Association of serum superoxide dismutase activity and the incidence of colorectal cancer in a nested case-control study

BACKGROUND

Superoxide dismutase (SOD) is an antioxidant enzyme that degrades superoxide, a major causative factor in carcinogenesis. We assessed associations between serum SOD activities and incidence of colorectal carcinoma (CRC) in a case-control study nested in the Japan Collaborative Cohort (JACC) study.

METHODS

At baseline, 39,242 subjects donated serum samples. Participants diagnosed with CRC during follow-up were regarded as cases. Odds ratios (ORs) for CRC incidence associated with SOD were evaluated with conditional logistic regression models. In the current study, 176 cases and 524 controls were analyzed.

RESULTS

For the overall cohort, a decreasing trend in risk of CRC with increasing SOD was observed (P for trend=0.054) and the fourth quartile of SOD level showed the lowest risk compared to the first (OR=0.52, 95% confidence interval [CI]=0.29-0.93). This was significant in men (P for trend=0.001), with the fourth quartile of SOD level showing the lowest risk compared to the first (OR, 0.23; 95%CI, 0.09-0.60). It was also exclusively observed for rectal cancer and left-sided CRC (P for trend, 0.037 and 0.020, respectively), with the fourth quartile again showing the lowest risk compared to the first (OR, 0.28 and 0.38; 95%CI, 0.09-0.84 and 0.16-0.91, respectively). Limiting subjects to those followed-up over 2 years, all trends remained unchanged.

CONCLUSIONS

Our findings suggest that serum SOD activity correlates inversely with risk of CRC, particularly in men and individuals with rectal cancer/left-sided CRC.

Prognostic value of primary tumor location in colorectal cancer: an updated meta-analysis

The clinical, histological, and molecular differences between right-sided colon cancer (RCC) and left-sided colon cancer (RCC) have received considerable attention. Over the past decade, many articles have been published concerning the association between primary tumor location (PTL) of colorectal cancer and survival outcomes. Therefore, there is a growing need for an updated meta-analysis integrating the outcomes of recent studies to determine the prognostic role of right vs left-sidedness of PTL in patients with colorectal cancer. We conducted a comprehensive database review using PubMed, SCOPUS, and Cochrane library databases from February 2016 to March 2023 for prospective or retrospective studies reporting data on overall survival (OS) and cancer-specific survival (CSS) of RCC compared with LCC. A total of 60 cohort studies comprising 1,494,445 patients were included in the meta-analysis. We demonstrated that RCC is associated with a significantly increased risk of death compared with LCC by 25% (hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.19-1.31; I2 = 78.4%; Z = 43.68). Results showed that patients with RCC have a worse OS compared with LCC only in advanced stages (Stage III: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%; Stage IV: HR, 1.34; 95% CI 1.25-1.44; P < 0.0001; I2 = 69.2%) but not in primary stages (Stage I/II: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%). Moreover, a meta-analysis of 13 studies including 812,644 patients revealed that there is no significant difference in CSS between RCC and LCC (HR, 1.121; 95% CI 0.97-1.3; P = 0.112). Findings from the present meta-analysis highlight the importance of PTL in clinical decision-making for patients with CRC, especially in advanced stages. We provide further evidence supporting the hypothesis that RCC and LCC are distinct disease entities that should be managed differently.

Development and validation of prognostic nomograms for early-onset colon cancer in different tumor locations: a population-based study

OBJECTIVE

The prevalence of early-onset colon cancer (EOCC) among individuals below the age of 50 has shown a marked upward trend in recent years. The embryology, clinical symptoms, incidence, molecular pathways, and oncologic outcomes differ between right-sided and left-sided colon cancers. However, the differences have not been fully researched in EOCC. Our study aims to develop and validate prognostic nomograms predicting overall survival (OS) and cancer-specific survival (CSS) for EOCC in different tumor locations based on the Surveillance, Epidemiology, and End Results (SEER) database.

METHODS

Using the SEER database, a total of 5,588 patients with EOCC were extracted and divided into development and validation cohorts in a random allocation ratio of 7:3 across three groups. Univariate and multivariate Cox regression analyses were performed to identify independent prognostic factors influencing OS and CSS outcomes. These factors were then utilized to construct nomogram models. The prognostic capabilities of the three models were assessed through various evaluation metrics, including the concordance index (C-index), receiver operating characteristic (ROC) curves, calibration curves, decision curve analysis (DCA), and validation cohorts respectively. Additionally, survival curves of the low- and high-risk groups were calculated using the Kaplan-Meier method together with the log-rank test.

