Factors Affecting Survival in Patients with Colorectal Cancer in Shiraz, Iran

Association between muscle mass and overall survival among colorectal cancer patients at tertiary cancer center in the Middle East

Recent reports have shown that pre-treatment low muscle mass may lead to poorer outcomes for cancer patients. We explored the correlation between Visceral Adipose Tissue (VAT), Subcutaneous Adipose Tissue (SAT), and Muscle Mass (MM) as measured by CT scans, and overall survival (OS) following diagnosis of colorectal cancer (CRC). We conducted a retrospective review of medical records and CT scans of patients diagnosed with CRC between 2007 and 2018. Demographics, pathology, and clinical parameters were collected. Using Image-J software, we measured VAT, SAT, and MM. Survival rates were analyzed using Kaplan-Meier curves, and prognostic factors were assessed using multivariate Cox regression. Analysis included 408 patients with a mean age of 56.9 years and a median follow-up of 93.3 months. Colon and rectum/rectosigmoid colon cancers were equally distributed. The 5-year OS rate was 67.8%. There was no significant difference in OS rates based on SAT or VAT. However, higher MM was associated with a improved 5-year OS rate. Factors such as age, stage, grade, and surgery were also associated to OS rates. These findings suggest that higher muscle mass may lead to better outcomes for CRC patients, highlighting the potential impact of exercise and nutritional interventions on patient outcomes.

Rectal cancer survival and prognostic factors in Iranian population: A retrospective cohort study

BACKGROUND

Rectal cancer (RC) poses a significant global health challenge, causing substantial morbidity and mortality. This study aims to investigate the survival rates of RC patients and identify the factors that influence their survival. The study considers demographic characteristics, tumor features, and treatment received as the factors under consideration.

METHODS

A retrospective analysis was conducted on the medical records of 593 RC patients. Data were collected through a comprehensive review of medical records and conducting telephone interviews. Survival rates were estimated using the life table method, and subgroup comparisons were performed using the log-rank test. Cox regression analysis was utilized to assess the independent associations between RC survival time and various covariates.

RESULTS

The study cohort comprised 593 RC patients, with a predominantly male representation. The mean age at diagnosis was 58.18 years, and the majority of patients (78.6 %) underwent surgical interventions. The median age at symptom onset and diagnosis were 58 and 59 years, respectively. Survival rates at 1st, 3rd, 5th, and 10th years were estimated to be 85 %, 59 %, 47 %, and 36 %, respectively. Statistical analysis revealed several significant prognostic factors, including age, education, symptoms, and cancer stage. In the multivariate Cox proportional-hazards analysis, advanced regional stage (HR = 1.54, 95 % CI, 1.13-2.08), presence of metastasis (HR = 3.73, 95 % CI, 2.49-5.58), and age over 70 (HR = 1.65) were associated with a higher risk of mortality.

CONCLUSION

Given the alarming prognosis of RC observed in the study area and the significant delay between symptom onset and diagnosis, it is crucial to address this issue and potentially improve the survival rates of RC patients.

Colorectal cancer survival disparities in the five regions of Georgia

BACKGROUND/OBJECTIVE

The objective of this study was to examine 5-year colorectal cancer survival rates. We also determined whether demographics, tumor characteristics, and treatment modality were associated with 5-year CRC survival in the Clayton, West Central, East Central, Southeast, and Northeast Georgia regions because the significant higher CRC mortality rates in these regions in comparison to the overall rates in the State of Georgia.

METHODS

We conducted a retrospective cohort analysis using data from the 1975-2016 Surveillance, Epidemiology, and End Results program aggregated CRC patients to these five regions. Five-year CRC survival was calculated and stratified by the five regions of Georgia, using the Kaplan-Meier method with log-rank test. Cox proportional hazard regression was used to examine the mentioned association in these five regions.

RESULTS

Among 11,023 CRC patients, 5-year CRC survival was lowest in Clayton (65.9%) compared to the West Central (69.0%), East Central (68.2%), Southeast (70.5%), and Northeast regions (69.5%) (p-value = 0.02). In multivariable analysis, greater risk of CRC death was found in the Clayton region compared to the West Central (HR, 1.12; 95%, 1.00-1.25) region when adjusting for demographics, tumor characteristics, and treatment modality. Among Clayton Georgians, age of 75+ years (HR, 2.13; 95%, 1.56-2.89), grade 3 & 4 tumors (HR, 2.22; 95%, 1.64-3.00), and distant stage (HR, 20.95; 95%, 15.99-27.45) were negatively associated with CRC survival.

