studies on the clinical impact of genome-wide DNA methylation level in patients with only early-stage colon cancer, are currently lacking. This study aimed to investigate the prognostic value of LINE-1 methylation in a stage II colon cancer cohort (n = 164). Manual needle microdissection of tumor areas was performed on formalin-fixed paraffin-embedded tumor tissue sections followed by DNA extraction. Bisulfite converted DNA was used to assess tumor LINE-1 methylation level by qPCR. Patients with LINE-1 hypomethylated tumors had a significantly worse overall survival compared to patients with a higher level of LINE-1 tumor DNA methylation (HR 1.68, 95% CI 1.03–2.75; p = 0.04). This effect was more prominent in patients aged over 65 years (HR 2.00, 95% CI 1.13–3.52; p = 0.02), although the test for age interaction was not significant. No significant effect on recurrence-free survival was observed. Based on these results, tumor LINE-1 hypomethylation is associated with a worse overall survival in stage II colon cancer. Whether the origin of this causation is cancer-specific or age-related can be debated.

A stromal cell population in the large intestine identified by tissue factor expression that is lost during colorectal cancer progression

Colorectal cancer (CRC) is a major cause of morbidity and mortality, and the composition of the tumour stroma is a strong predictor of survival in this cancer type. Tissue factor (TF) functions as the trigger of haemostasis together with its ligand coagulation factor VII/VIIa, and TF expression has been found in tumour cells of colorectal tumours. However, TF expression in the CRC tumour stroma or its relationship to patient outcome has not yet been studied. To address this question we developed and validated a specific anti-TF antibody using standardised methods within the Human Protein Atlas project. We used this antibody to investigate TF expression in normal colorectal tissue and CRC using immunofluorescence and immunohistochemistry in two patient cohorts. TF was strongly expressed in a cell population immediately adjacent to the colorectal epithelium. These TF-positive cells were ACTA2-negative but weakly vimentin-positive, defining a specific population of pericryptal sheath cells. In colorectal tumours, TF-positive sheath cells were progressively lost after the adenoma-to-carcinoma transition, demonstrating downregulation of this source of TF in CRC. Furthermore, loss of sheath cell TF was significantly associated with poor overall and disease-specific survival in rectal but not colon cancers. In conclusion, we demonstrate that TF is a marker of a specific cell population in the large intestine, which is lost during CRC progression. Our results highlight the role of the tumour stroma in this cancer type and suggest TF to be a potential prognostic biomarker in rectal cancers through the identification of pericryptal sheath cells.

The "Studded" Rectum: Phenotypic Evidence of MYH-Associated Polyposis

BACKGROUND

MYH-associated polyposis is a recessively inherited syndrome of colorectal cancer predisposition attributed to biallelic germline mutations in the base excision repair gene MYH. Clinically it overlaps with attenuated familial adenomatous polyposis, sporadic oligopolyposis, serrated polyposis, familial colorectal cancer type X, and Lynch syndrome. There is no specific phenotypic feature of MYH-associated polyposis. We have noticed that a proportion of patients with MYH-associated polyposis presenting for yearly colonoscopy surveillance have rectums that are studded with small hyperplastic polyps.

OBJECTIVE

We report this as a possible unique phenotypic feature of the syndrome.

DESIGN

This was a descriptive study.

SETTINGS

The study was conducted at a department of colorectal surgery in a tertiary referral center.

PATIENTS

Patients affected with oligopolyposis or MYH-associated polyposis presenting for endoscopic surveillance and polyp control were included.

INTERVENTIONS

Interventions included colonoscopy or proctoscopy with excision or biopsy of mucosal lesions.

MAIN OUTCOME MEASURES

The presence of rectal studding was measured.

RESULTS

There were 49 patients, 16 with biallelic germline mutations of MYH; 10 of these had rectal studding. A sampling of rectal polyps was biopsied and all were hyperplastic. Five patients with biallelic MYH mutations had no studding, and 1 had not been prospectively examined. The studding was independent of the nature of the MYH mutation(s). The 33 patients other patients included 21 with serrated polyposis, 2 with a germline APC mutation, 1 with a PTEN mutation, 2 with mixed polyposis, 3 with oligoadenomatous polyposis and no germline mutation, and 4 patients with oligoadenomatous polyposis who had not been genetically tested. Only 1 of these (oligoadenomatous polyposis, not tested) had studding.

LIMITATIONS

The study was limited by its small number of biallelic MYH mutation carriers.

CONCLUSIONS

Rectal studding may be a sign of MYH-associated polyposis and raises questions about the biology of abnormal base excision repair.

MicroRNA in rectal cancer

In rectal cancer, one of the most common cancers worldwide, the proper staging of the disease determines the subsequent therapy. For those with locally advanced rectal cancer, a neoadjuvant chemoradiotherapy (CRT) is recommended before any surgery. However, response to CRT ranges from complete response (responders) to complete resistance (non-responders). To date we are not able to separate in advance the first group from the second, due to the absence of a valid biomarker. Therefore all patients receive the same therapy regardless of whether they reap benefits. On the other hand almost all patients receive a surgical resection after the CRT, although a watch-and-wait procedure or an endoscopic resection might be sufficient for those who responded well to the CRT. Being highly conserved regulators of gene expression, microRNAs (miRNAs) seem to be promising candidates for biomarkers. Many studies have been analyzing the miRNAs expressed in rectal cancer tissue to determine a specific miRNA profile for the ailment. Unfortunately, there is only a small overlap of identified miRNAs between different studies, posing the question as to whether different methods or differences in tissue storage may contribute to that fact or if the results simply are not reproducible, due to unknown factors with undetected influences on miRNA expression. Other studies sought to find miRNAs which correlate to clinical parameters (tumor grade, nodal stage, metastasis, survival) and therapy response. Although several miRNAs seem to have an impact on the response to CRT or might predict nodal stage, there is still only little overlap between different studies. We here aimed to summarize the current literature on rectal cancer and miRNA expression with respect to the different relevant clinical parameters.