RESULTS

Significant differences in clinical features were observed between right-sided and left-sided EOCCs, particularly in terms of OS (52 months vs 54 months) as demonstrated by Kaplan-Meier curves. Transverse-sided EOCCs exhibited clinical characteristics similar to right-sided EOCCs, suggesting a potential shared tumor microenvironment and therapeutic considerations. Advanced stage, liver metastasis, poor grade, elevated pretreatment carcinoembryonic antigen (CEA) level, chemotherapy, and perineural invasion were identified as independent prognostic factors across all three tumor locations and were incorporated into the nomogram model. Nomograms were constructed to predict the probability of 3- and 5-year OS and CSS. The C-index and calibration plots showed that the established nomograms had good consistency between actual clinical observations and predicted outcomes. ROC curves with calculated area under the curve (AUC) values exceeded 0.8 for all three groups in both the development and validation cohorts, indicating robust predictive performance for OS and CSS. Furthermore, decision curve analysis (DCA) plots revealed a threshold probability range of 0.1 to 0.9, within which the nomogram model exhibited maximum benefit. Kaplan-Meier curves exhibited significant differences between the low- and high-risk groups in EOCC for all three tumor locations in OS and CSS, further validating the prognostic value of the nomogram models.

CONCLUSIONS

We successfully developed three precise nomogram models for EOCCs in different tumor locations, providing valuable support for clinicians in guiding clinical treatments and facilitating further prospective follow-up studies.

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

INTRODUCTION

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

METHODOLOGY

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

RESULTS

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

CONCLUSIONS

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

Identifying important microbial and genomic biomarkers for differentiating right- versus left-sided colorectal cancer using random forest models

BACKGROUND

Colorectal cancer (CRC) is a heterogeneous disease, with subtypes that have different clinical behaviours and subsequent prognoses. There is a growing body of evidence suggesting that right-sided colorectal cancer (RCC) and left-sided colorectal cancer (LCC) also differ in treatment success and patient outcomes. Biomarkers that differentiate between RCC and LCC are not well-established. Here, we apply random forest (RF) machine learning methods to identify genomic or microbial biomarkers that differentiate RCC and LCC.

METHODS

RNA-seq expression data for 58,677 coding and non-coding human genes and count data for 28,557 human unmapped reads were obtained from 308 patient CRC tumour samples. We created three RF models for datasets of human genes-only, microbes-only, and genes-and-microbes combined. We used a permutation test to identify features of significant importance. Finally, we used differential expression (DE) and paired Wilcoxon-rank sum tests to associate features with a particular side.

RESULTS

RF model accuracy scores were 90%, 70%, and 87% with area under curve (AUC) of 0.9, 0.76, and 0.89 for the human genomic, microbial, and combined feature sets, respectively. 15 features were identified as significant in the model of genes-only, 54 microbes in the model of microbes-only, and 28 genes and 18 microbes in the model with genes-and-microbes combined. PRAC1 expression was the most important feature for differentiating RCC and LCC in the genes-only model, with HOXB13, SPAG16, HOXC4, and RNLS also playing a role. Ruminococcus gnavus and Clostridium acetireducens were the most important in the microbial-only model. MYOM3, HOXC4, Coprococcus eutactus, PRAC1, lncRNA AC012531.25, Ruminococcus gnavus, RNLS, HOXC6, SPAG16 and Fusobacterium nucleatum were most important in the combined model.

CONCLUSIONS

Many of the identified genes and microbes among all models have previously established associations with CRC. However, the ability of RF models to account for inter-feature relationships within the underlying decision trees may yield a more sensitive and biologically interconnected set of genomic and microbial biomarkers.

Robotic versus laparoscopic left colectomy with complete mesocolic excision for left-sided colon cancer: a multicentre study with propensity score matching analysis

PURPOSE

Robotic surgery for right-sided colon and rectal cancer has rapidly increased; however, there is limited evidence in the literature of advantages of robotic left colectomy (RLC) for left-sided colon cancer. The purpose of this study was to compare the outcomes of RLC versus laparoscopic left colectomy (LLC) with complete mesocolic excision (CME) for left-sided colon cancer.

METHODS

Patients who had RLC or LLC with CME for left-sided colon cancer at five hospitals in China between January 2014 and April 2022 were included. A one-to-one propensity score matched analysis was performed to decrease confounding. The primary outcome was postoperative complications occurring within 30 days of surgery. Secondary outcomes were disease-free survival, overall survival and the number of harvested lymph nodes.

