Iranian Journal of

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Background & objectives: Competing risk data is one of the multivarite survival data. Competing risk data can be modelled using copula function. In this study we propose a bayesian modelling approach of competing risk data using the copula function.
Methods: We used the data from colorectal cancer registyrarty in Tehran. After constructing likelihood function using Clayton copula by choosing appropriate prior distribution for parameters, we obtained the posterior distribution of parameters using the Metropolis-Hastings algorithms and Slice sampling.
Results: The results of univariate analysis showed that sex, histology of tumor, extent of wall penetration, lymph node metastasis, distant metastasis and pathological stage of tumor were significantly associated with colon cancer and sex, histology of tumor, lymph node metastasis, distant metastasis and pathological stage of tumor were were significantly related to rectal cancer. In the multivariate analysis, age at diagnosis, tumor grade and distant metastasis were significant prognostic factors for colon cancer and tumor grade and size of the tumor were significant prognostic factors of rectal cancer
Conclusions: As we showed some variables may have different impacts on colon and rectum cancers, consequently, further studies are needed to be conducted considering risk factors of these cancers separately.

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Background & Objectives: Identifying the important influential factors is a great challenge in oncology studies. Decision tree is one of methods that could be used to evaluate the prognostic factors and classifying the patients' homogeneously. This method identifies the main prognostic factors and then determines the subgroups of patients based on those prognostic factors. The aim of this study was to assess the prognostic factors and homogeneous subgroups of colorectal patient through survival tree.
Methods: Data collected from an observational of 739 colorectal patients registered in the cancer registry affiliated to the center of Research Center of Gastroenterology and Liver Disease (RCGLD), Shahid Beheshti Medical University, Tehran, Iran. Death was the interested event and the survival time was calculated from date of diagnosis until occurrence of event (or censoring) in months. Finally we used decision tree based method for classifying and analyzing the data.
Results: Based on our result, decision tree identified four covariates as important prognostic factors in 0.05 significant levels: general stage of cancer, age of diagnosis, histology of tumor and morphology type of tumor. Also patients based on these prognostic factors divided into five homogeneous subgroups. The greater values of measure of separation (SEP) criterion support the appropriateness of this model for such the data.
Conclusion: Decision tree is powerful and intuitive method. It has a key feature that is in addition to evaluate the prognostic factors, provides the homogeneous subgroups for future analysis.

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Background and Objectives: Colorectal cancer, as the third common cancer, is one of the main health problems in Iran. We assessed the burden of colorectal cancer, as one of the high-priority indices, in this cross-sectional study in Iran in 2008.

Methods: CANMOD software was used for calculation. The input data included the population of Iran, all-cause and colorectal cancer mortality rates, and incidence rate of colorectal cancer, which were all obtained from the Iran Statistic Center, Mortality Registry System, and Cancer Registry System.

 Results: The total burden of colorectal cancer according to DALY in Iran in 2008 was 52534 years in the total population. Years of lost life (YLL) amongst males and females were 26455 and 19887 years, respectively. Years lived with disability (YLD) were 3473 and 2719 years for males and females, respectively. The burden of colorectal cancer per 1000 population was 75.4 years for males and 65.7 years for females. The peak age of colorectal cancer burden rate was in the age group 45-79 years.

 Conclusion: The burden of the colorectal cancer in Iran has increased compared to the last study (2003) which is due to the increase in its incidence and the related mortality during this period. Due to the possibility of prevention and effective intervention, this cancer should be a priority in the health care system. However, the final judgment should be made after calculation of the burden of other cancers, diseases, and damages at the country level and their respective rankings.

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Background and Objectives: Colorectal cancer is the fourth leading cause of cancer death worldwide.  Annually 1430000 cases would be diagnosed and half of these people would die of the disease. In Iran, colorectal cancer is the fifth common cancer among men and is the thirdamong women. This study was designed to estimate survival rates for patients with colorectal cancer and related factors.  

Methods: During the 1384 to 1388 years 24,807 patients diagnosed with colorectal cancer were recorded in the Cancer Registry of the Ministry of Health and Medical Education. Age, gender, marital status, education, occupation, place of residence, tumor diagnosis, the clinical and demographic factors in colorectal cancer as effective on survival entered in Aalen’s additive hazard model and diagram Aalen's was used to study the effects of these factors over time. R 3.2.0 software was used for data analysis.