Different definitions of CpG island methylator phenotype and outcomes of colorectal cancer: a systematic review

Contradictory results were reported for the prognostic role of CpG island methylator phenotype (CIMP) among colorectal cancer (CRC) patients. Differences in the definitions of CIMP were the most common explanation for these discrepancies. The aim of this systematic review was to give an overview of the published studies on CRC prognosis according to the different definitions of CIMP. A systematic literature search was performed in MEDLINE and ISI Web of Science for articles published until 3 April 2015. Data extraction included information about the study population, the definition of CIMP, and investigated outcomes. Thirty-six studies were included in this systematic review. Among them, 30 studies reported the association of CIMP and CRC prognosis and 11 studies reported the association of CIMP with survival after CRC therapy. Overall, 16 different definitions of CIMP were identified. The majority of studies reported a poorer prognosis for patients with CIMP-positive (CIMP+)/CIMP-high (CIMP-H) CRC than with CIMP-negative (CIMP-)/CIMP-low (CIMP-L) CRC. Inconsistent results or varying effect strengths could not be explained by different CIMP definitions used. No consistent variation in response to specific therapies according to CIMP status was found. Comparative analyses of different CIMP panels in the same large study populations are needed to further clarify the role of CIMP definitions and to find out how methylation information can best be used to predict CRC prognosis and response to specific CRC therapies.

Elevated CA19-9 as the Most Significant Prognostic Factor in Locally Advanced Rectal Cancer Following Neoadjuvant Chemoradiotherapy

It remains controversial regarding the prognostic significance of carbohydrate antigen 19-9 (CA19-9) for locally advanced rectal cancer (LARC) (T3-4/N+) patients with neoadjuvant chemoradiotherapy (neo-CRT). And it is unknown whether CA19-9 can identify patients who may benefit from adjuvant chemotherapy.Overall, 303 LARC patients with neo-CRT between 2004 and 2010 were recruited. Overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and local recurrence-free survival across pretreatment CA19-9 were estimated by Kaplan-Meier method and Cox regression model.In univariate analysis, elevated CA19-9 (>35 U/mL) was significantly correlated with poor OS (P = 0.003), DFS (P = 0.001), and DMFS (P = 0.039). Adjusting for the known covariates, CA19-9 was significantly associated with OS (HR = 1.86, 95% CI 1.03-3.34, P = 0.039) and DFS (HR = 1.74, 95% CI 1.08-2.80, P = 0.024). In the elevated CA19-9 subgroup, patients with adjuvant chemotherapy got much better OS (P < 0.001) and DFS (P = 0.016) than those without. In consideration of both CA19-9 and carcinoembryonic antigen (CEA), we found that patients with both elevated CA19-9 and CEA (>5 ng/mL) got the worst OS (P = 0.021) and DFS (P = 0.006), and significantly benefited from adjuvant chemotherapy in OS (P < 0.001) and DFS (P = 0.026).Pretreatment CA19-9 level is a significant prognostic indicator in patients with LARC following neo-CRT. The addition of CA19-9 to CEA is valuable to discriminate the appropriate patients for adjuvant chemotherapy.

Higher freshwater fish and sea fish intake is inversely associated with colorectal cancer risk among Chinese population: a case-control study

The association between specific fish intake and colorectal cancer risk remains controversial. This study aimed to examine the association between specific fish intake and colorectal cancer risk in Chinese population in a large case control study. During July 2010 to November 2014, 1189 eligible colorectal cancer cases and 1189 frequency-matched controls (age and sex) completed in-person interviews. A validated food frequency questionnaire was used to estimate dietary intake. Multivariate logistical regression models were used to estimate the odds ratio (OR) and 95% confidence interval (95% CI) after adjusting for various confounders. A strong inverse association was found between freshwater fish intake and colorectal cancer risk. Compared with the lowest quartile, the highest quartile intake showed a risk reduction of 53% (OR 0.47, 95% CI = 0.36-0.60, Ptrend < 0.01) after adjustment for various confounders. The inverse association were also observed for sea fish (OR 0.79, 95%CI = 0.62-0.99, Ptrend < 0.01) and fresh fish (OR 0.49, 95%CI = 0.38-0.62, Ptrend < 0.01). No statistically significant association was found between dried/salted fish and shellfish intake and colorectal cancer risk. These results indicate that higher consumption of freshwater fish, sea fish and fresh fish is associated with a lower risk of colorectal caner.

A perspective on the current treatment strategies for locally advanced rectal cancer

The introduction of total mesorectal excision (TME) and preoperative multimodality treatment have substantially improved the management of rectal cancer reducing local recurrence and increasing sphincter-saving surgery; distant metastases however remain a clinical challenge. Besides, although surgery remains the mainstay for cure of rectal cancer with the multimodality approach (chemotherapy, radiotherapy and surgery) being the standard of care for the majority of rectal cancer patients, there is a need of individualized risk-adapted treatment schemes based on clinico-pathological features because of treatment-induced morbidity and quality of life deterioration. This short viewpoint describes the emerging strategies addressing all these issues.