RESULTS

A total of 292 patients (187 male; median age 61.0 [20.0-85.0] years) were eligible for this study, and propensity score matching yielded 102 patients in each group. The clinicopathological characteristics were well-matched between groups. The two groups did not differ in estimated blood loss, conversion to open rate, time to first flatus, reoperation rate, or postoperative length of hospital stay (p > 0.05). RLC was associated with a longer operation time (192.9 ± 53.2 vs. 168.9 ± 52.8 min, p = 0.001). The incidence of postoperative complications did not differ between the RLC and LLC groups (18.6% vs. 17.6%, p = 0.856). The total number of lymph nodes harvested in the RLC group was higher than that in the LLC group (15.7 ± 8.3 vs. 12.1 ± 5.9, p < 0.001). There were no significant differences in 3-year and 5-year overall survival or 3-year and 5-year disease-free survival.

CONCLUSION

Compared to laparoscopic surgery, RLC with CME for left-sided colon cancer was found to be associated with higher numbers of lymph nodes harvested and similar postoperative complications and long-term survival outcomes.

Robotic versus laparoscopic left colectomy with complete mesocolic excision for left-sided colon cancer: a multicentre study with propensity score matching analysis

BACKGROUND

Robotic surgery for right-sided colon and rectal cancer has rapidly increased; however, there is limited evidence in the literature of advantages of robotic left colectomy (RLC) for left-sided colon cancer. The purpose of this study was to compare the outcomes of RLC versus laparoscopic left colectomy (LLC) with complete mesocolic excision (CME) for left-sided colon cancer.

METHODS

Patients who had RLC or LLC with CME for left-sided colon cancer at 5 hospitals in China between January 2014 and April 2022 were included. A one-to-one propensity score matched analysis was performed to decrease confounding. The primary outcome was postoperative complications occurring within 30 days of surgery. Secondary outcomes were disease-free survival, overall survival and the number of harvested lymph nodes.

RESULTS

A total of 292 patients (187 males; median age 61.0 [20.0-85.0] years) were eligible for this study, and propensity score matching yielded 102 patients in each group. The clinical-pathological characteristics were well-matched between groups. The two groups did not differ in estimated blood loss, conversion to open rate, time to first flatus, reoperation rate, or postoperative length of hospital stay (p > 0.05). RLC was associated with a longer operation time (192.9 ± 53.2 vs. 168.9 ± 52.8 minutes, p=0.001). The incidence of postoperative complications did not differ between the RLC and LLC groups (18.6% vs. 17.6%, p = 0.856). The total number of lymph nodes harvested in the RLC group was higher than that in the LLC group (15.7 ± 8.3 vs. 12.1 ± 5.9, p< 0.001). There were no significant differences in 3-year and 5-year overall survival or 3-year and 5-year disease-free survival.

CONCLUSIONS

Compared to laparoscopic surgery, RLC with CME for left-sided colon cancer was found to be associated with higher numbers of lymph nodes harvested and similar postoperative complications and long-term survival outcomes.

Clinical outcomes of laparoscopic-assisted natural orifice specimen extraction colectomy using a Cai tube for left-sided colon cancer: a prospective randomized trial

BACKGROUND

The role of laparoscopic-assisted natural orifice specimen extraction (LA-NOSE) colectomy in the treatment of left-sided colon cancer has not been well defined, and there remains confusion about how to conveniently exteriorize specimens through natural orifices. Therefore, we introduced a homemade invention, the Cai tube, to facilitate the extraction of specimens and compared the clinical outcomes of LA-NOSE with conventional laparoscopic (CL) colectomy for left-sided colon cancer.

METHODS

From March 2015 to August 2017, patients with left-sided colon cancer were randomly divided into LA-NOSE and CL groups. Specimens were extracted through the anus with the help of a Cai tube (Patent Number: ZL201410168748.2) in the LA-NOSE group. The primary outcome measure was postoperative pain. Secondary outcomes were the duration of operation, postoperative recovery, surgical morbidity, pathological quality of the specimen, and long-term outcomes, including 3-year overall survival, disease-free survival, local recurrence, and overall recurrence.