CONCLUSION

We observed place-based differences in CRC survival with significantly lower survival rates in the Clayton region. Factors associated with higher risk of CRC death include older age at diagnosis, high-grade tumors, and distant stage CRC among Clayton Georgians. Our study provides important evidence to all relevant stakeholders in furthering the development of culturally tailored CRC screening interventions aimed at CRC early detection and improved outcomes.

EPIDEMIOLOGICAL AND MOLECULAR EVALUATION OF BRAF, KRAS, NRAS GENES, AND MSI IN THE DEVELOPMENT OF COLORECTAL CANCER

BACKGROUND AND OBJECTIVES

KRAS, NRAS, BRAF Mutations and microsatellite instability (MSI) can be associated with Colorectal Cancer (CRC) development.

MATERIAL AND METHODS

We evaluated 828 medical records of CRC patients from a school hospital from January/2016 to December/2020. Variables such as age, gender, ethnicity, literacy level, smoking, alcoholism, primary anatomical site, tumor staging, presence of BRAFV600E, KRAS, NRAS and MSI mutations, survival and metastasis were identified. The statistical analyses were performed (p<0.05 is significant.

RESULTS

There was a predominance of males (51.93%), whites (90.70%), low education (72.34%), smokers (73.79%), and non- alcoholics (79.10%). Rectum was the most affected site (42.14%), advanced tumor stage was most prevalent (62.07%), and metastasis occurred in (64.61%). Of the enrolled patients; 204 were investigated for BRAF mutation and detected in (2.94%); 216 for KRAS gene and detected in (26.08%); 210 for NRAS gene, and detected in (25.36%); 370 for MSI, and detected in (44.68%). A significant association of CRC with NRAS mutation and alcohol habit (p = 0.043) was observed. The presence of MSI was associated with primary site proximal colon (p<0.000), distal colon (p=0.001) and rectum (p=0.010).

CONCLUSION

Patients with CRC are male, over 64 years old, white, with low education, smokers and non-alcoholics. The most affected primary site is rectum in advanced stage with metastasis. CRC is associated with NRAS mutation and alcohol habit, there is increased risk for primary site of proximal colon and MSI; decreased risk for distal colon and rectum in the presence of MSI mutation.

Analysis of Prognostic Factors of Rectal Cancer and Construction of a Prognostic Prediction Model Based on Bayesian Network

Background

The existing prognostic models of rectal cancer after radical resection ignored the relationships among prognostic factors and their mutual effects on prognosis. Thus, a new modeling method is required to remedy this defect. The present study aimed to construct a new prognostic prediction model based on the Bayesian network (BN), a machine learning tool for data mining, clinical decision-making, and prognostic prediction.

Methods

From January 2015 to December 2017, the clinical data of 705 patients with rectal cancer who underwent radical resection were analyzed. The entire cohort was divided into training and testing datasets. A new prognostic prediction model based on BN was constructed and compared with a nomogram.

Results

A univariate analysis showed that age, Carcinoembryonic antigen (CEA), Carbohydrate antigen19-9 (CA19-9), Carbohydrate antigen 125 (CA125), preoperative chemotherapy, macropathology type, tumor size, differentiation status, T stage, N stage, vascular invasion, KRAS mutation, and postoperative chemotherapy were associated with overall survival (OS) of the training dataset. Based on the above-mentioned variables, a 3-year OS prognostic prediction BN model of the training dataset was constructed using the Tree Augmented Naïve Bayes method. In addition, age, CEA, CA19-9, CA125, differentiation status, T stage, N stage, KRAS mutation, and postoperative chemotherapy were identified as independent prognostic factors of the training dataset through multivariate Cox regression and were used to construct a nomogram. Then, based on the testing dataset, the two models were evaluated using the receiver operating characteristic (ROC) curve. The results showed that the area under the curve (AUC) of ROC of the BN model and nomogram was 80.11 and 74.23%, respectively.

Conclusion

The present study established a BN model for prognostic prediction of rectal cancer for the first time, which was demonstrated to be more accurate than a nomogram.