Adjuvant chemotherapy after preoperative (chemo)radiotherapy and surgery for patients with rectal cancer: a systematic review and meta-analysis of individual patient data

BACKGROUND

The role of adjuvant chemotherapy for patients with rectal cancer after preoperative (chemo)radiotherapy and surgery is uncertain. We did a meta-analysis of individual patient data to compare adjuvant chemotherapy with observation for patients with rectal cancer.

METHODS

We searched PubMed, Medline, Embase, Web of Science, the Cochrane Library, CENTRAL, and conference abstracts to identify European randomised, controlled, phase 3 trials comparing observation with adjuvant chemotherapy after preoperative (chemo)radiotherapy and surgery for patients with non-metastatic rectal cancer. The primary endpoint of interest was overall survival.

FINDINGS

We analysed data from four eligible trials, including data from 1196 patients with (y)pTNM stage II or III disease, who had an R0 resection, had a low anterior resection or an abdominoperineal resection, and had a tumour located within 15 cm of the anal verge. We found no significant differences in overall survival between patients who received adjuvant chemotherapy and those who underwent observation (hazard ratio [HR] 0.97, 95% CI 0.81-1.17; p=0.775); there were no significant differences in overall survival in subgroup analyses. Overall, adjuvant chemotherapy did not significantly improve disease-free survival (HR 0.91, 95% CI 0.77-1.07; p=0.230) or distant recurrences (0.94, 0.78-1.14; p=0.523) compared with observation. However, in subgroup analyses, patients with a tumour 10-15 cm from the anal verge had improved disease-free survival (0.59, 0.40-0.85; p=0.005, p(interaction)=0.107) and fewer distant recurrences (0.61, 0.40-0.94; p=0.025, p(interaction)=0.126) when treated with adjuvant chemotherapy compared with patients undergoing observation.

INTERPRETATION

Overall, adjuvant fluorouracil-based chemotherapy did not improve overall survival, disease-free survival, or distant recurrences. However, adjuvant chemotherapy might benefit patients with a tumour 10-15 cm from the anal verge in terms of disease-free survival and distant recurrence. Further studies of preoperative and postoperative treatment for this subgroup of patients are warranted.

FUNDING

None.

Portrait of the PI3K/AKT pathway in colorectal cancer

PI3K/AKT signaling leads to reduced apoptosis, stimulates cell growth and increases proliferation. Under normal conditions, PI3K/AKT activation is tightly controlled and dependent on both extracellular growth signals and the availability of amino acids and glucose. Genetic aberrations leading to PI3K/AKT hyper-activation are observed at considerable frequency in all major nodes in most tumors. In colorectal cancer the most commonly observed pathway changes are IGF2 overexpression, PIK3CA mutations and PTEN mutations and deletions. Combined, these alterations are found in about 40% of large bowel tumors. In addition, but not mutually exclusive to these, KRAS mutations are observed at a similar frequency. There are however additional, less frequent and more poorly understood events that may also push the PI3K/AKT pathway into overdrive and thus promote malignant growth. Here we discuss aberrations of components at the genetic, epigenetic, transcriptional, post-transcriptional, translational and post-translational level where perturbations may drive excessive PI3K/AKT signaling. Integrating multiple molecular levels will advance our understanding of this cancer critical circuit and more importantly, improve our ability to pharmacologically target the pathway in view of clonal development, tumor heterogeneity and drug resistance mechanisms. In this review, we revisit the PI3K/AKT pathway cancer susceptibility syndromes, summarize the known aberrations at the different regulatory levels and the prognostic and predictive values of these alterations in colorectal cancer.

Rectal Site and Suboptimal Nodal Yield Predict Systemic Recurrence in Resected Colorectal Carcinoma

We assessed the contribution of histopathological features to systemic recurrence (SR) in patients with colorectal cancer, using a case-control design: 71 cases and 184 controls were included, with a mean time until SR of 1.4 ± 0.1 years and a mean follow-up of controls of 1.6 ± 0.06 years. Cases had significantly greater odds of rectal site (odds ratio [OR] = 1.82), stage ≥pT3 (OR = 2.11), suboptimal (<12) lymph node yield (OR = 4.6), stage ≥pN1 (OR = 2.46), KRAS mutation (OR = 2.76), and extramural venous invasion (OR = 1.97). By multiple regression analysis, rectal site, stage ≥pT3, suboptimal lymph node yield, and lymph node positivity independently predicted SR. Rectal cancers were more likely to have a suboptimal node yield than nonrectal cancers (relative risk = 1.6) among the entire cohort. We conclude that rectal cancers have greater risk of SR than colon cancers. A lower yield of lymph nodes in rectal cancer specimens may contribute to this.

Prognostic value of CpG island methylator phenotype among colorectal cancer patients: a systematic review and meta-analysis

BACKGROUND

Divergent findings regarding the prognostic value of CpG island methylator phenotype (CIMP) in colorectal cancer (CRC) patients exist in current literature. We aim to review data from published studies in order to examine the association between CIMP and CRC prognosis.

MATERIALS AND METHODS

A comprehensive search for studies reporting disease-free survival (DFS), overall survival (OS), or cancer-specific mortality of CRC patients stratified by CIMP is carried out. Study findings are summarized descriptively and quantitatively, using adjusted hazard ratios (HRs) as summary statistics.