RESULTS

A total of 60 patients (30 per group) were recruited for this study. None of the patients required emergency conversion to conventional laparoscopic or open surgery during the operation. The postoperative maximum pain score was significantly lower in the LA-NOSE group (mean 2.5 vs. 5.1, P = 0.001), as was the additional analgesia requirement (mean 2/30 vs. 10/30, P = 0.021). Patients in the LA-NOSE group experienced a shorter first time to passage of flatus (mean 2.2 vs. 3.1 days, P = 0.026). All patients could control their defecation at 6 months after surgery. The comparison between the two groups showed no significant differences in the operative time, bleeding volume, postoperative hospital stay, surgical morbidity rates, number of lymph nodes harvested, or resection margin status. The mean follow-up was 48 months (range 7-59) and was similar in both groups. The results showed no differences in long-term outcomes between the two groups.

CONCLUSION

In the treatment of left-sided colon cancer, compared with conventional laparoscopic colectomy, LA-NOSE colectomy using the Cai tube exhibited lower postoperative pain, shorter recovery of gastrointestinal function, and similar long-term outcomes.

REGISTRATION NUMBER

ChiCTR-OOR-15007060 ( http://www.chictr.org.cn/ ).

Discovering the molecular differences between right- and left-sided colon cancer using machine learning methods

Background

In recent years, the differences between left-sided colon cancer (LCC) and right-sided colon cancer (RCC) have received increasing attention due to the clinicopathological variation between them. However, some of these differences have remained unclear and conflicting results have been reported.

Methods

From The Cancer Genome Atlas (TCGA), we obtained RNA sequencing data and gene mutation data on 323 and 283 colon cancer patients, respectively. Differential analysis was firstly done on gene expression data and mutation data between LCC and RCC, separately. Machine learning (ML) methods were then used to select key genes or mutations as features to construct models to classify LCC and RCC patients. Finally, we conducted correlation analysis to identify the correlations between differentially expressed genes (DEGs) and mutations using logistic regression (LR) models.

Results

We found distinct gene mutation and expression patterns between LCC and RCC patients and further selected the 30 most important mutations and 17 most important gene expression features using ML methods. The classification models created using these features classified LCC and RCC patients with high accuracy (areas under the curve (AUC) of 0.8 and 0.96 for mutation and gene expression data, respectively). The expression of PRAC1 and BRAF V600E mutation (rs113488022) were the most important feature for each model. Correlations of mutations and gene expression data were also identified using LR models. Among them, rs113488022 was found to have significance relevance to the expression of four genes, and thus should be focused on in further study.

Conclusions

On the basis of ML methods, we found some key molecular differences between LCC and RCC, which could differentiate these two groups of patients with high accuracy. These differences might be key factors behind the variation in clinical features between LCC and RCC and thus help to improve treatment, such as determining the appropriate therapy for patients.

Impact of Primary Tumor Location on Survival After Curative Resection in Patients with Colon Cancer: A Meta-Analysis of Propensity Score-Matching Studies

BACKGROUND

Recent retrospective subgroup analyses of patients with unresectable colon cancer (CC) receiving systemic chemotherapy have demonstrated that there is a significant difference in treatment outcome between patients with right-sided CC (RSCC) and those with left-sided CC (LSCC). However, it is impossible to divide patients with CC randomly into RSCC and LSCC groups before surgery. Therefore, the aim of this study is to explore the impact of primary tumor location (PTL) on survival after curative surgery for patients with CC using propensity score-matching (PSM) studies instead of randomization.

MATERIALS AND METHODS

We performed a comprehensive electronic search of the literature up to January 2019 to identify studies that had used databases allowing comparison of postoperative survival between patients with RSCC and those with LSCC. To integrate the impact of PTL on 5-year overall survival (OS) after curative surgery, a meta-analysis was performed using random-effects models to calculate the risk ratio (RR) and 95% confidence interval (CI) for the selected PSM studies.

RESULTS

Five studies involving a total of 398,687 patients with CC were included in this meta-analysis. Among 205,641 patients with RSCC, 69,091 (33.6%) died during the observation period, whereas among 193,046 patients with LSCC, 63,380 (32.8%) died during the same period. These results revealed that patients with RSCC and those with LSCC had almost the same 5-year OS (RR, 0.98; 95% CI, 0.89-1.07; p = .64; I² = 97%).

CONCLUSION

This meta-analysis has demonstrated that there was no significant difference in 5-year OS between patients with RSCC and those with LSCC after curative resection.

IMPLICATIONS FOR PRACTICE

To integrate the impact of primary tumor location (PTL) on 5-year overall survival (OS) after curative surgery, five propensity score-matching (PSM) studies involving a total of 398,687 patients with colon cancer (CC) were included in this meta-analysis. Among 205,641 patients with right-sided CC (RSCC), 69,091 (33.6%) died during the observation period, whereas among 193,046 patients with left-sided CC (LSCC), 63,380 (32.8%) died during the same period. These results revealed that patients with RSCC and those with LSCC had almost the same 5-year OS (risk ratio, 0.98; 95% confidence interval, 0.89-1.07; p = .64; I² = 97%).