Report of 13-year survival of patients with colon and rectal cancers; lessons from Shiraz colorectal cancer surgery registry system of a level three medical center

Background

Colorectal cancer (CRC) is the second most common cancer in women and the third most common cancer in men worldwide, with an increasing trend in its incidence in Asian countries. In the present study, we aimed to describe the 13-year results of patients with CRC based on the Shiraz Colorectal Cancer Surgery (SCORCS) registry system in patients with a pathologically confirmed diagnosis of colon cancer (CC) and rectal cancer (RC) undergoing surgery.

Methods

Between 2007 and 2020, 811 patients, including 280 patients with CC and 531 patients with RC, registered in SCORCS, were included in the present study. The information collected for this study included demographic characteristics of the patients, primary clinical presentations, laboratory findings before surgery, radiologic and colonoscopy results, and surgical procedures. Death was confirmed by the physician as “CRC-related”. The data were analyzed by SPSS software version 21; life table and Kaplan-Meier curve were used for evaluating the overall survival, recurrence, and metastasis rates and Log-Rank test or Breslow test to check significant differences between the subgroups. The Cox proportional regression model was fitted to evaluate the prognostic factors of survival recurrence and metastasis.

Results

Laparoscopy was performed in 60% of patients (66% in RC and 51% in CC), laparotomy in 32% (27% in RC and 41% in CC), and 7% required conversion. The median time of follow-up was 29 months in all patients; 28 months in patients with RC, and 33 months in patients with CC; 1, 3, and 5 years’ survival rate was 90, 70, and 63% for all the patients, 89%, 67%, and 58% for RC and 90%, 74%, and 71% for CC, respectively (P = 0.009). The Cox regression analysis revealed tumor stages II, (P = 0.003, HR:2.45, 95% CI;1.34–4.49), III, (P ≤ 0.001, HR:3.46, 95% CI;1.88–6.36) and IV, (P ≤ 0.001, HR:6.28, 95% CI;2.73–14.42) in RC and stage IV, (P = 0.03, HR:9.33, 95% CI;1.1-76.37) in CC were the significant survival prognostic factors. The metastasis and recurrence of the tumors occurred earlier in patients with RC than CC (P = 0.001 and 0.03, respectively).

Conclusions

Long-term follow-up of patients with CRC in an Iranian population indicated the significance of screening for diagnosis of early stages and improved survival of the patients.

Associated Factors of Survival Rate and Screening for Colorectal Cancer in Iran: a Systematic Review

PURPOSE

Colorectal cancer (CRC) is one of the most important cancers, which has various patterns in the world. The aim of this study was to determine the factor associated to survival and looking for screening in Iran.

METHODS

A literature search was conducted using PubMed, Web of Science, Scopus, SID, and Magiran on June 30, 2018. Studies that performed survival analysis and the barrier of screening for colorectal cancer were included in this review.

RESULTS

Fifty-three articles for survival and 11 for screening were included and examined. The important factors of survival are the age, cancer stage, tumor grade, ethnicity, marital status, family history of cancer, smoking, metastasis, and obesity. For barrier of screening, the cost, shame, fear of diagnosis the cancer, absence of clinical symptoms, and time limit were determined.

CONCLUSION

Remarkably, knowledge, attitude, and behaviors about CRC screening in Iran are very moderate to poor. According to diversity of survival rates and low tendency to screening, we need to further and deepen studies of barrier and facilitators of screening.

Prognosis of colorectal cancer in Tikur Anbessa Specialized Hospital, the only oncology center in Ethiopia

Introduction

Colorectal cancer is the third most commonly diagnosed cancer in males and the second in females worldwide. According to the Addis Ababa cancer registry, it is the first in male and fourth in female in Ethiopia. However, there have not been studies on prognostic factors and survival of colorectal cancer. Hence, this study aimed to estimate survival time and identify prognostic factors.

Methods

In this institution based retrospective study, medical records review of 422 colorectal cancer patients and telephone interview was used as sources of data. Survival time was estimated using Kaplan-Meier estimator. Prognostic factors were identified using the multivariable Cox regression model.

Results

Patients diagnosed with rectal cancer had 76% (HR: 1.761, 95% CI: 1.173–2.644) increased risk of dying compared to colon cancer patients. Node positive patients were 3.146 (95% CI: 1.626–6.078) times likely to die compared to node-negative and metastatic cancer were 4.221 (95% CI: 2.788–6.392) times likely to die compared to non-metastatic patients. Receiving adjuvant therapy reduced the risk of death by 36.1% (HR: 0.639 (95% CI: 0.418–0.977)) compared to patients who had an only surgical resection. The median survival time was 39 months and the overall five years survival rate was 33%.