RESULTS

Thirty-three studies reporting survival in 10 635 patients are included for review. Nineteen studies provide data suitable for meta-analysis. The definition of CIMP regarding gene panel, marker threshold, and laboratory method varies across studies. Pooled analysis shows that CIMP is significantly associated with shorter DFS (pooled HR estimate 1.45; 95% confidence interval (CI) 1.07-1.97, Q = 3.95, I(2) = 0%) and OS (pooled HR estimate 1.43; 95% CI 1.18-1.73, Q = 4.03, I(2) = 0%) among CRC patients irrespective of microsatellite instability (MSI) status. Subgroup analysis of microsatellite stable (MSS) CRC patients also shows significant association between shorter OS (pooled HR estimate 1.37; 95% CI 1.12-1.68, Q = 4.45, I(2) = 33%) and CIMP. Seven studies have explored CIMP's value as a predictive factor on stage II and III CRC patient's DFS after receiving adjuvant 5-fluorouracil (5-FU) therapy: of these, four studies showed that adjuvant chemotherapy conferred a DFS benefit among CIMP(+) patients, one concluded to the contrary, and two found no significant correlation. Insufficient data was present for statistical synthesis of CIMP's predictive value among CRC patients receiving adjuvant 5-FU therapy.

CONCLUSION

CIMP is independently associated with significantly worse prognosis in CRC patients. However, CIMP's value as a predictive factor in assessing whether adjuvant 5-FU therapy will confer additional survival benefit to CRC patients remained to be determined through future prospective randomized studies.

Metachronous serrated neoplasia is uncommon after right colectomy in patients with methylator colon cancers with a high degree of microsatellite instability

BACKGROUND

Right-sided serrated polyps are precursors to sporadic microsatellite unstable colon cancers via the methylator pathway and have a high rate of synchronous and metachronous lesions. Serrated polyps also occur in Lynch syndrome, where right-sided microsatellite unstable cancers arise from germline mutations in mismatch repair genes.

OBJECTIVE

The aim of this study was to compare serrated neoplasia in patients with sporadic and hereditary microsatellite unstable colon cancer and to examine the effect of right colectomy on the risk of metachronous polyps and cancers.

DESIGN

This is a retrospective, descriptive, cohort study from database and chart review.

SETTING

This study was conducted at a tertiary care hospital with a center for hereditary colorectal cancer.

PATIENTS

Patients who had colon cancers with a high degree of microsatellite instability, methylator cancers, and Lynch syndrome cancers, were included.

INTERVENTIONS

Interventions included colectomy, surveillance colonoscopy, and polypectomy.

MAIN OUTCOME MEASURES

The primary outcomes measured were the incidence and location of metachronous polyps and cancers.

RESULTS

Eighty-five patients were included: 47 with methylator cancers and 38 with Lynch syndrome. Median ages at surgery were 75 years (range, 41-90) and 48 years (range, 27-77), p < 0.0001. Forty-six (98%) patients with methylator cancers and 17 (45%) patients with Lynch syndrome underwent a right colectomy, p < 0.0001. Metachronous cancers occurred in 19/60 (32%) of patients with Lynch syndrome and no patients with methylator cancers, p < 0.0001. Thirty-four patients with methylator cancers had colonoscopic follow-up, with a median of 2 colonoscopies per patient over a 32-month follow-up (range, 1-136). Sixty-three percent of patients with Lynch syndrome had colonoscopic follow-up, median of 4 colonoscopies per patient over 102 months (range, 1-462), p < 0.0001. Four (9%) patients with methylator cancers each had 1 metachronous serrated polyp, compared with 10/37 (27%) patients with Lynch syndrome (p = 0.049), whose median number of polyps was 2 (range, 1-8). Characteristics of other associated polyps were similar between cohorts.

LIMITATIONS

This study is somewhat limited by potential inherent bias from its retrospective design. Also, a high number of deaths in the CIMP+ cohort could have contributed to the low number of serrated polyps detected on colonoscopy surveillance, but given current understanding of serrated polyp growth, this may truly represent the left colon's tendency not to develop serrated polyps.

CONCLUSIONS

Cancers with a high degree of microsatellite instability arise through 2 different molecular mechanisms. Metachronous serrated neoplasia, benign and malignant, following right colectomy in patients with the CpG-island methylator phenotype of colorectal cancer is uncommon. However, the colons of patients with Lynch syndrome are at high risk after segmental colectomy.

Colonoscopy: what are we missing?

The purpose of most colonoscopies is to detect and treat colorectal neoplasia, preventing or providing early diagnosis of cancer. Basic to this mission is the recognition and diagnosis of neoplasms. Recent data suggest that detection of neoplasia during colonoscopy is suboptimal, resulting in a failure of screening colonoscopy as an efficient strategy for the prevention of cancer. In this article, the ramifications of these observations are examined and their relevance to the practice of colonoscopy considered.

The status of targeted agents in the setting of neoadjuvant radiation therapy in locally advanced rectal cancers

Radiotherapy has a longstanding and well-defined role in the treatment of resectable rectal cancer to reduce the historically high risk of local recurrence. In more advanced borderline or unresectable cases, where the circumferential resection margin (CRM) is breached or threatened according to magnetic resonance imaging (MRI), despite optimized local multimodality treatment and the gains achieved by modern high quality total mesorectal excision (TME), at least half the patients fail to achieve sufficient downstaging with current schedules. Many do not achieve an R0 resection. In less locally advanced cases, even if local control is achieved, this confers only a small impact on distant metastases and a significant proportion of patients (30-40%) still subsequently develop metastatic disease. In fact, distant metastases have now become the predominant cause of failure in rectal cancer. Therefore, increasing the intensity and efficacy of chemotherapy and chemoradiotherapy by integrating additional cytotoxics and biologically targetted agents seems an appealing strategy to explore-with the aim of enhancing curative resection rates and improving distant control and survival. However, to date, we lack validated biomarkers for these biological agents apart from wild-type KRAS. For cetuximab, the appearance of an acneiform rash is associated with response, but low levels of magnesium appear more controversial. There are no molecular biomarkers for bevacizumab. Although some less invasive clinical markers have been proposed for bevacizumab, such as circulating endothelial cells (CECS), circulating levels of VEGF and the development of overt hypertension, these biomarkers have not been validated and are observed to emerge only after a trial of the agent. We also lack a simple method of ongoing monitoring of 'on target' effects of these biological agents, which could determine and pre-empt the development of resistance, prior to radiological and clinical assessessments or even molecular imaging. These shortcomings probably explain our current relative lack of success in the arena of combining these agents with chemoradiation.