Prognostic impact of primary tumor location in Stage III colorectal cancer-right-sided colon versus left-sided colon versus rectum: a nationwide multicenter retrospective study

BACKGROUND

Previous studies investigating the impact of tumor location on colorectal cancer prognosis only compared two groups by location, e.g., 'right-sided colon vs. left-sided colon,' 'colon vs. rectum,' and 'right-sided (right-sided colon) vs. left-sided (left-sided colon and rectum).' This nationwide multicenter retrospective study aimed to clarify the prognostic impact of tumor location in patients with stage III colorectal cancer by classifying tumors into three groups: right-sided colon, left-sided colon, and rectum.

METHODS

Subjects were 9194 patients with stage III colorectal cancer who underwent curative surgery from 1997 to 2012. Relapse-free survival (RFS) after primary surgery and overall survival (OS) after recurrence were examined.

RESULTS

Rectal cancer (n = 2922) was associated with worse RFS compared to right-sided colon cancer (n = 2362) (hazard ratio (HR) 0.65; 95% CI 0.59-0.72; p < 0.001) and left-sided colon cancer (n = 3910) (HR 0.72; 95% CI 0.66-0.78; p < 0.001) after adjusting for key clinical factors (i.e., sex, age, histological type, CEA, adjuvant therapy, T category, and N category). Among patients with recurrence (n = 2823), rectal cancer was associated with better OS compared to right-sided colon cancer (HR 1.23; 95% CI 1.08-1.40; p = 0.002) and worse OS compared to left-sided colon cancer (HR 0.88; 95% CI 0.79-0.99; p = 0.029). Twenty percent of right-sided colon cancer recurrences exhibited peritoneal dissemination, 42% of left-sided colon cancer recurrences were liver metastases, and 33% of rectal cancer recurrences were local recurrences.

CONCLUSIONS

The three tumor locations (right-sided colon, left-sided colon, rectum) had different prognostic implications for recurrence after curative resection and overall mortality, suggesting that tumor location serves as a prognostic biomarker in stage III colorectal cancer.

Right and left-sided colon cancers - specificity of molecular mechanisms in tumorigenesis and progression

Background

Given the differences in embryonic origin, vascular and nervous supplies, microbiotic burden, and main physiological functions of left and right colons, tumor location is increasingly suggested to dictate tumor behavior affecting pathology, progression and prognosis. Right-sided colon cancers arise in the cecum, ascending colon, hepatic flexure and/or transverse colon, while left-sided colon cancers arise in the splenic flexure, descending, and/or sigmoid colon. In contrast to prior reports, we attempt to delineate programs of tumorigenesis independently for each side.

Methods

Four hundred and eleven samples were extracted from The Cancer Genome Atlas-COAD cohort, based on a conservative sample inclusion criterion. Each side was independently analyzed with respect to their respective normal tissue, at the level of transcription, post-transcription, miRNA control and methylation in both a stage specific and stage-agnostic manner.

Results

Our results indicate a suppression of enzymes involved in various stages of carcinogen breakdown including CYP2C8, CYP4F12, GSTA1, and UGT1A within right colon tumors. This implies its reduced capacity to detoxify carcinogens, contributing to a genotoxic tumor environment, and subsequently a more aggressive phenotype. Additionally, we highlight a crucial nexus between calcium homeostasis (sensing, mobilization and absorption) and immune/GPCR signaling within left-sided tumors, possibly contributing to its reduced proliferative and metastatic potential. Interestingly, two genes SLC6A4 and HOXB13 show opposing regulatory trends within right and left tumors. Post-transcriptional regulation mediated by both RNA-binding proteins (e.g. NKRF (in left) and MSI2 (in right)) and miRNAs (e.g. miR-29a (in left); miR-155, miR181-d, miR-576 and miR23a (in right)) appear to exhibit side-specificity in control of their target transcripts and is pronounced in right colon tumors. Additionally, methylation results depict location-specific differences, with increased hypomethylation in open seas within left tumors, and increased hypermethylation of CpG islands within right tumors.

Conclusions

Differences in molecular mechanisms captured here highlight distinctions in tumorigenesis and progression between left and right colon tumors, which will serve as the basis for future studies, influencing the efficacies of existing and future diagnostic, prognostic and therapeutic interventions.