Conclusions

The overall survival rate was low and a majority of the patients were young at presentation. Patient’s survival is largely influenced by the advanced cancer stage at presentation and delays in the administration of adjuvant therapy. Receiving adjuvant therapy was among the good prognostic factors.

SURVIVAL OF PATIENTS WITH COLORECTAL CANCER IN A CANCER CENTER

BACKGROUND

Hospital-based studies recently have shown increases in colorectal cancer survival, and better survival for women, young people, and patients diagnosed at an early disease stage.

OBJECTIVE

To describe the overall survival and analyze the prognostic factors of patients treated for colorectal cancer at an oncology center.

METHODS

The analysis included patients diagnosed with colon and rectal adenocarcinoma between 2000 and 2013 and identified in the Hospital Cancer Registry at A.C.Camargo Cancer Center. Overall 5-year survival was estimated using the Kaplan-Meier method, and prognostic factors were evaluated in a Cox regression model. Hazard ratios (HR) are reported with 95% confidence intervals (CI).

RESULTS

Of 2,279 colorectal cancer cases analyzed, 58.4% were in the colon. The 5-year overall survival rate for colorectal cancer patients was 63.5% (65.6% and 60.6% for colonic and rectal malignancies, respectively). The risk of death was elevated for patients in the 50-74-year (HR=1.24, 95%CI =1.02-1.51) and ≥75-year (HR=3.02, 95%CI =2.42-3.78) age groups, for patients with rectal cancer (HR=1.37, 95%CI =1.11-1.69) and for those whose treatment was started >60 days after diagnosis (HR=1.22, 95%CI =1.04-1.43). The risk decreased for patients diagnosed in recent time periods (2005-2009 HR=0.76, 95%CI =0.63-0.91; 2010-2013 HR=0.69, 95%CI =0.57-0.83).

CONCLUSION

Better survival of patients with colorectal cancer improves with early stage and started treatment within 60 days of diagnosis. Age over 70 years old was an independent factor predictive of a poor prognosis. The overall survival increased to all patients treated in the period 2000-2004 to 2010-2013.

Clinical characteristics and predictors of 5-year survival among colorectal cancer patients in a tertiary hospital in Malaysia

Background

Colorectal cancer is the second most common cancer in Malaysia. Its disease burden is likely to increase over time owing to its current trends in this region. This study was undertaken to determine the 5-year survival rate and prognostic factors for survival in colorectal cancer patients treated in a tertiary hospital, in Malaysia.

Methods

We reviewed the records of colorectal cancer patients treated in Hospital Tuanku Ja'afar Seremban, Malaysia from 2008 to 2012. Survival analysis at five years was performed using the Kaplan-Meier method. Cox proportional hazard regression analysis was carried out to determine the predictors of 5-year colorectal cancer survival.

Results

Of the 275 patients, 43.3% were colon cancers, 51.8% were rectal cancers. Only 2.2% were diagnosed in Stage I. 28.7%, 33.1%, and 16.7% were in Stage II, III and IV respectively; 62/79 (78%) of Stage II patients were in Stage IIb; 15.7% of patients were below the age of 50 and fewer of them presented early (P=0.002). The overall 5-year survival was 46.5%. It was 67.9%, 50.5% and 12.8% for Stage I&II, III and IV patients respectively. Early stage of cancer (P<0.001) and age below the mean (P=0.01) were the most significant factor in predicting better survival. Gender and ethnic group were not associated with late presentation nor survival. Neither was there a difference between colon and rectum cancers nor patients who received elective surgical treatment compared to patients receiving other treatment first (P=0.085).

Conclusions

Late presentation is the most important predictor for poor outcome for colorectal cancer in Seremban. Patients under the age of 50 years present late more often, but do not have poorer survival.

