Difference in the recurrence rate between right- and left-sided colon cancer: a 17-year experience at a single institution. Surg Today. 2014;44:1685-1691. [PMID: 24126535 PMCID: PMC4138436 DOI: 10.1007/s00595-013-0748-5]

Robot-assisted vs. laparoscopic right hemicolectomy in octogenarians and nonagenarians: an analysis of the US nationwide inpatient sample 2005-2018

BACKGROUND

Colorectal cancer (CRC) is a significant health concern, particularly among older adults. Outcomes between laparoscopic and robot-assisted surgeries for right-sided colon cancers in the oldest old population have yet to be evaluated despite increased use of these surgeries.

AIM

This study aimed to compare clinical outcomes after robot-assisted right hemicolectomy (RARH) versus laparoscopic right hemicolectomy (LRH) in octogenarian and nonagenarian patients.

METHODS

This population-based, retrospective and observational study analyzed the data of adults ≥ 80 years old diagnosed with right-side colon cancer who received RARH or LRH. All data were extracted from the US National Inpatient Sample (NIS) database 2005-2018. Associations between type of surgery and in-hospital outcomes were determined using univariate and multivariable logistic regression and linear regression analysis.

RESULTS

Data of 7,550 patients (representing 37,126 hospitalized patients in the U.S.) were analyzed. Mean age of the study population was 84.8 years, 61.4% were females, and 79.1% were non-smokers. After adjusting for relevant confounders, regression analysis showed that patients undergoing RARH had a significantly shorter LOS (adjusted Beta (aBeta), -0.24, 95% CI: -0.32, -0.15) but greater total hospital costs (aBeta, 26.54, 95% CI: 24.64, 28.44) than patients undergoing LRH. No significant differences in mortality, perioperative complications, and risk of unfavorable discharge were observed between the two procedures (p > 0.05). Stratified analyses by frailty status revealed consistent results.

CONCLUSIONS

RARH is associated with a significantly shorter LOS but higher total hospital costs than LRH among octogenarians and nonagenarians. Other short-term outcomes for this population are similar between the two procedures, including in-hospital mortality, perioperative complications, and unfavorable discharge. These findings also apply to frail patients.

Expression and Prognosis of Differential Gene Troponin T1 Between Right and Left Colon Cancers

Colorectal cancer (CRC) is one of the most common digestive tract tumors in humans. At present, many scholars believe that the primary site of the tumor has a direct and profound impact on its curative effect. There are significant differences in the expression of many genes, tumor microenvironment, and prognosis between the left and right colon. However, there is a lack of detailed studies on whether the differentially expressed genes in the left and right colon significantly impact the prognosis of patients with CRC. Troponin T1 ( TNNT1 ) is an important gene that affects the prognosis difference between left and right colon cancer screening from "The Cancer Genome Atlas" database. By analyzing the differential gene expression data and clinical data of the left and right hemicolons in the database, the online prognostic database was used to screen the key molecules that significantly affect the tumor immune microenvironment and patient prognosis and to predict their functions and pathways. Quantitative reverse transcription-polymerase chain reaction was used to verify the expression difference of TNNT1 in CRC cell lines SW480 and HCT116, and normal human colorectal epithelial cell line FHC. The relationship between TNNT1 expression in 88 pairs of CRC samples and clinical information and pathologic parameters of patients with CRC was analyzed to judge the impact of TNNT1 expression on patient survival. Database analysis showed that TNNT1 was significantly overexpressed in CRC, and TNNT1 was one of the main differential genes between left colon cancer (LCC) and right colon cancer (RCC). The expression of TNNT1 was significantly increased in RCC, which could lead to poor prognosis of patients. Quantitative reverse transcription-polymerase chain reaction indicated that the expression of TNNT1 was significantly up-regulated in CRC cell lines SW480 and HCT116. Eighty-eight immunohistochemistry (IHC) of CRC tissues and adjacent tissues suggested that the expression of TNNT1 in CRC was significantly higher than that in normal adjacent tissues. By analyzing the clinical information and pathologic indicators matched with these clinical samples, we found that high TNNT1 expression in the primary tumor location (right colon) and high N stage (N2, N3) were unfavorable factors affecting the prognosis of patients with CRC. Multivariate Cox regression analysis suggested that high expression of TNNT1 may be an independent risk factor for the prognosis of patients with CRC. As one of the main differential genes between LCC and RCC, TNNT1 is representative to some extent. Its high expression may be one of the reasons why the prognosis of patients with RCC is worse than that of patients with LCC.

Prognostic impact of primary tumour location after curative resection in Stage I-III colorectal cancer: a single-centre retrospective study

OBJECTIVE

The relationship of tumour site with post-recurrence course and outcome after primary surgery in resectable colorectal cancer is unclear. This study investigated the prognostic impact of primary tumour location following radical resection without preoperative treatment in Stage I-III colorectal cancer.

METHODS

We analyzed 3770 patients with Stage I-III colorectal cancer who underwent curative resection at our hospital during 2000-15. We defined the right-sided colon as the cecum, ascending colon and transverse colon, and the left-sided colon as the descending colon, sigmoid and rectosigmoid junction. Patients were divided into three groups according to tumour site: right-sided colon, left-sided colon and rectum. Endpoints were overall survival, recurrence-free survival by stage and survival after recurrence, respectively.

RESULTS

The 5-year overall survival rates of patients with stage I left-sided colon cancer, right-sided colon cancer and rectal cancer were 98.2, 97.3 and 97.2%, respectively (P = 0.488). The 5-year overall survival rates of patients with Stage II left-sided colon cancer, right-sided colon cancer and rectal cancer were 96.2, 88.7 and 83.0, respectively (P = 0.070). The 5-year overall survival rates of patients with Stage III left-sided colon cancer, right-sided colon cancer and rectal cancer were 88.7, 83.0 and 80.2, respectively (P = 0.001). The 5-year recurrence-free survival rates of patients with Stage I left-sided colon cancer, right-sided colon cancer and rectal cancer were 95.1, 94.5 and 90.6% (P = 0.027). The 5-year recurrence-free survival rates of patients with Stage II left-sided colon cancer, right-sided colon cancer and rectal cancer were 85.2, 90.2 and 76.1%, respectively (P < 0.001). The 5-year recurrence-free survival rates of patients with Stage III left-sided colon cancer, right-sided colon cancer and rectal cancer were 75.3, 75.3 and 59.8%, respectively (P < 0.001). Right-sided colon cancer was significantly associated with better recurrence-free survival compared with left-sided colon cancer (HR 1.29, 95% CI 1.03-1.63; P = 0.025) and rectal cancer (HR 1.89, 95% CI 1.51-2.38; P < 0.001) after adjusting for clinical factors. Amongst patients with recurrence, right-sided colon cancer was significantly associated with poorer survival after recurrence compared with left-sided colon cancer (HR 0.68, 95% CI 0.48-0.97; P = 0.036), and showed a tendency towards poorer survival after recurrence compared with rectal cancer (HR 0.79, 95% CI 0.57-1.10; P = 0.164).

CONCLUSIONS

In Stage I-III colorectal cancer without preoperative treatment, our results suggest that the three tumour sites (right-sided colon, left-sided colon or rectum) may have prognostic significance for recurrence-free survival and survival after recurrence, rather than sidedness alone.

Update on Targeted Therapy and Immunotherapy for Metastatic Colorectal Cancer

Metastatic colorectal cancer remains a deadly malignancy and is the third leading cause of cancer-related death. The mainstay of treatment for metastatic colorectal cancer is chemotherapy, but unfortunately, even with recent progress, overall survival is still poor. Colorectal cancer is a heterogeneous disease, and the underlying genetic differences among tumors can define the behavior and prognosis of the disease. Given the limitations of cytotoxic chemotherapy, research has focused on developing targeted therapy based on molecular subtyping. Since the early 2000s, multiple targeted therapies have demonstrated efficacy in treating metastatic colorectal cancer and have received FDA approval. The epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), and DNA mismatch repair pathways have demonstrated promising results for targeted therapies. As new gene mutations and proteins involved in the oncogenesis of metastatic colorectal cancer are identified, new targets will continue to emerge. We herein provide a summary of the updated literature regarding targeted therapies for patients with mCRC.

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.