Analysis of clinicopathological features and prognosis of 1315 cases in colorectal cancer located at different anatomical subsites

PURPOSE

Compare and analyze the clinicopathological features and prognosis of 1315 patients with colorectal cancer located at different anatomical subsites.

METHODS

A retrospective study was conducted to analyze the clinicopathological features and prognosis from 1315 patients with colorectal cancer who underwent surgery in the department of gastrointestinal surgery at the Second Affiliated Hospital of Dalian Medical University from January 2013 to January 2019. Among them, 287 patients were divided into the right-sided colon cancer (RCC) group; 329 patients were included into the left-sided colon cancer (LCC) group and the remaining 699 patients were assigned to the rectal cancer (RC) group. Clinicopathological features such as gender, age, pathological differentiation, neurovascular invasion, TNM stage, related tumor markers, maximum tumor diameter (MTD), median survival time and overall survival rate were extracted and analyzed.

RESULTS

Patients in the RCC group had the oldest age of onset, highest positive rate of serum CA199 and greatest number of poorly differentiated adenocarcinomas among the three groups and significant statistical differences were found. The RC group had the highest positive rate of vascular invasion (42.9%) and the greatest number of patients in stage I and IV (19% and 3.9%, respectively). Besides, the number of patients with stage T1-T2 adenocarcinoma in RC group was also the highest among the three groups. There were no significant differences in gender, perineural invasion as well as serum levels of CEA, CA724 and CA242. The median survival time of RCC, LCC and RC were 72, 70 and 73 months, respectively, with significant inter-group differences (P = 0.049).

CONCLUSION

The age of onset of right-sided colon cancer is the oldest on average and poorly differentiated tumors accounted for the highest proportion. Besides, average maximum tumor diameter is the largest in right-sided colon cancer. In terms of median survival time, LCC is worse than RCC and RC. Colorectal cancer at different anatomical subsites has different epidemiological, clinicopathological features and prognosis. Fully understanding the clinicopathological features of colorectal cancer at different anatomical subsites is of certain guiding significance for the clinical diagnosis and treatment of colorectal cancer, and is conducive to individualized treatment and accurate treatment.

Sex- and site-specific differences in colorectal cancer risk among people with type 2 diabetes

PURPOSE

The prevalence of colorectal cancer is higher among patients with type 2 diabetes mellitus (T2D) than among patients without diabetes. Furthermore, men are at higher risk for developing colorectal cancer than women in the general population and also subsite-specific risks differ per sex. The aim was to evaluate the impact of T2D on these associations.

METHODS

A population-based matched cohort study was performed using data from the PHARMO Database Network. Patients with T2D were selected and matched (1:4) to diabetes free controls. Cox proportional hazards models were used to estimate hazard ratios (HRs) for CRC and its subsites. HRs were determined per sex and adjusted for age and socioeconomic status. The ratio of distal versus proximal colon cancer was calculated for people with T2D and controls per sex and stratified by age.

RESULTS

Over 55,000 people with T2D were matched to > 215,000 diabetes free controls. Men and women with T2D were 1.3 times more likely to develop colorectal cancer compared to controls. Men with T2D were at higher risk to develop distal colon cancer (hazard ratio (95% confidence interval), 1.42 (1.08-1.88)), and women with T2D were at higher risk for developing proximal colon cancer (hazard ratio (95% confidence interval), 1.58 (1.13-2.19)). For rectal cancer, no statistically significant risk was observed for both men and women.

CONCLUSIONS

Sex-specific screening strategies and prevention protocols should be considered for people with T2D. More tailored screening strategies may optimize the effectiveness of colorectal cancer screening in terms of reducing incidence and mortality.

Comparative proteogenomic analysis of right-sided colon cancer, left-sided colon cancer and rectal cancer reveals distinct mutational profiles

Right-sided colon cancer (RCC) has worse prognosis compared to left-sided colon cancer (LCC) and rectal cancer. The reason for this difference in outcomes is not well understood. We performed comparative somatic and proteomic analyses of RCC, LCC and rectal cancers to understand the unique molecular features of each tumor sub-types. Utilizing a novel in silico clonal evolution algorithm, we identified common tumor-initiating events involving APC, KRAS and TP53 genes in RCC, LCC and rectal cancers. However, the individual role-played by each event, their order in tumor development and selection of downstream somatic alterations were distinct in all three anatomical locations. Some similarities were noted between LCC and rectal cancer. Hotspot mutation analysis identified a nonsense mutation, APC R1450* specific to RCC. In addition, we discovered new significantly mutated genes at each tumor location, Further in silico proteomic analysis, developed by our group, found distinct central or hub proteins with unique interactomes among each location. Our study revealed significant differences between RCC, LCC and rectal cancers not only at somatic but also at proteomic level that may have therapeutic relevance in these highly complex and heterogeneous tumors.