Clinical utility of KRAS and BRAF mutations in a cohort of patients with colorectal neoplasms submitted for microsatellite instability testing

BACKGROUND

Molecular analysis has become important in colorectal carcinoma (CRC) evaluation. Alterations in KRAS, BRAF, or mismatch repair (MMR) genes may determine therapeutic response or define a hereditary cancer syndrome. Correlation of DNA studies with clinical findings will further clarify the clinical utility of these markers.

PATIENTS AND METHODS

A retrospective study was performed on 111 paraffin-embedded tumor specimens submitted for microsatellite instability (MSI) testing based on clinical history or histologic examination, or both. DNA samples were screened for 7 KRAS mutations and the BRAF p.V600E mutation using fluorescent allele-specific polymerase-chain reaction (PCR) and capillary electrophoresis. Clinical data were collected through chart review.

RESULTS

Fifty-eight male and 53 female patients were studied. The incidence of KRAS and BRAF mutations was 49.5% and 7.2%, respectively. Dideoxy sequencing verified KRAS mutation status in 46 of 49 specimens tested. There was a trend toward significance of individual KRAS mutations on survival (P = .003). Dually positive KRAS and MSI tumors exclusively demonstrated p.G12D and p.G13D mutations (G>A transitions). BRAF-mutated tumors were predominantly right-sided and associated with a borderline worse prognosis. Forty-eight percent of tumors with MSI were present in the left colon or rectum.

CONCLUSION

Allele-specific PCR is an accurate and convenient method to assess KRAS and BRAF mutations and may detect mutations not identified by dideoxy sequencing. KRAS mutation status, in conjunction with morphologic or clinical parameters, may be useful in determining whether a tumor should be tested for MSI. MSI testing should not be considered exclusively in right-sided lesions. BRAF analysis may not be useful in rectal adenocarcinomas and should be evaluated in larger studies.

Molecular pathological epidemiology of epigenetics: emerging integrative science to analyze environment, host, and disease

Epigenetics acts as an interface between environmental/exogenous factors, cellular responses, and pathological processes. Aberrant epigenetic signatures are a hallmark of complex multifactorial diseases (including neoplasms and malignancies such as leukemias, lymphomas, sarcomas, and breast, lung, prostate, liver, and colorectal cancers). Epigenetic signatures (DNA methylation, mRNA and microRNA expression, etc) may serve as biomarkers for risk stratification, early detection, and disease classification, as well as targets for therapy and chemoprevention. In particular, DNA methylation assays are widely applied to formalin-fixed, paraffin-embedded archival tissue specimens as clinical pathology tests. To better understand the interplay between etiological factors, cellular molecular characteristics, and disease evolution, the field of 'molecular pathological epidemiology (MPE)' has emerged as an interdisciplinary integration of 'molecular pathology' and 'epidemiology'. In contrast to traditional epidemiological research including genome-wide association studies (GWAS), MPE is founded on the unique disease principle, that is, each disease process results from unique profiles of exposomes, epigenomes, transcriptomes, proteomes, metabolomes, microbiomes, and interactomes in relation to the macroenvironment and tissue microenvironment. MPE may represent a logical evolution of GWAS, termed 'GWAS-MPE approach'. Although epigenome-wide association study attracts increasing attention, currently, it has a fundamental problem in that each cell within one individual has a unique, time-varying epigenome. Having a similar conceptual framework to systems biology, the holistic MPE approach enables us to link potential etiological factors to specific molecular pathology, and gain novel pathogenic insights on causality. The widespread application of epigenome (eg, methylome) analyses will enhance our understanding of disease heterogeneity, epigenotypes (CpG island methylator phenotype, LINE-1 (long interspersed nucleotide element-1; also called long interspersed nuclear element-1; long interspersed element-1; L1) hypomethylation, etc), and host-disease interactions. In this article, we illustrate increasing contribution of modern pathology to broader public health sciences, which attests pivotal roles of pathologists in the new integrated MPE science towards our ultimate goal of personalized medicine and prevention.

Altered PTEN function caused by deletion or gene disruption is associated with poor prognosis in rectal but not in colon cancer

Colorectal cancer is the third most common malignancy worldwide. Anti-epidermal growth factor receptor (EGFR)-targeted therapy shows clinical evidence in this malignancy and improves outcome. The tumor suppressor gene phosphatase and tensin homologue (PTEN) is considered a potential predictor of nonresponse to anti-EGFR agents. The purpose of this study was to assess whether associations between PTEN alterations (PTEN gene deletion or PTEN gene disruption) and clinical outcome could be caused by a prognostic (and not predictive) effect of PTEN inactivation. Therefore, we analyzed 404 colorectal cancers not previously treated with anti-EGFR drugs in a tissue microarray format. PTEN deletion and PTEN gene rearrangements were analyzed by fluorescence in situ hybridization. Heterogeneity analysis of all available large tissue sections was performed in 6 cases with genomic PTEN alteration. Twenty-seven (8.8%) of 307 analyzable colorectal cancer spots showed genomic PTEN alterations including 24 hemizygous and 1 homozygous deletion as well as 2 PTEN gene disruptions. Genomic PTEN alterations were associated with reduced patient survival in rectal cancer in univariate and multivariate analyses (P = .012; hazard ratio, 2.675; 95% confidence interval, 1.242-5.759) but not in colon cancer. Large-section evaluation revealed a homogeneous distribution pattern in all 4 analyzed cases with PTEN deletion and in both cases with a PTEN gene disruption. In conclusion, genomic PTEN gene alterations caused by deletion or gene disruption characterize a fraction of rectal cancers with particularly poor outcome.