Serum Cytokine and miRNA Levels Are Differently Expressed in Right- and Left-Sided Colon Cancer

The tumor location in colorectal cancer (right- or left-sided colon cancer) is a key factor in determining disease progression. Right- and left-sided colon tumors are different in their clinical and molecular characteristics. Dysregulation of serum levels of proinflammatory cytokines, such as Transforming Growth Factor β (TGF-β) and Tumor Necrosis Factor-α (TNF-α), and Peroxisome Proliferator Activated Receptor-γ (PPAR-γ), known to be a growth-limiting and differentiation-promoting factor, as well as changes in miRNAs expression, are the major signaling pathways involved in the pathogenesis of this neoplasia. In the serum from 60 colorectal cancer (CRC) patients, we compared the differences in the expression of the levels of TGF-β, TNF-α, and PPAR-γ and in the expression of the main human miRNAs between right and left CRC. A significant over-expression in the TGF-β and TNF-α levels was observed in the serum from right-sided colon cancer patients. For the PPAR-γ, the patients with CRC located on the right-side showed lower levels than those detected in the serum from left-sided CRC subjects. Furthermore, significant differences also existed in the expression of specific circulating miRNAs between right- and left-sided CRC. In particular, the right upregulated miRNAs were all involved in the cell growth and proliferation related pathways. These findings confirm that the analysis of circulating levels of TGF-β, TNF-α, and PPAR-γ, as well as the study of the specific miRNAs in the serum, are able to identify specific characteristics of CRC patients, useful for choosing a personalized treatment protocol.

Left-Sided Colon Cancer and Right-Sided Colon Cancer: Are They the Same Cancer or Two Different Entities?

Background Colon cancer is one of the most common cancers in the world and one of the main causes of cancer-related deaths. In Morocco, it occupies the first place among digestive cancers. Right-sided and left-sided colon cancers have different embryological, epidemiological, pathological, genetic, and clinical characteristics. This distinction leads to differences in the evolution and prognosis of the disease. This study aimed to identify epidemiological factors and clinical and pathological characteristics that can influence perioperative and prognostic outcomes in patients with right-sided colon cancer compared to those with left-sided colon cancer. Methodology We conducted a retrospective cohort study over a period of nine years from January 2012 until December 2020. We included 277 patients divided into two groups, namely, right colon cancer (group 1) (n = 99) and left colon cancer (group 2) (n = 178). Results The average age of our series was 57.4 years, with extremes ranging from 19 to 89 years old (SD = ±13.6451 years). The average age in the right colon group was 55.97 (SD = ±13.341 years). The average age in the left colon group was 58.18 (SD = ±13.69 years). The male gender had a predominance, with a sex ratio of 1.3 for both groups. Among the patients in group 2, 65% showed lymph node involvement on the CT scan, whereas only 34% of patients in group 1 displayed the same condition. The recurrence rate in the right-sided colon cancer group was 22.2% compared to 24.9% in the left-sided group. The five-year overall survival was estimated for the right-sided and left-sided colon cancer groups at 87% and 96.5%, respectively. In patients with stage III and IV cancer, overall survival was better for those who underwent surgery for left-sided colon cancer compared to those who underwent surgery for right-sided colon cancer (p = 0.029). In the case of vascular emboli or involvement of the perineural sheath, there was no significant difference in overall survival (p = 0.446 and p = 0.655, respectively). The three-month survival without recurrence was almost identical in both groups (31% for right-sided colon cancers and 30.9% for left-sided colon cancers). Age over 61 years was a predictive factor of poor prognosis in recurrence-free survival (hazard ratio = 3.245; p = 0.023). Conclusions We identified factors that can influence perioperative outcomes and prognosis in patients with right-sided colon cancer compared to those with left-sided colon cancer. Our findings suggest that age and lymph node involvement along with other factors play a role in the overall survival and recurrence outcomes of these patients. Further research is necessary to explore these differences and develop personalized treatment plans for patients with colon cancer.

Is serum thymidine kinase 1 a prognostic biomarker in primary tumor location of colorectal carcinomas?

AIM

To assess whether serum thymidine kinase 1 (STK1p), CEA and CA19.9 can be used as prognostic biomarkers in the primary tumor location (PTL) of colorectal carcinoma (CRC). Additional clinical factors of TNM stage, pathological grade, age and sex were also included.

METHODS

STK1p was determined by an ECL-dot-blot assay, and CEA/CA19.9 was determined by an automatic electrochemiluminescence analyzer in a retrospective presurgery of right-colon carcinoma (R-CC, n = 90), left-colon carcinoma (L-CC, n = 128) and rectal carcinoma (RC, n = 270). Prognostic factors were evaluated by COX and overall survival (OS).

RESULTS

The multivariate-COX and OS in relation to the prognostic factors of PTL in CRC were different and complex. An elevated STK1p value was significantly associated with poor OS in RC (P = 0.002) and L-CC (P = 0.037) but not in R-CC (P > 0.05). Elevated CEA (P≈.000) and CA19.9 (P≈.000) were significantly associated with poor OS in RC but not in L-CC and R-CC. Multivariate-COX showed that STK1p (P = 0.02, HR = 1.779, 95%CI 1.30-7.582), CEA (P = 0.001, HR = 2.052, 95%CI 1.320-3.189), CA19.9 (P≈.000, HR = 2.574, 95%CI 1.592-4.162) and TNM-stage (P≈.000, HR = 2.368, 95%CI 1.518-3.694) were independent prognostic factors in RC, while TNM-stage was an independent prognostic factor only in R-CC (P = 0.011, HR = 3.139, 95% CI 1.30-7.582) and L-CC (P≈.000, HR = 4.168, 95%CI 1.980-8.852). Moreover, elevated STK1p was significantly more sensitive (P < .001) for predicting mortality than CEA and CA19.9. No correlation was found between STK1p, CEA or AFP.

CONCLUSION

Combining TNM stage and suitable biomarkers, STK1p provides further reliable information on the survival of PTL of CRC.

Poorer Survival in Patients with Cecum Cancer Compared with Sigmoid Colon Cancer

Background and Objectives: An increasing number of studies have shown the influence of primary tumor location of colon cancer on prognosis, but the prognostic difference between colon cancers at different locations remains controversial. After comparing the prognostic differences between left-sided and right-sided colon cancer, the study subdivided left-sided and right-sided colon cancer into three parts, respectively, and explored which parts had the most significant prognostic differences, with the aim to further analyze the prognostic significance of primary locations of colon cancer. Materials and Methods: Clinicopathological data of patients with colon cancer who underwent radical surgery from the Surveillance, Epidemiology, and End Results Program database were analyzed. The data was divided into two groups (2004−2009 and 2010−2015) based on time intervals. Two tumor locations with the most significant survival difference were explored by using Cox regression analyses. The prognostic difference of the two locations was further verified in survival analyses after propensity score matching. Results: Patients with right-sided colon cancer had worse cancer-specific and overall survival compared to left-sided colon cancer. Survival difference between cecum cancer and sigmoid colon cancer was found to be the most significant among six tumor locations in both 2004−2009 and 2010−2015 time periods. After propensity score matching, multivariate analyses showed that cecum cancer was an independent unfavorable factor for cancer specific survival (HR [95% CI]: 1.11 [1.04−1.17], p = 0.001 for 2004−2009; HR [95% CI]: 1.23 [1.13−1.33], p < 0.001 for 2010−2015) and overall survival (HR [95% CI]: 1.09 [1.04−1.14], p < 0.001 for 2004−2009; HR [95% CI]: 1.09 [1.04−1.14], p < 0.001 for 2010−2015) compared to sigmoid colon cancer. Conclusions: The study indicates the prognosis of cecum cancer is worse than that of sigmoid colon. The current dichotomy model (right-sided vs. left-sided colon) may be inappropriate for the study of colon cancer.

Anatomical Distribution of Colon Cancer: A Retrospective 10-year Study to Evaluate Rightward Shift in Two Referral Hospitals in Iran

Background: In Iran, the incidence of colorectal cancer has been increasing over the last 25 years. Although left-sided colon cancers are still more common, several studies in recent years have shown a shift toward right colon. This rightward shift could have important clinical and healthcare consequences, as right-sided tumors generally have poorer prognoses compared to left-sided tumors and besides, are more likely to be missed in screening colonoscopy. Objectives: This retrospective study aimed at describing the demographic and clinicopathologic characteristics of patients with colon cancer based on tumor sidedness in two referral hospitals in Tehran. Methods: Data of the patients with colon cancer who had been treated from 2010 to 2020 in two referral hospitals in Tehran, Iran were retrospectively reviewed. Collected data included patients’ demographics, tumor histology and differentiation, tumor location, stage, and disease-free survival (DFS). Results: A total of 1535 cases entered the study including 849 (55.3%) males and 686 (44.7%) females with a mean age of 58.22 years (range: 22 - 89). Regarding the sidedness, 800 (52.1%) had left-sided and 735 (47.9%) had right-sided tumors. Although there were more cases of left-sided tumors compared to right-sided ones on total, there existed a trend toward shifting to the right side, which was statistically significant. There existed more cases of poorly differentiated tumors in the right side and besides, right-sided tumors had poorer DFS compared to the left-sided tumors (68.3% vs 78.3%). Conclusions: Left and right colon tumors differ in molecular mechanisms involved in tumorigenesis. These differences in epidemiological, molecular and histological parameters can have clinical implications. Tumor-sidedness should be acknowledged as an important epidemiological parameter with significant impacts on screening, tumorgenesis, response to treatment, and prognosis.

Comparison of Resected Malignant Tumors of the Right- and Left-Sided Colon—Is There a Difference?