Inhibition of miR-19a partially reversed the resistance of colorectal cancer to oxaliplatin via PTEN/PI3K/AKT pathway

Oxaliplatin is a platinum-based chemotherapeutic drug that is effective and commonly used in the treatment of colorectal cancer (CRC). However, long-term use of oxaliplatin usually induces significant drug resistance. It is urgent to develop strategies to reverse the oxaliplatin resistance to CRC cells. In the present study, we established the model of oxaliplatin-resistant CRC cell lines (SW480/R and HT29/R) through continuous treatment of SW480 and HT29 cells with oxaliplatin. Results of qRT-PCR analysis showed that expression of miR-19a was significantly increased in SW480/R and HT29/R compared to their parental SW480 and HT29. However, combination treatment with anti-miR-19a, an antisense oligonucleotide of miR-19a, was found to resensitize SW480/R and HT29/R cells to oxaliplatin treatment. In the mechanism research, we found that anti-miR-19a increased the expression of PTEN and thus inhibited the phosphorylation of PI3K and AKT in SW480/R and HT29/R cells. As a result, mitochondrial apoptosis induced by oxaliplatin was expanded. We demonstrated that PTEN was the target of miR-19a and inhibition of miR-19a partially reversed the resistance of colorectal cancer to oxaliplatin via PTEN/PI3K/AKT pathway.

Survival Rate of Colorectal Cancer in Eastern Mediterranean Region Countries: A Systematic Review and Meta-Analysis

Colorectal cancer (CRC) is the second most common cause of cancer-related deaths worldwide. Survival rates are among the most important factors in quality control and assessment of treatment protocols. This study was aimed to assess the survival rate of colorectal cancer in Eastern Mediterranean Region Countries. In the present study we comprehensively searched 6 international databases including PubMed/Medline, ProQuest, Scopus, Embase, Web of Knowledge and Google Scholar for published articles until November 2018. The Newcastle-Ottawa Quality Assessment Form for Cohort Studies was applied to evaluate the quality of included studies. The heterogeneity of papers was assessed with the Cochran Test and I-Square statistics. Meta-regression test was performed based on publication year, sample size and Human Development Index (HDI) of each study. Among the total of 1023 titles found in the systematic search, 43 studies were eligible to be included in the present meta-analysis. According to the results, the 1-year, 3-year and 5-year survival rate of patients with Colorectal Cancer was 88.07% (95% CI, 83.22-92.92), 70.67% (95% CI, 66.40-74.93) and, 57.26% (95% CI, 50.43-64.10); respectively. Furthermore, Meta-regressions did not show significant correlations between survival rate and year, sample size or Human Development Index. Survival rates, especially the 5-year survival rate in the EMRO were less than European countries and the USA. Documented and comprehensive evidence-based findings of the present meta-analysis can be used to enhance policies and outcomes of different medical areas including prophylaxis, treatment and health related objectives in colorectal cancer.

Comparison of risk factors between colon cancer and rectum cancer in a single medical center hospital, Taiwan

INTRODUCTION

Colorectal cancer (CRC) is rapidly increasing in developed countries. In Taiwan, the incidence rate of CRC has increased during the past decade, but the 5-year survival has remained at approximately 63%. In this study, we sought to determine the 5-year survival rate of patients diagnosed with colon and rectum cancer and to determine factors affecting survival.

MATERIAL AND METHODS

All patients from the Taiwan Cancer Database of the medical center hospital in North Taiwan between 2007 and 2013 were identified. Survival analysis was performed using Kaplan-Meier curves, and differences between the curves were analyzed using the log-rank test. Cox proportional hazards regression models were used to analyze survival by each variable.

RESULTS

A total of 869 patients were included: 554 (63.8%) patients had colon cancer and 315 (36.2%) had rectum cancer. The mean survival time was 71.27 ±1.27 months (colon group: 71.90 ±1.58 months; rectum group: 67.88 ±1.95 months). There was no significant difference (p = 0.493) between patients who had colon or rectum cancer. The forward stepwise Cox regression analysis results indicated that perineural invasion, distant metastasis, age, pathological differentiation grade, and obstruction were statistically significant for patients who had CRC, colon cancer or rectum cancer.

CONCLUSIONS

The long-term survival from CRC, colon cancer and rectum cancer remains promising, as 68.66%, 69.11% and 67.90% of patients are alive 5 years after being diagnosed, respectively. Perineural invasion was found to be an important factor related to the survival of patients who have CRC. Thus, early detection of CRC may help improve survival.