Cancers of the colon and rectum: identical or fraternal twins?

Colorectal cancer represents a major cause of cancer morbidity and mortality, with approximately 1.2 million cases and 600,000 deaths worldwide each year. Because of the anatomic continuity of the colon into the rectum, cancers affecting these organs have historically been considered equivalent. In this Prospective, we discuss the clinical and experimental data suggesting that colon cancer and rectal cancer are highly related, but distinct, diseases. Reconsidering the relationship between these cancers has implications for the development of new therapeutic paradigms.

Snaring large serrated polyps

BACKGROUND

Serrated polyps of the large bowel are potentially premalignant, difficult to see, but important to remove. Few studies describe the technique or outcomes of serrated polypectomy. We sought to present outcomes of a series of polypectomies of large serrated polyps in comparison to a series of endoscopic resections of large adenomas.

METHODS

This retrospective, comparative, single endoscopist study was performed in an outpatient colonoscopy department of a tertiary referral medical center. Patients had outpatient colonoscopy where a large (≥2 cm) serrated polyp or adenoma was removed. Outcomes were completeness of excision and complications of polypectomy. A database of endoscopic polypectomies was reviewed. Polypectomy of large serrated polyps was compared with polypectomy of large adenomas.

RESULTS

There were 132 large serrated polyps in 112 patients and 563 adenomas in 428 patients. More serrated polyps were right sided (120 of 130, 92.3 %, vs. 379 of 563, 67 %) (p < 0.0001). The serrated polyps were smaller than the adenomas (mean 25.5 ± 7.9 mm standard deviation) versus 36.8 ± 16.9 mm standard deviation (p < 0.001). There were four complications of serrated polypectomy in four patients (4 % of polyps, 5 % of patients): three postpolypectomy bleeds and one postpolypectomy syndrome. There were 33 complications of adenoma removal (31 postpolypectomy bleeding and two postpolypectomy syndrome) (6.9 % of polyps, p = 0.376, 8.4 % of patients, p = 0.371). On follow-up, 36 of 51 patients (71 %) with serrated polyps had metachronous lesions compared to 133 of 298 patients (45 %) with adenomas (p < 0.0001). There were fewer residual polyps in the serrated group (4 of 47 vs. 64 of 298, p = 0.001).

CONCLUSIONS

Removal of large serrated colorectal polyps is no more complicated than polypectomy of similarly sized adenomas. However, large serrated polyps have a higher rate of metachronous polyps than similarly sized adenomas and surveillance should be adapted to reflect these findings.

Cancer vaccines: should we be targeting patients with less aggressive disease?

There is enthusiasm for using vaccines to stimulate the immune system to treat cancer. In this article, the authors review the evolution of vaccines evaluated in clinical trials, starting with Phase III trials in metastatic disease and progressing to trials in the adjuvant setting. Data from these trials suggest that cancer vaccines may be more effective in patients with lower volume disease, and data from the E75 peptide vaccine trials suggest that vaccines may be most effective in less aggressive disease.

Serrated polyps: new classifications highlight clinical importance

AIM

Many lesions previously classified as hyperplastic polyps and therefore thought to be innocuous have been reclassified as sessile serrated adenomas/polyps (SSA/Ps), establishing their place in the serrated pathway and underscoring their malignant potential. The clinical relevance of this new nomenclature is incompletely defined. This study examines the incidence and characteristics of colorectal SSA/Ps and describes other associated colorectal neoplasia.

METHOD

A single institution pathology database was searched for the diagnosis of SSA/Ps between January 2004 and October 2007. SSA/Ps found by colonoscopy were included. Patient demographics, SSA/P characteristics and associated colonoscopic findings were retrospectively recorded.

RESULTS

A total of 585 SSA/Ps were removed during 519 colonoscopies in 483 patients performed by 64 different endoscopists. This represented an overall incidence of SSA/Ps per colonoscopy of 2.1% in the 28,054 colonoscopies performed during the study period. The median SSA/P size was 0.8 cm (range 0.2-4.5) and 188 (69%) were ≥ 1.0 cm. Of the 585 SSA/Ps, 366 (63%) were right-sided, 129 (22%) were in the left colon and 90 (15%) were in the rectum. Also, 439 synchronous polyps of other histology (mainly adenomas and hyperplastic polyps) were found during the same 519 colonoscopies.

CONCLUSION

SSA/Ps are rare lesions found during colonoscopy that may coexist with small hyperplastic polyps. Because SSA/Ps are part of the serrated oncogenic pathway, all, even those appearing to be hyperplastic, should be removed or biopsied for diagnosis. Careful review of historical lesions with application of new definitions may redefine risk for malignancy.

Fish consumption and colorectal cancer risk in humans: a systematic review and meta-analysis

BACKGROUND

Fish consumption may protect against colorectal cancer, but results from observational studies are inconsistent; therefore, a systematic review with a meta-analysis was conducted.