Embryological, anatomical, and immunological differences between the right-sided and left-sided colons are well known, but the difference in oncological behavior of colon tumors has only recently become the main subject of studies. Published articles propose that there is a difference not only in symptoms, but also in survival. Our aim was to analyze the clinicopathological and oncological differences among our patients who had been operated for colon cancer in our department. We examined the historical data of our patients who underwent colon resection for malignancy between 1st of January 2016 and 31st of December 2018. Tumor markers, histological results, postoperative complications, and oncological therapies were investigated. The primary outcome was overall survival. We analyzed our patients’ survival data with Kaplan–Meier log-rank test and Cox regression analysis. In our study, 267 patients were enrolled. One hundred thirty-three (49.8%) patients had right-sided colon cancer; 134 (50.2%) patients had left-sided colon cancer. Patients with right-sided colon cancer were significantly more likely to have mucinous adenocarcinoma (p = 0.037). No significant differences were revealed in overall survival between right-sided colon cancer and left-sided colon cancer patients (p = 0.381). Additional subgroup analysis showed that there were no significant differences in overall survival for laterality neither in the metastatic group (p = 0.824) nor in the non-metastatic group (p = 0.345). Based on the conflicting previous study results, our findings repeatedly highlight that the relationship between tumor location in the colon and overall survival is not straightforward.

Dynamic Co-Evolution of Cancer Cells and Cancer-Associated Fibroblasts: Role in Right- and Left-Sided Colon Cancer Progression and Its Clinical Relevance

Simple Summary

The versatile crosstalk between cancer cells and cancer-associated fibroblasts (CAFs) of the tumour microenvironment (TME) drives colorectal carcinogenesis and heterogeneity. Colorectal cancer (CRC) can be classified by the anatomical sites from which the cancer arises, either from the right or left colon. Although the cancer cell–CAF interaction is being widely studied, its role in the progression of cancer in the right and left colon and cancer heterogeneity are still yet to be elucidated. Further insight into the complex interaction between different cellular components in the cancer niche, their evolutionary process and their influence on cancer progression would propel the discovery of effective targeted CRC therapy.

Abstract

Cancer is a result of a dynamic evolutionary process. It is composed of cancer cells and the tumour microenvironment (TME). One of the major cellular constituents of TME, cancer-associated fibroblasts (CAFs) are known to interact with cancer cells and promote colorectal carcinogenesis. The accumulation of these activated fibroblasts is linked to poor diagnosis in colorectal cancer (CRC) patients and recurrence of the disease. However, the interplay between cancer cells and CAFs is yet to be described, especially in relation to the sidedness of colorectal carcinogenesis. CRC, which is the third most commonly diagnosed cancer globally, can be classified according to the anatomical region from which they originate: left-sided (LCRC) and right-sided CRC (RCR). Both cancers differ in many aspects, including in histology, evolution, and molecular signatures. Despite occurring at lower frequency, RCRC is often associated with worse diagnosis compared to LCRC. The differences in molecular profiles between RCRC and LCRC also influence the mode of treatment that can be used to specifically target these cancer entities. A better understanding of the cancer cell–CAF interplay and its association with RCRC and LRCR progression will provide better insight into potential translational aspects of targeted treatment for CRC.

Outcomes of right-sided and left-sided colon cancer after curative resection

The right and left side of the colon derived from the midgut and hindgut, respectively. Previous studies have reported different characteristics of right-sided colon cancer (RCC) and left-sided colon cancer (LCC), but oncological outcomes remain unclear. This study compared the outcomes of RCC and LCC. This retrospective study included 1017 patients who received curative colectomy for stage I-III colon cancer at a single institute between August 2008 and December 2019. Overall survival (OS) and time to recurrence (TTR) were analyzed as outcome measurements. No significant difference in the OS or TTR of patients with RCC and LCC were observed. In subgroup analysis, RCC was associated with shorter TTR than LCC in stage II colon cancer (HR 2.36, 95% confidence interval 1.24–4.48, p < 0.01). Multivariate analysis demonstrated that right sidedness, R1 resection, low body mass index (BMI) and adjuvant chemotherapy were independent factors for poor prognosis for stage II colon cancer. Low BMI, perineural invasion, higher T stage and N2 stage were independent factors for poor prognosis for stage III colon cancer. The results were confirmed by multivariate analysis after propensity score matching. Our study revealed that RCC was an independent risk factor for recurrence in stage II colon cancer.

Evaluating the value of tumor length times width in colorectal adenocarcinoma with different tumor locations

The T classification, which reflects the vertical growth pattern of the tumor, is one of the most important prognostic factors in colorectal cancer. We aimed to investigate the prognostic value of tumor length and width in patients with colorectal cancer (CRC). A total of 259 patients with stage I-III CRC who underwent curative resection were reevaluated according to tumor location. One-way ANOVA analysis was conducted to investigate the relationship between the tumor length times width (TLTW) and clinical parameters. Univariate and multivariate analyses were conducted to analyze the potential prognostic factors affecting overall survival (OS) of patients with stage I-III CRC. In the entire cohort, the TLTW was analyzed as a continuous variable. The results suggested that TLTW (P = .003) and tumor location (P = .04) could be independent prognostic factors for patients with CRC. In addition, TLTW had an intimate relationship with tumor location (P < 0.001) and differentiation (P = .003). The mean TLTW of the right colon was significantly larger than mean TLTW of the left colon and rectal cancers. However, the mean TLTW of the left colon cancer was similar to that of the rectal cancer TLTW (P > 0.05, not shown). Subgroup analysis of TLTW according to tumor location suggested that TLTW was an independent prognostic factor for patients with right colon cancer (RCC) (P = .007) rather than left colon cancer (LCC) (P = .49) or rectal cancer (P = .16). Kaplan-Meier (K-M) analysis based on tumor location suggested that the survival rate of RCC patients had a distinctly higher trend rate than LCC patients and RECC patients in the long-term rather than in the short-term. TLTW is closely associated with tumor location in CRC. In addition, TLTW may be an independent prognostic factor for patients with RCC.

Identification of high-risk stage I colon and rectal cancer patients: a retrospective analysis of a large Japanese cohort

PURPOSE

Data regarding risk factors for recurrence in stage I colorectal cancer patients are limited. The aim of this study was to clarify the existence of a high-recurrence-risk population among stage I colorectal cancer patients.

METHODS

This analysis included 7,539 stage I colorectal cancer patients treated between 1997 and 2012 at 24 leading hospitals in Japan. Risk factors for time to recurrence were evaluated using a Cox proportional hazards model, and a high-risk group for recurrence was identified. Prognostic outcomes of high-risk stage I colorectal cancer patients were compared with those of low-risk stage I and stage II patients.

RESULTS

Multivariable analyses identified left-sided location (hazard ratio [HR]: 1.65, 95% confidence interval [CI]: 1.09-2.58), T2 tumors (HR: 1.80, 95% CI: 1.21-2.66), and lymphatic invasion (HR: 1.55, 95% CI: 1.05-2.28) as risk factors for recurrence in stage I colon cancer, and patients with these three risk factors were classified as high risk. For stage I rectal cancer, patients with poor differentiation (HR: 2.86, 95% CI: 1.21-5.69), T2 tumors (HR: 1.53, 95% CI: 1.07-2.23), and venous invasion (HR: 1.51, 95% CI: 1.08-2.13) were identified as high risk. The Kaplan-Meier analysis of cumulative recurrence rate and recurrence-free survival revealed that the high-risk stage I colorectal cancer patients have poorer clinical outcomes than the low-risk patients.

CONCLUSION

Although stage I colorectal cancer patients generally have a favorable prognosis after curative surgery, poorer prognosis was observed in high-risk stage I colorectal cancer patients than in low-risk patients.

Associations of Complete Blood Count Parameters with Disease-Free Survival in Right- and Left-Sided Colorectal Cancer Patients

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. Some complete blood count (CBC) parameters are found to be associated with CRC prognosis. In this study, ninety-seven pretreated CRC patients were included, and the patients were divided into two groups: left-sided and right-sided, depending on the anatomical location of the tumor. Based on clinicopathologic features including tumor budding, disease stages, and tumor anatomical location, levels of CBC parameters were compared, and disease-free survivals (DFS) were determined. There were differences between patients with different tumor budding scores for only three parameters, including red cell distribution width (RDW), numbers of platelets, and mean platelet volume (MPV). Furthermore, numbers of WBCs, monocytes, and MPV in CRC patients with early disease stages were higher than those with advanced stages. However, levels of eosinophil in CRC patients with advanced stages were higher than those with early stages. Depending on the tumor anatomical location, we observed that numbers of red blood cells (RBCs), hemoglobin (Hgb), and hematocrit (Hct) in CRC patients with left-sided tumors were higher than those with right-sided tumors. We found that low levels of MPV were associated with shorter DFS. However, high levels of eosinophils were associated with shorter DFS in all CRC patients. When patients were divided based on the tumor anatomical location, higher levels of MPV, MCHC, and Hgb were associated with better DFS in the left-sided but not right-sided CRC patients. However, left-sided, but not right-sided, CRC patients with high levels of eosinophil and RDW had shorter DFS. Furthermore, right-sided, but not left-sided, CRC patients with high levels of platelets tended to have a shorter DFS. Our data show that MPV and eosinophils could serve as potential prognostic biomarkers in pre-treatment CRC patients, regardless of the tumor anatomical location. Additionally, lower levels of MPV, MCHC, and Hgb, and high levels of eosinophils and RDW could be negative predictive biomarkers in left-sided CRC patients.