Survival Rate of Colorectal Cancer in Iran: A Systematic Review and Meta-Analysis

Background: Different studies have been conducted to estimate the survival rate of colorectal cancer in Iran but there is no overall estimate of the survival rate. The aim of this study was to calculate the pooled 1, 3, and 5-year survival rate of the patients with colorectal cancer in Iran. Methods: To retrieve relevant studies, we conducted a systematic search in Iranian databases, including Iran Medex, Magiran, SID, and international databases such as Medlin/PubMed, Scopus, and Google scholar using “Colorectal Neoplasms” and “Survival Rate” as keywords up to December 1st, 2017. We used random effect model to estimate pooled 1, 3, and 5-year survival rates of the patients with colorectal cancer in Iran. To assess the heterogeneity, we used Chi-squared test at the 5 % significance level (p <0.05) and I2 Index. We used meta-regression and subgroup analysis to find a potential source of heterogeneity. Results: After a systematic search, 196 articles were found, of the 38 studies met the eligibility criteria and are included in our meta-analysis. The pooled 1, 3, and 5-year survival rates in patient with colorectal cancer were 0.84 (95% CI: 0.81-0.87), 0.64 (95%CI: 0.59-0.70), and 0.54 (95%CI: 0.49-0.58) respectively. The 5-year survival rate in the subgroup of women was 0.5 (0.44-0.56) and in male subgroup was 0.44 (0.40-0.48). In a subgroup of the tumor site, the 5-year survival rate in colon cancer was 0.6 (0.49-0.75) and rectum cancer was 0.54 (0.36-0.69). In multivariable models, there was a significant association between years of study and 5-year survival rate as a source of heterogeneity (β = 18.9, P=0.01). Conclusion: According to the results of this study, women had a better survival rate than men, and according to the tumor site, the 5-year survival rate in colon cancer was better than the rectum cancer.

Risk Factors Predicting Colorectal Cancer Recurrence Following Initial Treatment: A 5-year Cohort Study

Purpose:

Recurrence is one of the most important factors influencing survival of colorectal cancer patients.

Subjects and Methods:

In this cohort study, clinical and demographic characteristics of 561 patients with colorectal cancer were collected from 2010 to 2015. Medical records and telephone interviews were used to define the patient’s clinical status including the date of any recurrence during the study period. The multivariate Cox model was used as the main strategy for analyzing data.

Results:

Some 239 (42.6%) patients experienced cancer recurrence during the 5-year follow-up period. Those with an older age at diagnosis had a higher risk of cancer recurrence than their younger counterparts [Hazard Ratio (HR) >70 y /<50 y= 1.65, P=0.01]. Rectal cancer had a greater risk of disease recurrence compared with other tumor sites [HR colon/ rectum=1.53, P=0.02]. Stage 3 cancer had a higher risk than stage 1 cancer [HR stage 3/ stage 1=4.30, P<0.001], and positive lympho-vascular invasion was also a risk factor [HR yes/ no=2.03, P<0.001]. Finally, tumor size, number of dissected lymph nodes, proportion of positive lymph nodes, perineural invasion and type of treatment did not significantly predict recurrence.

Conclusion:

Access to enhanced medical services including cancer diagnosis at an early stage and optimal treatment is needed to improve the survival and quality of life of CRC patients.

Applying Additive Hazards Models for Analyzing Survival in Patients with Colorectal Cancer in Fars Province, Southern Iran

Introduction:

Colorectal cancer (CRC) is a commonly fatal cancer that ranks as third worldwide and third and the fifth in Iranian women and men, respectively. There are several methods for analyzing time to event data. Additive hazards regression models take priority over the popular Cox proportional hazards model if the absolute hazard (risk) change instead of hazard ratio is of primary concern, or a proportionality assumption is not made.

Methods:

This study used data gathered from medical records of 561 colorectal cancer patients who were admitted to Namazi Hospital, Shiraz, Iran, during 2005 to 2010 and followed until December 2015. The nonparametric Aalen’s additive hazards model, semiparametric Lin and Ying’s additive hazards model and Cox proportional hazards model were applied for data analysis. The proportionality assumption for the Cox model was evaluated with a test based on the Schoenfeld residuals and for test goodness of fit in additive models, Cox-Snell residual plots were used. Analyses were performed with SAS 9.2 and R3.2 software.

Results:

The median follow-up time was 49 months. The five-year survival rate and the mean survival time after cancer diagnosis were 59.6% and 68.1±1.4 months, respectively. Multivariate analyses using Lin and Ying’s additive model and the Cox proportional model indicated that the age of diagnosis, site of tumor, stage, and proportion of positive lymph nodes, lymphovascular invasion and type of treatment were factors affecting survival of the CRC patients.

Conclusion:

Additive models are suitable alternatives to the Cox proportionality model if there is interest in evaluation of absolute hazard change, or no proportionality assumption is made.