Clinicopathological differences and survival outcomes with first-line therapy in patients with left-sided colon cancer and rectal cancer: Pooled analysis of 2879 patients from AGITG (MAX), COIN, FOCUS2, OPUS, CRYSTAL and COIN-B trials in the ARCAD database

PURPOSE

Patients with left-sided colon tumours have better survival and respond differently to biologics compared with patients with right-sided tumours. Left-sided colon tumours and rectal cancers are often grouped together. Herein, we examined the clinicopathological differences and outcomes between left-sided colon and rectal cancers.

PATIENTS AND METHODS

Data from 2879 metastatic colorectal cancer patients enrolled on six first-line clinical trials during 2004-2010 were pooled. Patients were included if the primary tumour origin was clearly defined. Progression-free survival (PFS) and overall survival (OS) were compared in the two groups after adjusting for patient and tumour characteristics, metastatic sites and the first-line regimen.

RESULTS

In total, 1374 patients with metastatic left-sided colon cancer and 1505 patients with metastatic rectal cancers were evaluated. Left-sided colon cancer patients were more likely to be female (40.1% versus 32.6%; P < 0.0001) and older (31.0% ≥ 70 years versus 25.8%; P = 0.0033) compared with rectal cancers patients. Patients with left-sided colon cancer had higher rates of liver metastases (80.9% versus 72.3%, P < 0.0001) but lower rates of lung metastases (34.2% versus 53.8%, P < 0.0001). KRAS mutations were slightly less frequent among left-sided tumours (34.8% versus 40.5%; P = 0.0103). Patients with left-sided tumours had approximately similar PFS (median 7.4 versus 6.9 months; hazard ratio [HR] 0.92, 95% confidence interval [CI] 0.87-1.03; P = 0.1998) and OS (median 17.4 versus 16.6 months; HR 0.99, 95% CI 0.91-1.07; P = 0.7597) compared with rectal cancer patients.

CONCLUSION

The site of tumour origin within the left side was not prognostic of outcomes. Moreover, neither bevacizumab nor cetuximab impacted, differently, the findings of the comparisons in outcomes between patients with left-sided colon tumours or rectal cancers.

Plasma metabolomic profiling distinguishes right-sided from left-sided colon cancer

BACKGROUND

Many studies have demonstrated that right-sided colon cancer (RCC) has a higher mortality rate and worse prognosis than left-sided colon cancer (LCC). However, the underlying biological mechanism that can account for these differences is unclear.

METHODS

In this study, plasma metabolic profiles in 147 LCC patients and 105 RCC patients were systematically analyzed by the ultra high performance liquid chromatography quadruple time-of-flight mass spectrometry (UHPLC-QTOF/MS) platform in conjunction with univariate and multivariate statistical analysis.

RESULTS

Metabolic signatures revealed considerable differences between patients with RCC and LCC, and clear separations were observed between the two groups in partial least-squares discriminant analysis score plots. In total, six metabolites were identified as potential metabolite markers for tumor location in RCC compared with LCC, including upregulated trimethylamine N-oxide and indoxyl sulfate, and downregulated anserine, L-targinine, gamma-glutamyl-gamma-aminobutyraldehyde and pyridoxal 5'-phosphate. These differences highlight that significant alternations occur in the pathways of methane metabolism, arginine and proline metabolism, histidine metabolism, beta-alanine metabolism and vitamin B6 metabolism in RCC compared with LCC.

CONCLUSIONS

Identified biomarkers and metabolic pathways may facilate our understanding of the different mortality rates and prognoses between RCC and LCC.

Primary Tumor Location in Colorectal Cancer: Comparison of Right- and Left-Sided Colorectal Cancer Characteristics for the Interventional Radiologist

One area which has emerged as an important factor for predicting molecular profile and treatment outcomes in metastatic colorectal cancer (mCRC) is primary tumor location. The importance of molecular characteristics of colorectal cancer has been firmly established in terms of prognosis and treatment algorithms for many years. Recent studies have also suggested that molecular profiles are important in locoregional therapies as well, with some data suggesting changes in treatment algorithms based on tumor location. Therefore, it is important for interventional radiologists to understand the basic molecular characteristics and development pathways of mCRC. Here, these disease characteristics are reviewed and the differences in left- versus right-sided primary tumor location are explored.