Evaluation and Prediction Analysis of 3- and 5-Year Survival Rates of Patients with Cecal Adenocarcinoma Based on Period Analysis

Background

Cecal adenocarcinoma has a high degree of malignancy and poor prognosis, thereby bringing serious disease burden to patients. The long-term survival rate of patients with cecal adenocarcinoma deserves us to explore more deeply. In addition, appropriate methods that evaluate the survival outcome of cecal adenocarcinoma are few.

Methods

This study used the data provided by the Surveillance, Epidemiology, and End Results (SEER) database to evaluate and predict the survival rates of patients with cecal adenocarcinoma from 2002 to 2016 and from 2017 to 2021, respectively. The cohort of population taken are all older than 20 years old, which is from National Cancer Institute. The period analysis was used to check the data in the SEER database. Reliable results could be obtained using period analysis, which provided important information for prevention and treatment strategies.

Results

From 2002 to 2016, the relative survival rate of patients with cecal adenocarcinoma increased yearly. Compared with those in previous 15 years, the relative survival rate between 2017 and 2021 still increased but to a low extent. The relative survival rates of patients with cecal adenocarcinoma were remarkably different in terms of age, sex, race, differentiation grade, stages, and socioeconomic status. Even if there is a significant improvement, the survival rate of patients with distant-stage cancer is at a very low level.

Conclusion

Understanding the survival rate of patients with cecal adenocarcinoma in the past 15 years is helpful in predicting the future trend and providing basic data and scientific basis to evaluate the harm of cecal adenocarcinoma to patients’ health, prepare cancer prevention plans, and evaluate the effect of cancer prevention and treatment by exploring the differences in survival rate corresponding to different ages, sexes, races, differentiation grades, stages, and socioeconomic status.

Preoperative Lymphocyte-to-Monocyte Ratio in the Prognostication of Advanced Resectable Colon Cancer: a Retrospective Observational Study

Lymphocyte-to-monocyte ratio (LMR) has been reported as a biomarker for predicting the prognosis of colorectal cancer. However, the clinical usefulness of LMR requires detailed research, which can contribute to better therapeutic strategies. A cohort of 554 patients with resectable advanced colon cancer in our institution was analyzed retrospectively. An analysis of stages II and III resectable advanced colon cancer was performed. LMR was useful for predicting overall survival (OS) and relapse-free survival (RFS). The ROC curve revealed an LMR value of 2.77 as a cutoff for OS. A high LMR was an independent prognostic factor and was associated with a high hazard ratio (HR) in all cases for OS (HR = 0.530, 95% confidence interval (CI) = 0.334-0.842, p = 0.007). A high LMR was not an independent prognostic factor in stage II cases but was a predictor with the strongest association with prognosis in patients with stage III cases for OS (HR = 0.383, 95% CI = 0.160-0.915, p = 0.031). LMR is a strong predictor of prognosis in patients with stage III colon cancer and may be useful in postoperative treatment options.

Right and Left Colorectal Cancer: Differences in Post-Surgical-Care Outcomes and Survival in Elderly Patients

Simple Summary

The objective of this investigation is to analyze the differences between right and left colon cancer survival and test if these differences have transcendental importance for assistance to improve the survival and quality care of these patients. The results show that both entities are significantly different in terms of evolution, progression, complications and survival. Patients with right colon cancer have a worse prognosis, even in the early stages of the disease, due to more advanced N stages, a larger tumor size, more frequently poorly differentiated tumors and a greater positivity of lymphovascular invasion than left colon cancer. Improvement of the prognosis can be implemented mainly by reducing the specific mortality of colon cancer by achieving early detection and also stratified and personalized by location and age of onset, as well as surgical and oncological treatment of these patients.

Abstract

(1) There is evidence of the embryological, anatomical, histological, genetic and immunological differences between right colon cancer (RCC) and left colon cancer (LCC). This research has the general objective of studying the differences in outcome between RCC and LCC. (2) A longitudinal analytical study with prospective follow-up of the case–control type was conducted from 1 January 2010 to 31 December 2017 including 398 patients with 1:1 matching, depending on the location of the tumor. Inclusion criteria: programmed colectomies, 15 cm above the anal margin, adults and R0 surgery. (3) Precisely 6.8% of the exitus occurred in the first 6 months of the intervention. At 6 months, patients with LCC presented a mean survival of 7 months higher than RCC (p = 0.028). In the first stages, it can be observed that most of the exitus are for patients with RCC (stage I p = 0.021, stage II p = 0.014). In the last stages, the distribution of the deaths does not show differences between locations (stage III p = 0.683, stage IV p = 0.898). (4) The results show that RCC and LCC are significantly different in terms of evolution, progression, complications and survival. Patients with RCC have a worse prognosis, even in the early stages of the disease, due to more advanced N stages, larger tumor size, more frequently poorly differentiated tumors and a greater positivity of lymphovascular invasion than LCC.

Poorer prognosis for neuroendocrine carcinoma than signet ring cell cancer of the colon and rectum (CRC-NEC): a propensity score matching analysis of patients from the Surveillance, Epidemiology, and End Results (SEER) database

PURPOSE

Colorectal neuroendocrine carcinomas (CRC-NECs) are rare, comprising < 1% of colorectal cancers. This study aimed to assess the incidence, clinicopathologic characteristics, prognostic factors, and treatment outcomes of CRC-NEC.

METHODS

We analysed the Surveillance, Epidemiology, and End Results (SEER) database to identify patients from 20 to 74 years old diagnosed with CRC-NEC or common CRC (non-NEC) during 2004-2013. Log-rank testing was conducted to assess survival differences. A competing-risks regression model was used to adjust for covariate effects in the propensity score-matched (PSM) cohort, and adjusted hazard ratios (HRs) were calculated for the raw and PSM cohorts.

RESULTS

We identified 67,484 patients (344 CRC-NEC and 67,140 non-NEC). Lymph node metastasis (LNM) was more common in CRC-NEC (75.29%, n = 259) than in non-NEC (51.53%, n = 34,600) (P < 0.001); 56.40% (n = 194) of CRC-NECs were located on the right side, while 18.31% (n = 63) were located on the left side, with a statistically significant difference in distribution (P < 0.001) compared to that in non-NEC CRC. Multivariate analysis indicated that a left-side location was an independent adverse prognostic factor for CRC-NEC (P = 0.043). CRC-NEC had the poorest cancer-specific survival (median CSS, 9.0 months) among assessed cancers, even poorer than that of signet ring cell cancer (median CSS, 24.0 months). However, both radical operation (P = 0.007) and chemotherapy (P = 0.008) were beneficial for CSS.

CONCLUSION

NEC is a rare and extremely aggressive tumour with a poor prognosis. Right-side NEC has a better prognosis than left-side NEC. Early diagnosis, radical surgery, and chemotherapy are imperative for improving survival.

Epidemiology and survival of colon cancer among Egyptians: a retrospective study

Introduction Colorectal cancer is the 4th commonest cancer in the world. Studies had shown different tumor behavior depending on the site, pathology and stage. However the characters of Egyptian colon cancer patients are not well addressed.

Method Computerized registry of a tertiary cancer hospital in Egypt was searched for colon cancer cases. Demographic, pathologic and treatment data were collected and analyzed using SPSS program.

Results About 360 colon cancer patients attended our center in the last 12 years. Tumor characters showed great diverse from that of developed countries, with especially different prognosis and survival.

Conclusion Egyptians have unique tumor characters and behavior, and different compliance with treatment regimens. Multicenter prospective studies, as well as evolving Egyptian treatment guidelines are needed to address this.

