Clinicopathological Features And Prognostic Analysis Of Left-sided And Right-sided Colorectal Cancer

BackgroundColorectal Cancer(CRC)is a common malignant digestive tract tumor in our country,with number of incidence and death increasing by years.The latest global burden of Cancer data reports in 2020 suggested that new incidence of CRC in our country was about 560 thousand people and the deaths were about 290 thousand people,ranking 2nd and 5th in the spectrum of malignant tumor diseases,respectively.There were new incidence of 1.93 million CRC patients and the number of death with CRC were around 940 thousand people in globe,ranking 3rd in the new malignant tumor cases and 2nd in the leading cause of death.The rectum and sigmoid colon are still the most common sites of CRC,but with the aging of the population,the increasing number of people eating red and processed meat,the increasing obesity rate among young people,and the popularization of colonoscopy screening,the primary tumor location of CRC has shown a trend of proximal position.Since 1990,when Bufill proposed different embryonic origins in the left-side and right-side colorectum,the high heterogeneity of CRC had attracted much attention.Clinically,colorectal cancer is classified into right-side colorectal cancer(RCRC)and left-side colorectal cancer(LCRC)according to the location of splenic flexure.Studies had concluded that CRC was no longer a single kind of disease.LCRC and RCRC behaved differently in the aspects of anatomy,epidemiology,risk factors,molecular biology,tumor immune microenvironment,intestinal flora,clinicopathology,treatment and prognosis.However,in terms of clinicopathological features and prognosis of LCRC and RCRC patients,especially for the prognosis based on different pathological stages,research conclusions were totally different.In order to deepen the understanding of the differences between LCRC and RCRC,this study retrospectively analyzed the clinicopathological and survival data of postoperative CRC patients hospitalized in the First Affiliated Hospital of Zhengzhou University,and performed subgroup analysis on the survival data of LCRC and RCRC patients according to different pathological stages.ObjectiveThe purpose of this study was to retrospectively analyze clinicopathologic features and survival of LCRC and RCRC,to screen the independent risk factors of death in patients with CRC after operation.Exploring the influence of the primary tumor location on the survival of patients with colorectal cancer after operation and performing subgroup analysis on the survival data of LCRC and RCRC patients according to different pathological stages,so as to improve individualized treatment for the patients with CRC of different primary tumor site.MethodsA total of 382 patients with CRC who underwent surgical operation in the first Affiliated Hospital of Zhengzhou University from February 2014 to December 2014 were taken as research objects.There were 141 and 241 cases classified as RCRC and LCRC by splenic flexure.Collecting the general information(gender,age,preoperative intestinal obstruction,diabetes mellitus,history of cholecystectomy,family history of malignant tumor),laboratory data(Hemoglobin,carcinoembryonic antigen),imaging data and postoperative pathological data(primary tumor location,tumor diameter,histological type,differentiation degree,depth of tumor invasion,lymph node metastasis,distant metastasis,neurovascular invasion and cancer nodules),whether they ’were treated with adjuvant chemotherapy and had postoperative recurrence,as well as recording the overall survival time of the patients,which was defined as the time from surgical operation to death or the last follow-up.The cutoff time of follow-up was July 31,2020.Using statistical methods(SPSS 22.0),including t test,χ2 test and rank test to analyze differences between two groups of patients in the clinicopathological features.The Cox proportional hazards model was used to analysis the independent risk factors of death in patients with colorectal cancer.Kaplan-Meier method and log-rank test were used for survival analysis.Results1.There were no statistically significant differences in gender,age of onset between the LCRC and RCRC(P>0.05).Compared with LCRC,RCRC was prone to present preoperative intestinal obstruction(P<0.05).2.The proportion of patients with diabetes(8.5%and 3.7%,OR=2.40),history of cholecystectomy(34.8%and 17.0%,OR=2.60)and family history of malignant tumor(20.6%and 10.8%,OR=2.14)were higher in the RCRC patients than LCRC,and the differences were statistically significant(all P<0.05).3.There were no statistical differences in preoperative carcinoembryonic antigen(CEA)level,neurovascular invasion,cancer nodules,lymph node metastasis,Whether adjuvant chemotherapy and postoperative recurrence between left-side and right-side colorectal cancer(all P>0.05).4.Compared with the LCRC,the RCRC had lower preoperative hemoglobin(Hb)level,larger tumor diameter and was easier to contain mucus,lower differentiation degree,deeper tumor invasion,and tended to have distant metastasis,with statistically significant differences(all P<0.05).5.The median overall survival(OS)of postoperative CRC patients was 64.4 months(95%CI:61.9～66.9 months),and the cumulative survival rates at 1,3,and 5 years were 94.2%,81.3%,and 73.9%,respectively.Multivariate Cox regression analysis showed that primary tumor location in the right-side colorectum,tumor diameter,lymph node metastasis,distant metastasis,without adjuvant chemotherapy and postoperative recurrence were independent risk factors for the OS of CRC patients(all P<0.05).6.The OS of patients with RCRC(59.2 months,95%CI:54.6-63.8 months)was shorter than that of patients with LCRC(66.2 months,95%CI:63.6～68.8 months),the difference was statistically significant(χ2=8.176,P<0.05).The 1-,3-and 5-year cumulative survival rates for LCRC and RCRC were 98.5%,86.7%,79.1%and 87.9%,73.4%,66.1%,respectively.7.The subgroup analysis of different pathological stages for LCRC and RCRC showed that the OS of stage III LCRC was better than that of stage Ⅲ RCRC(66.0 months versus 55.0 months,respectively,χ2=5.044,P<0.05).For stage Ⅰ,stage Ⅱand stage Ⅳ,there were no statistical differences in OS between LCRC and RCRC(P>0.05).Conclusions1.Patients with diabetes,cholecystectomy,or a family history of malignancy have a higher risk of developing RCRC than LCRC.For such patients,it is recommended to perform colonoscopy in time to achieve the purpose of early diagnosis and early treatment if the risk of colorectal cancer is suspected.2.Compared with LCRC,RCRC patients are prone to present preoperative intestinal obstruction and have lower preoperative Hb level,larger tumor diameter.Besides,RCRC patients are easier to contain mucus components and have lower differentiation degree,deeper tumor infiltration,as well as more likely to have distant metastasis.3.The primary tumor location is an important predictor of the prognosis of CRC patients.The OS of patients with RCRC is shorter than that of patients with LCRC.The prognosis of RCRC is worse than LCRC.Moreover,the primary tumor site has different effects on the survival of CRC patients with different pathological stages.