METHODS

Relevant studies were identified by a search of MEDLINE and EMBASE databases to May 2011, with no restrictions. Reference lists from retrieved articles also were reviewed. Studies that reported odds ratio (OR) or relative risk estimates with 95% confidence intervals (CIs) for the association between the consumption of fish and the risk of colorectal, colon, or rectal cancer were included. Two authors independently extracted data and assessed study quality. The risk estimate (hazard ratio, relative risk, or OR) of the highest and lowest reported categories of fish intake were extracted from each study and analyzed using a random-effects model.

RESULTS

Twenty-two prospective cohort and 19 case-control studies on fish consumption and colorectal cancer risk met the inclusion criteria and were included in the meta-analysis. Our analysis found that fish consumption decreased the risk of colorectal cancer by 12% (summary OR, 0.88; 95% CI, 0.80-0.95). The pooled ORs of colorectal cancer for the highest versus lowest fish consumption in case-control studies and cohort studies were 0.83 (95% CI, 0.72-0.95) and 0.93 (95% CI, 0.86-1.01), respectively. There was heterogeneity among case-control studies (P<.001) but not among cohort studies. A significant inverse association was found between fish intake and rectal cancer (summary OR, 0.79; 95% CI, 0.65-0.97), and there was a modest trend seen between fish consumption and colon cancer (summary OR, 0.96; 95% CI, 0.81-1.14). This study had no publication bias.

CONCLUSION

Our findings from this meta-analysis suggest that fish consumption is inversely associated with colorectal cancer.

High-throughput arrays identify distinct genetic profiles associated with lymph node involvement in rectal cancer

BACKGROUND

Preoperative clinical diagnosis of lymph node involvement guides treatment decisions for rectal cancer. Unfortunately, clinical staging still suffers from a lack of accuracy.

OBJECTIVE

The aim of this study was to evaluate objective genetic differences in primary rectal cancers with and without associated lymph node metastasis.

DESIGN

cDNA microarrays were generated from fresh-frozen tumors. Normalized data underwent global unsupervised hierarchical clustering analysis, and discriminating genes were mapped. Top discriminating genes were compared between stage II and III rectal cancers by use of an empirical Bayes 2 group t test with the Statistical Analysis of Microarrays and the Reproducibility-Optimized Test Statistic software separately to guide data reduction and deal with the difficulties of simultaneous statistical inference. Ingenuity Pathways Analysis software was used to analyze discriminating genes in terms of function and biological processes.

PATIENTS

Fifty-five patients with stage II and 22 patients with stage III rectal adenocarcinomas not treated with chemoradiation were included.

RESULTS

Two major unsupervised clusters emerged representing stage II and III cancers. In 1 cluster, 11 of 12 patients (92%) had stage III cancer; in the other cluster, 54 of 65 patients (83%) had stage II (p < 0.001). Five significantly differentially expressed genes characterized the stage III cluster: interleukin-8, 3-hydroxy-3-methylglutaryl coenzyme A synthase, carbonic anhydrase, ubiquitin, and cystatin (all p < 0.05). Of the 12 patients with differential expression of the 5 marker genes, only one had stage II cancer. Fifty-four of 55 stage II patients clustered with alternative expression patterns of the predictor genes. Differentially expressed genes are related to cancer-associated processes, pathways, and networks.

LIMITATIONS

The identified gene signatures have not yet been validated in independent patient populations.

CONCLUSIONS

Distinct gene expression signatures from primary rectal adenocarcinomas can help differentiate the presence or absence of lymph node metastases. These data are informative, and validation of this gene signature may provide a novel approach for more appropriate individualized treatment selection.

BRAF mutations in colorectal cancer are associated with distinct clinical characteristics and worse prognosis

BACKGROUND

Colorectal cancer is a heterogeneous disease with multiple underlying genetic mutations causing different clinical phenotypes. Mutation in the BRAF oncogene is a key step in malignant transformation within the methylator pathway to colorectal cancer. However, there is a paucity of information about BRAF mutant colorectal tumors.

OBJECTIVE

This study defines the clinical characteristics and oncologic outcome associated with colorectal cancer BRAF mutations.

DESIGN

Colorectal adenocarcinomas from a single-institution frozen-tumor biobank were studied. Genomic DNA was isolated and analyzed for mutations in the BRAF oncogene by polymerase chain reaction amplification followed by direct sequencing. A sample was classified as mutant if any of the tested loci were mutated. Patient and tumor characteristics were recorded including patient age, sex, tumor location, tumor differentiation, and microsatellite instability.

MAIN OUTCOME MEASURES

Statistical associations with BRAF mutant tumors were determined by the Fisher exact probability test, χ test, or Wilcoxon analysis. Kaplan-Meier estimates and multivariate Cox regression analysis were performed for overall survival.

RESULTS

Four hundred seventy-five colorectal adenocarcinomas were included in the study population; 56 samples harbored a BRAF mutation (12%). There were significant differences between BRAF wild-type and mutant tumors in age (66 vs 75 years, p = 0.004), female sex (44% vs 71%, p < 0.001), proximal tumor location (44% vs 95%, p < 0.001), and frequency of microsatellite instability (16% vs 76%, p < 0.001). There was no difference in cancer stage between BRAF mutant and wild-type populations. Survival data were analyzed for 322 patients with stage I to III disease, and patients with a BRAF mutation had decreased overall survival than those without a mutation (p = 0.018). With the use of Cox regression analysis, BRAF mutation conferred a worse overall survival (HR 1.79, CI 1.05-3.05, p = 0.03) independent of microsatellite instability status.