Microbial Community Profiling Distinguishes Left-Sided and Right-Sided Colon Cancer

The difference between left- and right-sided colon cancer has become the focus of global attention, and researchers have found differences in the morbidity, molecular biological characteristics, and response to targeted drug therapy between left- and right-sided colon cancer. Therefore, the identification of more effective predictive indicators is critical for providing guidance to future clinical work. We collected samples from different colon sites and regions and analyzed the identities and distributions of differentially expressed species in the microbiota in the left and right sides of the colon to better explore the pathogenesis of colon cancer and provided a basis for individualized drug therapy. We collected samples from different regions in the body of 40 patients with colon cancer, including stool and tissues. The Subjects were classified into four groups, and this classification was mainly based on the colon cancer distribution. The microbiota composition of the left-sided and right-sided colon samples was assessed by specifically amplifying the V3-V4 region of the 16S rDNA gene from DNA extracts from the samples. These amplicons were examined by Illumina HiSeq 2500 sequencing. The microbial taxa in the left-sided colon samples are more abundant than those in the right-sided colon samples. The flora in the left-sided colon samples, such as Clostridium perfringens and Fusobacterium nucleatum, might be associated with VEGF expression and are more likely to promote colon cancer. The microbiota distribution in the right-sided colon samples is less invasive and harmful and particularly rich in Bifidobacterium dentium. In addition, Streptococcus, which is the target of EGFR, was found to be expressed in both the left- and right-sided colon samples but was found at a higher level in the left-sided colon samples. Additionally, the differential pathways involved in the left-sided colon samples mainly mediate DNA damage, methylation, and histone modifications, whereas those in the right-sided colon samples are dominated by DNA synthesis. The comparison of only the geographical differences revealed a significant difference in the distribution of the microbial population. The adherent microbiota composition and structural changes between the left- and right-sided colon samples might contribute to the development of colon cancer, lead to different morbidities, and further affect the prognosis of patients and their sensitivity to targeted drugs. Therefore, the identification of the differential flora in the colon could be used as an indicator for predicting the occurrence and development of colon cancer, which is also beneficial for future individualized drug therapy.

Neutrophil-to-lymphocyte ratio is a prognostic factor for colon cancer: a propensity score analysis

Background

A large number of patients suffer recurrence after curative resection, and mortality from colon cancer remains high. The role of systemic inflammatory response, as reflected by neutrophil-to-lymphocyte ratio (NLR), in cancer recurrence and death has been increasingly recognized. This study aimed to analyze long-term oncologic outcomes of Stage II-III colon cancer to examine the prognostic value of NLR using a propensity score analysis.

Methods

A total of 375 patients with colon cancer underwent radical surgery between 2000 and 2014 at Tokyo Medical University Hospital. Long-term oncologic outcomes of these patients were evaluated according to NLR values. A cut-off NLR of 3.0 was used based on receiver operating characteristic curve analysis. Primary outcomes were overall survival (OS) and relapse-free survival (RFS). An analysis of outcomes according to tumor sidedness was also performed.

Results

Patients with lower NLR values (“lower NLR group”) were more likely to have lymph node metastasis compared to those with higher NLR values (“higher NLR group”) before case matching. After case matching, clinical outcomes were similar between the two groups. There were no significant differences in 5-year OS and 5-year RFS rates between the two groups before case matching based on propensity scores. After case matching, 5-year OS rates were 94.5% in the lower NLR group (n = 135) and 87.0% in the higher NLR group (n = 135), showing a significant difference (p = 0.042). Five-year RFS rates were 87.8% in the lower NLR group and 77.9% in the higher NLR group, also showing a significant difference (p = 0.032). Among patients with left-sided colon cancer in the matched cohort, 5-year OS and 5-year RFS rates were 95.2 and 87.3% in the lower NLR group (n = 88), respectively, and 86.4 and 79.2% in the higher NLR group (n = 71), respectively, showing significant differences (p = 0.014 and p = 0.047, respectively).

Conclusions

The NLR is an important prognostic factor for advanced colon cancer, especially for left-sided colon cancer.

Long-Term Outcomes of Laparoscopic Versus Open Surgery for Colon Cancer in Noncancer-Specific Hospital: Propensity Score Analysis

Background: Noninferiority of the laparoscopic approach compared with open surgery for colon cancer treatment has remained controversial. In this study, we aimed to evaluate the long-term outcomes of laparoscopic surgery (LS) versus open surgery (OPS). Methods: A total of 418 patients with Stage I-III colon cancer, who received radical surgery at the Tokyo Medical University Hospital from 2000 to 2014 were included. Propensity score analysis with overall survival (OS) and relapse-free survival (RFS) as the primary endpoints was performed retrospectively to reduce the effects of confounding factors between groups, including age, sex, body mass index, tumor size, clinical T stage, and clinical N stage. Results: After case matching, the 5-year OS rate was 87.8% in the OPS group (n = 97) and 90.1% in the LS group (n = 97; P = .59), indicating no significant difference. The 5-year RFS rate was 79.0% in the OPS group (n = 97) and 84.1% in the LS group (n = 97; P = .29), indicating no significant difference. Five-year cumulative local recurrence (LR) rates were 7.6% and 0% in the OPS group and the LS group, respectively, indicating a significant difference (P = .007). Five-year cumulative distant metastasis rates were 9.2% and 12.7% in the OPS group and the LS group, respectively (P = .49). Conclusion: Laparoscopic surgery appears to be a reasonable option with similar long-term outcomes and to have low LR rate to open surgery in colon cancer patients.

The prognostic relevance of primary tumor sidedness to surgical treatment for recurrent colon cancer

PURPOSE

The aim of this study was to investigate the predictive relevance of tumor sidedness on surgical resection after recurrence by evaluating the treatment outcomes after primary resection and recurrence in patients with localized colon cancer (CC).

METHODS

A total of 735 consecutive patients who underwent curative resection for Stage I-III CC from 1997 to 2013 were categorized as having either right- or left-sided CC, and survival after primary surgery and after recurrence were analyzed.

RESULTS

A total of 104 patients (14.1%) developed recurrence, 94 of which were in a single organ, and 59 patients underwent curative resection. For recurrence from both sides of the colon, a significantly better 5-year overall survival (OS) was experienced by patients who underwent curative resection compared to those who received palliative treatment (right: 42.2% vs not reached, respectively; P < 0.001; left: 71 vs 15.9%, respectively; P < 0.001). Meanwhile, a still worse OS was observed in patients with curative resection for recurrent right-sided CC compared to those with resection for recurrent left-sided CC (5-year: 42.2 vs 71%; P = 0.03).

CONCLUSION

Surgical resection undoubtedly improved survival after recurrence, however, patients with surgical resection for recurrent right-sided CC tended to have a worse prognosis.

Interleukins 4 and 13 and Their Receptors Are Differently Expressed in Gastrointestinal Tract Cancers, Depending on the Anatomical Site and Disease Advancement, and Improve Colon Cancer Cell Viability and Motility

Immunosuppressive interleukins (IL)-4 and 13 may directly promote cancer but neither their status nor role in gastrointestinal tract is clarified. We aim at quantifying ILs and their receptors in paired normal-tumor samples (n = 49/51) and sera (n = 263), using immunoassays and RTqPCR, and screening for their effect on colonic cancer cells. Both ILs were elevated locally at protein level in all cancers but only IL13 transcripts in colon were upregulated. Interleukin and their receptor expression reflected cancer pathology to varying degrees, with the association frequently inverse and manifested in non-cancerous tissue. Positive correlation with cancer-promoting genes BCL2, BCLxL, HIF1A, VEGFA, ACTA2, CCL2, PTGS2, and CDKN1A, but not Ki67, was demonstrated, particularly for ILs' receptors. Circulating IL-4 was elevated in all, while IL-13 only in colorectal or esophageal cancers, reflecting their advancement. IL4Ra and IL13Ra1 transcripts were downregulated by hypoxia and, in Caco-2, also by IL-4. Interleukin stimulation slightly improved colonic cancer cell viability, weakly upregulating BCL2 and Ki67 in HCT116 and HT-29. It affected cell motility more markedly and was consistently accompanied by upregulation of claudin-2. Gastrointestinal tract cancers are associated with IL-4 and IL-13 upregulation, which may facilitate cancer growth. Targeting both interleukins as an antineoplastic strategy warrants further investigation.

Rightward shift in colorectal cancer: experience in 1101 patients

BACKGROUND

In the past decades the right colon cancer showed a higher incidence rate than left colon cancer. This trend is known as "proximal shift" or "rightwards shift." We evaluated rightward shift phenomenon in our region.

METHODS

We collected data from 1101 colorectal cancer patients who underwent curative surgery at Parma University Hospital from 01 January 2004 through 01 January 2018. We divided patients into seven subgroups according to the time of surgery to evaluate epidemiological changes through the years of colon cancer.

RESULTS

We found a non-linear rightward shift trend of CRC. The incidence of RCC was the 40% between 2004-2005 and 51% in the biennium 2016-2017 (60% in 2012-2013 and 57% in 2014-2015). The patients with RCC were significantly older than patients with LCC. RCCs have poor differentiated tumors. Metastatic disease showed a similar distribution both in left and right CRCs. Peritoneum was the most common metastasis location from right-sided colon cancer.

CONCLUSIONS

Data suggest the existence of two different tumor entities in CRC between right-sided colon cancer and left-sided colon cancer. The proximal shift may be a reflection of improved screening programs, diagnostic accuracy and population aging. Ethnicity, gender, diet, environment, and socioeconomic status contribute to CRC incidence and prevalence in different regions.

Left colon as a novel high-risk factor for postoperative recurrence of stage II colon cancer

Background

It is not clear whether stage II colon and rectal cancer have the same risk factors for recurrence. Thus, the purpose of this study was to identify the risk factors for postoperative recurrence in stage II colorectal cancer.