Comparison of survival between right-sided and left-sided colon cancer in different situations

Mountain of studies has showed that right‐sided colon cancer (RSCC) and left‐sided colon cancer (LSCC) have different clinical presentation and biologic features and should be considered as two distinct disease entities. The survival difference between RSCC and LSCC remains controversial. Using Surveillance, Epidemiology, and End Results (SEER) database, we identified colon adenocarcinoma patients from 2004 to 2013. The 5‐year cause‐specific survival (CSS) was our primary endpoint. All statistical analyses were performed using the Intercooled Stata 13.0. All statistical tests were two‐sided. The study included 95,847 (58.72%) RSCC and 67,385 (41.28%) LSCC patients. RSCC patients were older, more often females, more Caucasian, more unmarried, more advanced T and N stage, larger tumor sizes, and more poorly differentiated tumor, while LSCC patients had more stage IV diseases. Location was an independent prognostic factor in the multivariable analysis. Compared with RSCC patients, the hazard ratio for LSCC was 0.87, 95% CI: 0.85–0.89 P < 0.001. There was no survival difference between RSCC and LSCC in the following situations: older than 68 years old, T3–4, N0, poorly differentiated, and undifferentiated diseases. We firstly reported that RSCC patients had a better prognosis than LSCC in mucinous adenocarcinoma/signet ring cell carcinoma patients. RSCC patients also had a better prognosis than LSCC in stage II disease. There is a need for further subdivisions when analyzing the survival difference between RSCC and LSCC patients. RSCC had lower mortality rate than LSCC in stage II disease and mucinous adenocarcinoma/signet ring cell carcinoma patients.

Clinical significance of circulating immune cells in left- and right-sided colon cancer

Background

Left-sided and right-sided colon cancers (LCCs and RCCs, respectively) differ in their epidemiology, pathogenesis, genetic and epigenetic alterations, molecular pathways and prognosis. Notably, immune response gene expression profiles have been shown to differ between patients with LCC and patients with RCC. The immune system plays an important role in tumor immunosurveillance, and there is increasing evidence that peripheral blood immune cells have a profound influence on tumor prognosis. This study aimed to determine the clinical significance of circulating immune cells with respect to colon tumor locations.

Methods

Different types of circulating immune cells were separated and analysed based on their surface markers by flow cytometry. We compared the numbers of dendritic cells (DCs) and T cell subsets in the peripheral blood of 94 patients with RCC or LCC and analysed the proportions of these immune cells in relation to tumor stage, tumor differentiation and lymphatic metastasis.

Results

We show that at later tumor stages, patients with LCC had higher levels of circulating myeloid DCs (P = 0.049) and plasmacytoid DCs (P = 0.018) than patients with RCC. In poorly differentiated tumors, LCC patients had significantly higher amount of plasmacytoid DCs (P = 0.036), CD4⁺ memory T (Tm) cells (P = 0.012), CD4⁺ T cells (P = 0.028), Tm cells (P = 0.014), and regulatory T cells (P = 0.001) than RCC patients. The levels of circulating CD4⁺ T cells, Tm cells and CD4⁺ Tm cells were significantly elevated at later stages in patients with LCC or RCC, while these cells decreased in poorly differentiated tumors in patients with RCC. Moreover, CD4⁺ Tm cell and CD4⁺ T cell levels are significantly associated with lymph node metastasis in patients with LCC and RCC.

Discussion

Circulating immune cells were associated with tumor location, tumor stage and tumor differentiation, and can be used to predict lymphatic metastasis in patients with colon cancer. This variation in systemic immunity could contribute to the differential prognosis of patients with colon cancer.

Differences in prognosis and molecular biological features between left- and right-sided colon cancer

Apart from differences in epidemiologic, pathologic and symptomatic features, the natural prognosis, therapeutic prognosis, as well as survival after relapse also show great differences between left- and right-sided colon cancer. Those differences in prognosis are noticed to be dependent on tumor stage and also thought to be due to the variant genetic background and molecular biological features. In this review, we summarize the differences in prognosis and molecular biological features between left- and right-sided colon cancer, and discuss the possible connections between clinical and molecular differences. Taking into account the impact that location and differentially expressed molecules may have on prognosis, clinicians could have a more accurate estimate on the prognosis of colon cancer patients.

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

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

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

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

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