CONCLUSIONS

BRAF mutations in colorectal cancers are associated with distinct clinical characteristics and worse prognosis.

Predictive and prognostic roles of BRAF mutation in stage III colon cancer: results from intergroup trial CALGB 89803

PURPOSE

Alterations in the RAS-RAF-MAP2K (MEK)-MAPK signaling pathway are major drivers in colorectal carcinogenesis. In colorectal cancer, BRAF mutation is associated with microsatellite instability (MSI), and typically predicts inferior prognosis. We examined the effect of BRAF mutation on survival and treatment efficacy in patients with stage III colon cancer.

METHODS

We assessed status of BRAF c.1799T>A (p.V600E) mutation and MSI in 506 stage III colon cancer patients enrolled in a randomized adjuvant chemotherapy trial [5-fluorouracil and leucovorin (FU/LV) vs. irinotecan (CPT11), FU and LV (IFL); CALGB 89803]. Cox proportional hazards model was used to assess the prognostic role of BRAF mutation, adjusting for clinical features, adjuvant chemotherapy arm, and MSI status.

RESULTS

Compared with 431 BRAF wild-type patients, 75 BRAF-mutated patients experienced significantly worse overall survival [OS; log-rank P = 0.015; multivariate HR = 1.66; 95% CI: 1.05-2.63]. By assessing combined status of BRAF and MSI, it seemed that BRAF-mutated MSS (microsatellite stable) tumor was an unfavorable subtype, whereas BRAF wild-type MSI-high tumor was a favorable subtype, and BRAF-mutated MSI-high tumor and BRAF wild-type MSS tumor were intermediate subtypes. Among patients with BRAF-mutated tumors, a nonsignificant trend toward improved OS was observed for IFL versus FU/LV arm (multivariate HR = 0.52; 95% CI: 0.25-1.10). Among patients with BRAF wild-type cancer, IFL conferred no suggestion of benefit beyond FU/LV alone (multivariate HR = 1.02; 95% CI: 0.72-1.46).

CONCLUSIONS

BRAF mutation is associated with inferior survival in stage III colon cancer. Additional studies are necessary to assess whether there is any predictive role of BRAF mutation for irinotecan-based therapy.

Tumor location determines midkine level and its association with the disease progression in colorectal cancer patients: a pilot study

PURPOSE

The purpose of this study was to evaluate midkine, multipotential cytokine, and growth factor in colorectal cancer (CRC) stratified by tumor location.

METHODS

Midkine was assessed immunoenzymatically in paired cancerous and noncancerous tissues from 53 CRCs and referred to CRC stage, tumor location, and size, and circulating cytokine levels.

RESULTS

Midkine was higher in cancerous versus noncancerous tissue in 98 % cases (424.2 vs. 31.1 pg/mg, p < 0.0001). Mean fold increase was 30.1; in 72.5 %, the relative increase was over fivefold. Midkine upregulation was more pronounced in colon than in rectum (fold increase: 36.6 vs. 12.7, p = 0.005) due to higher midkine level in noncancerous rectal than colonic tissue (45.5 vs. 26.2 pg/mg, p = 0.074). Tumor location affected midkine association with CRC stage. Midkine fold change was higher in advanced stages of rectal cancers (16.8 vs. 5.3, respectively in III/IV vs. I/II, p = 0.013), while it tended to be lower in colonic ones (25.3 vs. 47.8, p = 0.134). In addition, fold change in midkine level was higher in rectal N1 than N0 cancers (17.3 vs. 16.5, p = 0.032), while it tended to be lower in colonic cancers (23.6 vs. 50.1, p = 0.085). Midkine negatively correlated with tumor size (r = 0.40, p = 0.017), while it tended to positively correlate with its serum levels (r = 0.45, p = 0.081).

CONCLUSIONS

Midkine is differently expressed in tumors arising from colonic and rectal mucosa, where it may play diverse roles in carcinogenesis. High midkine expression in noncancerous rectal mucosa might contribute to, a characteristic for rectal cancers, higher incidence of local recurrence. Divergent expression of midkine and its association pattern ought to be taken into account while designing midkine-directed therapies for CRC.

Phospho-ERK and AKT status, but not KRAS mutation status, are associated with outcomes in rectal cancer treated with chemoradiotherapy

BACKGROUND

KRAS mutations may predict poor response to radiotherapy. Downstream events from KRAS, such as activation of BRAF, AKT and ERK, may also confer prognostic information but have not been tested in rectal cancer (RC). Our objective was to explore the relationships of KRAS and BRAF mutation status with p-AKT and p-ERK and outcomes in RC.

METHODS

Pre-radiotherapy RC tumor biopsies were evaluated. KRAS and BRAF mutations were assessed by pyrosequencing; p-AKT and p-ERK expression by immunohistochemistry.

RESULTS

Of 70 patients, mean age was 58; 36% stage II, 56% stage III, and 9% stage IV. Responses to neoadjuvant chemoradiotherapy: 64% limited, 19% major, and 17% pathologic complete response. 64% were KRAS WT, 95% were BRAF WT. High p-ERK levels were associated with improved OS but not for p-AKT. High levels of p-AKT and p-ERK expression were associated with better responses. KRAS WT correlated with lower p-AKT expression but not p-ERK expression. No differences in OS, residual disease, or tumor downstaging were detected by KRAS status.

CONCLUSIONS

KRAS mutation was not associated with lesser response to chemoradiotherapy or worse OS. High p-ERK expression was associated with better OS and response. Higher p-AKT expression was correlated with better response but not OS.