Patients and methods

We retrospectively analyzed the data of 990 patients who had undergone radical surgery for stage II colorectal cancer. Patients’ pathological features and characteristics including age, sex, family history, body mass index, tumor diameter, gross type of tumor, infiltration degree (T3/T4), tumor grade, perineural invasion, vascular invasion, lymphatic invasion, pathologic examination of lymph node number, and preoperative carcinoembryonic assay (CEA) level was compared between patients with and without recurrence. Finally, the prediction of the left and right colons was analyzed.

Results

The mean ages of the colon cancer and rectal cancer patients were 69.5 years and 66.4 years, respectively. In total, 508 (82.1%) and 285 (76.8%) patients were treated laparoscopically for colon cancer and rectal cancer, respectively, with median follow-up periods of 42.2 months and 41.8 months, respectively. Forty-four recurrences occurred in both the colon cancer (7.1%) and rectal cancer (11.9%) groups. The preoperative serum CEA level and T4 infiltration were significantly higher in recurrent colorectal cancer patients. The postoperative recurrence rate of left colon cancer (descending colon, sigmoid colon) was higher than that of right colon cancer (cecum, ascending colon, transverse colon) (OR 2.191, 95% CI 1.091–4.400, P = 0.027). In COX survival factor analysis of colon cancer, the left colon is one of the independent risk factors (risk ratio 5.377, 95% CI 0.216–0.88, P = 0.02). In disease-free survival (DFS), the left colon has a relatively poor prognosis (P = 0.05). However, in the COX analysis and prognosis analysis of OS, no difference was found between the left colon and the right colon.

Conclusion

Preoperative CEA and depth of infiltration (T4) are high-risk factors associated with recurrence and are prognostic factors in stage II colorectal cancer. Left colon is also a risk factor for postoperative recurrence of stage II colon cancer.

A meta-analysis of serological thymidine kinase 1 as a marker for colorectal benign and malignant tumor risk assessment

The present study investigated whether a concentration of serum thymidine kinase 1 (STK1p) could be used to distinguish between healthy individuals, patients with colorectal benign tumors and individuals with colorectal cancer (CRC). The effectiveness of surgery on patients with CRC was monitored. A total of 20 publications containing patients with CRC (n=1,836), patients with colorectal benign tumors (n=774) and healthy controls (n=1,701) were analysed in the present meta-analysis. The publications were collected from PubMed, Embase, CENTRAL, CNKI, Wanfang, VIP and SinoMed databases from January 1, 2009 until August 31, 2019. Articles were analyzed according to sensitivity (Forest plot) and publication bias (Begg's plot, Egger's linear regression) using fixed or random effect models to calculate the weighted mean difference. Study quality was checked using the Newcastle-Ottawa Scale Document Quality Assessment Scale. The meta-analysis followed the PRISMA statement. The results revealed that STK1p significantly distinguished healthy individuals and those with colorectal benign tumors from patients with CRC, and from patients with benign tumors (P<0.000001). STK1p levels also decreased by 40% following surgery (P<0.0001), which corresponded to half-life of ~1 month. The quality of the present study was high and no bias was identified among publication. It was concluded that STK1p was a reliable biomarker for the early detection of benign lesions, which may therefore prevent their future development into colorectal malignancies. STK1p may also be used for the clinical dynamic monitoring of the effectiveness of surgery in patients with CRC. Combining STK1p with colorectal-associated biomarkers, in addition to the determination of tumor stage and grade may therefore be of use.

Microbiome in Colorectal Cancer: How to Get from Meta-omics to Mechanism?

Mounting evidence from metagenomic analyses suggests that a state of pathological microbial imbalance or dysbiosis is prevalent in the gut of patients with colorectal cancer. Several bacterial taxa have been identified of which representative isolate cultures interact with human cancer cells in vitro and trigger disease pathways in animal models. However, how the complex interrelationships in dysbiotic communities may be involved in cancer pathogenesis remains a crucial question. Here, we provide a survey of current knowledge of the gut microbiome in colorectal cancer. Moving beyond observational studies, we outline new experimental approaches for gaining ecosystem-level mechanistic understanding of the gut microbiome's role in cancer pathogenesis.

Immunological Differences Between Right-Sided and Left-Sided Colorectal Cancers: A Comparison of Embryologic Midgut and Hindgut

Purpose

There are known differences in embryology, clinical symptoms, incidences, molecular pathways involved, and oncologic outcomes of right-sided and left-sided colorectal cancers. However, immunologic study has only been characterized for healthy adults. The present study was designed to identify differences in immune cell populations in patients with right-sided and left-sided colorectal cancers.

Methods

A total of 35 patients who underwent colorectal resection for cancer between November 2016 and August 2017 at a tertiary teaching hospital were enrolled in this study. Patients were excluded if they had a disease affecting their immune system. Populations of immune cells, including mucosal-associated invariant T (MAIT), gamma delta T, invariant natural killer T, T, natural killer, and B cells, were measured in the peripheral blood and cancer tissues using flow cytometry, and then assessed based on the origin of the colorectal cancer.

Results

Fifteen had right-side and 20 had left-side colorectal cancer. There were no significant differences between the 2 cohorts for patient characteristics including pathologic stage. Peripheral blood from patients with right-side colon cancers contained fewer MAIT (0.87% right-side vs. 1.74% left-side, P = 0.028) and gamma delta T cells (1.10% right-side vs. 3.05% left-side, P = 0.002). Although the group with right-side colorectal cancer had more MAIT cells in cancer tissues (1.71% vs. 1.00%), this difference was not statistically significant.

Conclusion

There is a difference in population sizes of immune cells in blood between patients with right-sided and leftsided colon cancers. The immune cell composition was determined to be distinct based on embryologic origin.

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.

Clinical significance of MLH1/MSH2 for stage II/III sporadic colorectal cancer

BACKGROUND

The development of colorectal cancer (CRC) is a complicated multistep process that involves an accumulation of mutations in tumor suppressor genes and oncogenes. In the process of DNA replication, base mismatch often occurs due to various factors leading to abnormal expression of mismatch repair genes (MMR), among which MLH1 and MSH2 are the most important. Recently, numerous studies indicated that MLH1/MSH2 phenotype is associated with CRC. We wanted to elucidate the role of MLH1/MSH2 in the prediction and prognosis of CRC through long-term clinical observation.

AIM

To evaluate the prognostic and predictive significance of MLH1/MSH2 in patients with stage II-III CRC using immunohistochemical analysis and GeneScan.

METHODS

Specimens from 681 patients with CRC (395 stage II and 286 stage III, 387 males and 294 females) who underwent curative surgical resection from 2013 to 2016 were tested. Immunohistochemistry was used to analyze MMR status and the microsatellite status of 133 patients was determined by GeneScan analysis.

RESULTS

Five hundred and fifty (80.76%) patients were MLH1/MSH2 positive and 131 (19.24%) were negative by immunohistochemistry. MLH1/MSH2-positive tumors were significantly more frequent in the colon than in the rectum, and had poor differentiation and less mucin production (P < 0.05). Patients of different groups did not differ in terms of age, gender, tumor size, tumor stage, lymphocytic infiltration, or circumscribed margin. MLH1/MSH2-negative patients had a more favorable OS than MLH1/MSH2-positive patients (P < 0.001). Univariate and multivariate analyses demonstrated MLH1/MSH2 expression as an independent prognostic and predictive factor for stage II/III CRC. MLH1/MSH2 expression was a strong prognostic factor in all patients [P < 0.001, hazard ratio (HR) = 4.064, 95%CI: 2.241–7.369]. Adjuvant chemotherapy had a greater correlation with survival advantage in MLH1/MSH2-negative patients with stage III disease (P < 0.001, HR = 7.660, 95%CI: 2.974–15.883). However, patients with stage II disease or MLH1/MSH2-positive patients with stage III disease did not benefit from adjuvant chemotherapy. GeneScan analysis demonstrated that among 133 patients, 105 (78.95%) were microsatellite stable, and 28 (21.05%) had microsatellite instability (MSI), including 18 (13.53%) with high MSI and 10 (7.52%) with low MSI. This is consistent with the immunohistochemical results.

CONCLUSION

MLH1/MSH2 phenotype constitutes a pathologically and clinically distinct subtype of sporadic CRC. MLH1/MSH2 is an independent prognostic and predictive factor for outcome of stage II-III CRC.

Clinical and prognostic differences between surgically resected right-sided and left-sided colorectal cancer

PURPOSE

A growing body of evidence suggests that right-sided colorectal cancer (RCRC) differs from left-sided colorectal cancer (LCRC) in certain clinicopathological features. Therefore, we investigated the difference between RCRC and LCRC in a series of 899 patients.

METHODS

We reviewed data retrospectively, from 899 patients who underwent R0-resection for stage II and III CRC and compared the clinicopathological factors between patients with RCRC and LCRC.

RESULTS

The patients with RCRC tended to be older, more likely female, with a larger tumor, higher pathological T stage, and a greater proportion of their tumors were poorly differentiated adenocarcinoma, mucinous adenocarcinoma, or signet ring cell carcinoma than the patients with LCRC,. Recurrence-free survival (RFS) of the patients with RCRC tended to be higher than that of the patients with LCRC and was significantly better among patients with stage II cancer. The overall survival (OS) was similar for patients with RCRC and LCRC, irrespective of cancer stage.

CONCLUSION

Compared with the patients with LCRC, those with RCRC had several oncologically unfavorable factors, with better RFS in stage II and similar OS in stages II and III. These results suggest that the biological aggressiveness of RCRC is lower than that of LCRC in stage II; however, it can increase after relapse.

Prognostic factors and patterns of recurrence after emergency management for obstructing colon cancer: multivariate analysis from a series of 2120 patients

PURPOSE

At equal TNM stage, obstructing colon cancer (OCC) is associated with worse prognosis in comparison with uncomplicated cancer. Our aim was to identify prognostic factors of overall (OS) and disease-free survival (DFS) in patients treated for OCC.

METHODS

From 2000 to 2015, 2325 patients were treated for OCC in French surgical centers, members of the French National Surgical Association (AFC). Patients with palliative management were excluded. The main endpoints were OS and DFS. A multivariate analysis, using Cox proportional hazards regression model, was performed to determine independent prognostic factors.

RESULTS

The cohort included 2120 patients. The median of follow-up was 13.2 months. In multivariate analysis, age > 75 years, ASA score ≥ 3, ECOG score ≥ 3, right-sided colon cancer, presence of synchronous metastases, anastomotic leakage, and absence of adjuvant chemotherapy were independent OS factors. Age > 75 years, ASA score ≥ 3, right-sided colon cancer, presence of synchronous metastases, and absence of postoperative chemotherapy were independent factors of poor OS after exclusion of patients who died postoperatively. Age ≥ 75 years, ASA score ≥ 3, ECOG score ≥ 3, right-sided colon cancer, lymph node involvement, presence of vascular, lymphatic or perineural invasion, less than 12 harvested lymph nodes, and absence of adjuvant chemotherapy were independent DFS factors.

CONCLUSIONS

Management of OCC should take into account prognostic factors related to the patient (age, comorbidities), tumor location, and tumor stage. Adjuvant chemotherapy administration plays an important role. For patients undergoing initial defunctionning stoma, neoadjuvant chemotherapy could be an option to improve prognosis.

Management of colon cancer at a tertiary referral center in India - Patterns of presentation, treatment, and survival outcomes

AIM

To define the patterns of disease presentation, treatment strategies, and outcomes for patients with colon cancer at a tertiary referral center in India over 1 year period.

MATERIALS AND METHODS

This is a retrospective analysis of a prospectively maintained database. All consecutive patients with proven or suspected colonic adenocarcinoma between July 2013 and July 2014 were evaluated in a dedicated analysed multidisciplinary clinic at the Tata Memorial Hospital, Mumbai. The demography, treatment plan, pathology, stage, and survival data were examined.

RESULTS

The median age of presentation was 49 years with 60.1% male patients. In total, 151 cases (57.4%) underwent treatment with curative intent consisting of surgery with adjuvant chemotherapy as indicated. The rest were offered either palliative chemotherapy (36.9%) or best supportive care (5.7%). Approximately, 70% patients had advanced stage disease (Stage III/IV) at presentation and 41.8% presented with metastatic disease with the liver being the most common site of disease dissemination. With a median follow-up of 29 months, the estimated 3-year disease free survival for patients treated with curative intent was 67.1%. The median progression free survival was 12.3 months for patients treated with palliative intent. The estimated 3-year overall survival was 89.7%, 65.5%, and 22.8% for Stage I/II, Stage III, and Stage IV, respectively.

CONCLUSION

Indian patients with colon cancer, at a tertiary referral center, tend to present at more advanced stages of the disease as compared to the West. However, curative treatment with surgery and chemotherapy offers similar survival outcomes when compared stage for stage.

Blood cell markers that can predict the long-term outcomes of patients with colorectal cancer

Objectives

To identify blood cell markers that predict the long-term outcomes of patients with colorectal cancer.

Methods

Data from 892 stage II and III colorectal cancer patients who underwent R0 resection were included. We analyzed the correlations of the preoperative blood data, previously reported prognostic indices, and clinicopathologic factors with the long-term outcomes, such as relapse-free survival and overall survival, using univariate and multivariate analyses.

Results

Multivariate analysis showed that tumor location, stage, mean corpuscular volume, neutrophil-to-lymphocyte ratio, and lymphocyte-to- monocyte ratio were significantly correlated with relapse-free survival. A mean corpuscular volume ≥80.5 fL, neutrophil-to-lymphocyte ratio ≥5.5, and lymphocyte-to- monocyte ratio <3.4 had hazard ratios for disease relapse between 1.39 and 1.93. The cumulative scores of these three factors were aggregated into a laboratory prognostic score, with a maximum score at 6. The relapse-free survival and overall survival were well stratified by a laboratory prognostic score between 0–3 and 4–6, respectively, independent of the stage.

Conclusion

The mean corpuscular volume, neutrophil-to-lymphocyte ratio, and lymphocyte-to- monocyte ratio can serve as blood cell markers to predict the long-term outcomes of patients who underwent R0 resection for stage II/III colorectal cancer.

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.

Impact of tumor sidedness on survival and recurrence patterns in colon cancer patients

Purpose

Previous studies have reported conflicting results regarding the prognostic value of tumor sidedness in colon cancer. We investigated the oncologic impact of tumor location and examined whether recurrence patterns were related to tumor sidedness in colon cancer patients.

Methods

We identified stage I-III colon adenocarcinoma patients from a prospective colorectal cancer registry at Severance Hospital, Seoul, Korea, who underwent complete mesocolic excision between 2005 and 2012. Adjusted hazard ratios (HRs) and 95% confidence intervals (CI) for predictors of cancer-specific survival (CSS), recurrence-free survival (RFS), and cumulative recurrence at specific anatomic sites were examined using Cox proportional hazard regression analysis.

Results

Overall, 1,912 patients, 1,077 (56.3%) with left-sided colon cancer (LCC), and 835 (43.7%) with right-sided colon cancer (RCC), at a median follow-up of 59 months, were eligible and included in the study. In univariate analysis, similar 5-year CSS and RFS were observed for LCC and RCC in the total patient population, and when stratified by stage for stage I and II patients. For stage III patients, an adjusted Cox regression analysis indicated that RCC patients had a higher risk of cancer-specific mortality (HR, 1.75; 95% CI, 1.07-2.86; P = 0.024) and recurrence (HR, 1.78; 95% CI, 1.22-2.60; P = 0.003). Furthermore, RCC was an independent predictor of peritoneal recurrence (HR, 1.86; 95% CI, 1.05-3.29; P = 0.031) in stage III patients.

Conclusion

RCC correlated with worse CSS and RFS than LCC. In stage III patients, RCC correlated with increased risk of peritoneal recurrence. The reasons for these differences remain to be investigated.

Prognostic impact of tumor location in colon cancer: the Monitoring of Cancer Incidence in Japan (MCIJ) project

BACKGROUND

Colorectal cancer (CRC) is globally one of the most common cancers. Although studies have found a significant prognostic impact of cancer location for right-sided colon cancers compared with those of the left-side, evidence is lacking in a Japanese population. Therefore, we investigated 5-year net survival in colon cancer by tumor site in a Japanese population.

METHODS

Diagnoses obtained between 2006 and 2008 in 21 population-based cancer registries from the Monitoring of Cancer Incidence in Japan (MCIJ) project were used. Colon cancer patients were categorized as having right-sided (C18.0-18.4) or left-sided colon cancer (C18.5-C18.7). We calculated the 5-year net survival for subjects diagnosed from 2006 until 2008 by anatomical subsite according to sex, age groups, tumor stage at diagnosis. We applied the excess mortality model to calculate excess hazard ratios (EHRs) and 95% confidential intervals (CIs) with and without adjustment for age, sex and cancer stages to evaluate the effect of location of colon cancer.

RESULTS

This study analyzed a total of 62,350 colon cancer subjects. Five-year net survivals for subjects with left- and right-sided colon cancer were 74.0% (95% CI, 73.4-74.7%) and 70.4% (95% CI, 69.7-71.0%), respectively. Compared with left-sided colon cancers, the EHR for right-sided colon cancers was 1.20 (95% CI, 1.16-1.25) after adjustment for age, sex and stage.

CONCLUSION

Our study found that the net survival for right-sided colon cancer was significantly lower than that for left-sided colon cancer. The anatomical site of cancer in the colon might be an important stratification factor in future studies of colon cancer.

Does the Different Locations of Colon Cancer Affect the Oncologic Outcome? A Propensity-Score Matched Analysis

PURPOSE

We evaluate the prognostic value of primary tumor location for oncologic outcomes in patients with colon cancer (CC).

METHODS

CC patients treated with curative surgery between 2009 and 2012 were classified into 2 groups: right-sided colon cancer (RCC) and left-sided colon cancer (LCC). Recurrence-free survival (RFS) and overall survival (OS) were examined based on tumor stage. Propensity scores were created using eight variables (age, sex, T stage, N stage, histologic grade, presence of lymphovascular invasion/perineural invasion, and microsatellite instability status).

RESULTS

Overall, 2,329 patients were identified. The 5-year RFSs for RCC and LCC patients were 89.7% and 88.4% (P = 0.328), respectively, and their 5-year OSs were 90.9% and 93.4% (P = 0.062). Multivariate survival analyses were carried out by using the Cox regression proportional hazard model. In the unadjusted analysis, a marginal increase in overall mortality was seen in RCC patients (hazard ratio [HR], 1.297; 95% confidence interval [CI], 0.987-1.704, P = 0.062); however, after multivariable adjustment, similar OSs were observed in those patients (HR, 1.219; 95% CI, 0.91-1.633; P = 0.183). After propensity-score matching with a total of 1,560 patients, no significant difference was identified (P = 0.183). A slightly worse OS was seen for stage III RCC patients (HR, 1.561; 95% CI, 0.967-2.522; P = 0.068) than for stage III LCC patients. The 5-year OSs for patients with stage III RCC and stage III LCC were 85.5% and 90.5%, respectively (P = 0.133).

CONCLUSION

Although the results are inconclusive, tumor location tended to be associated with OS in CC patients with lymph node metastasis, but it was not related to oncologic outcome.

Female Sex and Right-Sided Tumor Location Are Poor Prognostic Factors for Patients With Stage III Colon Cancer After a Curative Resection

Purpose

Stage-IIIC colon cancer is an advanced disease; however, its oncologic outcomes and prognostic factors remain unclear. In this study, we aimed to determine the predictors of disease-free survival (DFS) in patients with stage-IIIC colon cancer.

Methods

From a multicenter database, we retrospectively enrolled 611 patients (355 men and 256 women) who had undergone a potentially curative resection for a stage-IIIC colon adenocarcinoma between 2003 and 2011. The primary end-point was the 5-year DFS.

Results

The median age was 62 years; 213 and 398 patients had right-sided colon cancer (RCC) and left-sided colon cancer (LCC), respectively. The 5-year DFS in all patients was 52.0%; median follow-up time was 35 months (range, 1–134 months). A multivariate Cox regression revealed that female sex (hazard ratio [HR], 1.50; 95% confidence interval [CI], 1.19–1.90; P < 0.01), right-sided tumor location (HR, 1.65; 95% CI, 1.29–2.11; P < 0.01), lymphatic invasion (HR, 1.52; 95% CI, 1.08–2.15; P < 0.01) and a high (≥0.4) metastatic lymph node ratio (HR, 3.72; 95% CI, 2.63–5.24; P < 0.01) were independent predictors of worse 5-year DFS. Female patients with RCC were 1.79 fold more likely to experience recurrence than male patients with LCC.

Conclusion

Female sex and right-sided tumor location are associated with higher tumor recurrence rates in patients with stage-IIIC colon cancers. Aggressive treatment and close surveillance should be planned for patients in these groups.

Prognostic significance of primary tumor localization in stage II and III colon cancer

AIM

To investigate the effects of tumor localization on disease free survival (DFS) and overall survival (OS) in patients with stage II-III colon cancer.

METHODS

This retrospective study included 942 patients with stage II and III colon cancer, which were followed up in our clinics between 1995 and 2017. The tumors from the caecum to splenic flexure were defined as right colon cancer (RCC) and those from splenic flexure to the sigmoid colon as left colon cancer (LCC).

RESULTS

The median age of the patients was 58 years (range: 19-94 years). Male patients constituted 54.2%. The rates of RCC and LCC were 48.4% (n = 456) and 51.6% (n = 486), respectively. During the median follow-up of 90 mo (range: 6-252 mo), 14.6% of patients developed recurrence and 9.1% of patients died. In patients with stage II and III disease with or without adjuvant therapy, DFS was similar in terms of primary tumor localization (stage II; P = 0.547 and P = 0.481, respectively; stage III; P = 0.976 and P = 0.978, respectively). In patients with stage II and III disease with or without adjuvant therapy, OS was not statistically significant with respect to primary tumor localization (stage II; P = 0.381 and P = 0.947, respectively; stage III; P = 0.378 and P = 0.904, respectively). The difference between median OS of recurrent RCC (26 ± 6.2 mo) and LCC (34 ± 4.9 mo) cases was eight months (P = 0.092).

CONCLUSION

Our study showed no association of tumor localization with either DFS or OS in patients with stage II or III colon cancer managed with or without adjuvant therapy. However, post-recurrence OS appeared to be worse in RCC patients.

Characteristics of right-sided colonic neoplasia and colonoscopy barriers limiting their early detection and prognosis: a review of the literature

Colonoscopy provides less protection from colorectal cancer in the right colon than the left. Areas covered: This review examines patient outcomes and colonoscopy success rates to identify factors that limit the protective effect of colonoscopy in the right colon. The MEDLINE and Embase databases were searched for literature from 2000 onwards, on the long-term outcomes and differences in screening practice between the right and left colon. In total, 12 systematic reviews (including nine meta-analyses) and 44 primary data records were included. Differences in patient outcomes and colonoscopy practice were identified between the right and left colon, suggesting that several factors, many of which disproportionally affect the right colon, impact lesion detection rates. Shorter withdrawal times reduce detection rates, while longer times significantly increase detection; mostly of adenomas in the right colon. Colonoscope attachments often only show a significant improvement in detection rates in the right colon, suggesting detection is more challenging due to visibility of the right colonic mucosa. Higher bowel cleansing grades significantly improve detection rates in the right colon compared to the left. Expert commentary: These findings confirm the need for continued improvement of colonoscopy effectiveness, and obligatory quality assessment, overall and especially in the right colon.

Subsite heterogeneity in the profiles of circulating cytokines in colorectal cancer

Colorectal cancers (CRCs) are treated as one entity but are in fact a heterogeneous group of diseases. If not addressed, subsite-associated variability may interfere with mechanism-targeted therapies and accuracy of potential CRC biomarkers. Little is known about the contribution of systemic inflammatory and immune mediators to subsite heterogeneity in CRC. Our purpose was to compare the profiles of key cytokines between right and left colonic and rectal CRCs. Using Luminex xMAP® technology, serum concentrations of eotaxin, IL-1β, IL-1ra, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12(p70), IL-13, IL-15, IL-17, IFNγ, IP-10, FGF-2, G-CSF, GM-CSF, MCP-1, MIP-1α and β, PDGF-BB, RANTES, TNFα, and VEGF-A were determined in 104 CRC patients. We found the concentrations of IL-12(p70), IL-10, IL-1ra, IL-4, IL-6, IL-7, IL-8, G-CSF and TNFα to be significantly higher in right-sided and GM-CSF in left-sided than rectal CRCs. The concentrations of IFNγ and MIP-1α were significantly higher in right-sided CRCs as compared to cancers of other locations combined. In turn, MIP-1β was higher in rectal CRCs as compared to colon cancers. Taken together, our results show subsite heterogeneity of CRC cancers in terms of systemic inflammatory and immune responses that ought to be taken into account when attempting immunotherapy or developing biomarkers. Additionally, more pronounced T_H2 response accompanied by T_H1 immunity and more prominent tumor-promoting inflammation in CRC patients with primary tumors originating from right-sided colon may constitute a molecular background of unfavorable prognosis associated with this location.

Difference Between Left-Sided and Right-Sided Colorectal Cancer: A Focused Review of Literature

Colorectal cancer is the third most common cancer worldwide with a high mortality rate at the advanced stages. However, colorectal cancer is not a single type of tumor; its pathogenesis depends on the anatomical location of the tumor and differs between right side and left side of the colon. Tumors in the proximal colon (right side) and distal colon (left side) exhibit different molecular characteristics and histology. In the right-sided tumors, mutations in the DNA mismatch repair pathway are commonly observed; and these tumors generally have a flat histology. In the left-sided tumors, chromosomal instability pathway-related mutations, such as KRAS, APC, PIK3CA, p53 mutations are observed and these tumors demonstrate polypoid-like morphology. Therapy responses are totally different between these tumor entities. Left-sided colorectal cancer (LCRC) patients benefit more from adjuvant chemotherapies such as 5-fluorouracil (5-FU)-based regimes, and targeted therapies such as anti- epidermal growth factor receptor (EGFR) therapy, and have a better prognosis. Right-sided colorectal cancer (RCRC) patients do not respond well to conventional chemotherapies, but demonstrate more promising results with immunotherapies because these tumors have high antigenic load. For the development of effective therapy regimes and better treatment options, it is essential to evaluate right-sided and left-sided tumors as separate entities, and design the therapy regime considering the differences between these tumors.