Results: Stage of tumor had a significant association with survival rates. In this study 1 to 5 year survival rate for patients with stage II tumors, was 100%, 98%, 96%, 93% and 93% respectively and for patients with stage III tumors 99%, 97%, 94%, 90% and 84%, respectively.

Conclusion: In spite of using Cox model in survival analysis by many researchers, Aalen’s model may yield new insights in prognostic studies of survival time of patients with colorectal cancer over time. Our results suggest that early detection of patients in primary stage is important to increase survival.

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Background and Objectives: Colorectal cancer is the third most common cancer in men and the second most common cancer in women in the world. The colorectal cancer screening program was conducted in Iran as a pilot in the late 2010 with the aim of reducing the burden of colorectal cancer. The aim of this study was to evaluate the colorectal cancer screening program in Iran.

Methods: This cross-sectional study was conducted on data from the pilot colorectal cancer screening programs. First, the indicators of the colorectal cancer screening program were determined through a comprehensive review of scientific databases, interviews with experts and implementation of pilot evaluation. Then, the indicators were calculated through descriptive analysis using SPSS version 18.

Results: The indicators and their values were as follows: coverage rate 33.04%, participation rate 53.3%, percentage of consulted people 99.6%, percentage of blood samples 37%, percentage of colonoscopy 54.8%, cancer detection rate 2.7%, and polyp detection rate 18.1%. Among people who gave blood samples 1.6% had familial adenomatous polyposis (FAP) syndrome, 43.06% had hereditary no polyposis colorectal cancer (HNPCC) syndrome, and 29% were sporadic cases.

Conclusion: The screening program in Iran has differences with other countries which have affected the indicators.

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Background and Objectives: Colorectal cancer is the fourth most common cancer and the fifth cause of cancer-related mortality in Iran. This study aimed to determine the incidence of colorectal cancer in men and women and to investigate its relationship with the human development index (HDI) and its components in Iranian provinces.
Methods: This ecological study was conducted to assess the correlation between age-specific incidence of colorectal cancer in men and women and the Human Development Index. We used the data of the Iranian Cancer Registry and Statistical Centre of Iran. We used a bivariate correlation method to assess the correlation of ASR and HDI. P values less than 0.05 were considered significant. All reported P-values are two-sided. Statistical analyses were performed using the SPSS software version 23.
Results: The highest incidence of colorectal cancer in men was seen in Tehran (78.16), Eastern Azerbaijan (41.14), and Semnan (62.13), and the highest incidence of colorectal cancer in women was seen in Tehran (47.18), Semnan (80.14), and Eastern Azerbaijan (82.12), respectively. The results showed that the incidence of colorectal cancer in men (r = 0.605) and women (r = 0.661) had a positive significant correlation with the Human Development Index (P<0.001).
Conclusion: The incidence of colorectal cancer was high in provinces with a higher human development index. Therefore, evaluation of the incidence of cancer by the Human Development Index and its components can be used to show a clearer picture of the distribution of cancer in each country and may be useful for cancer prevention plans.

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Background and Objectives: The purpose of this study was to predict the mortality rate of colorectal cancer in Iranian patients and determine the effective factors  on the mortality of patients with colorectal cancer using random forest and logistic regression methods.
 
Methods: Data from 304 patients with colorectal cancer registry from the Gastroenterology and Liver Research Center of Shahid Beheshti University of Medical Sciences during the years 2009 to 2014 were used as a retrospective study. Data analysis was performed using random forest and logistic regression methods. To analyze the data, R software version 3.4.3 was considered.
 
Results: Ten important variables related to colorectal cancer deaths were selected by random forest method. Several criteria such as the area under the characteristic curve (AUC) were used to compare the random forest method with logistic regression. According to both criteria, five important variables ranked by random forest were Cancer stage, age of diagnosis, patient's age, HLA, and degree of differentiation (tumor differentiation). In terms of different criteria, the random forest method had better performance than logistic regression (Area under the ROC curve for random forest and logistic regression methods was: 98%; 80% respectively).
 
Conclusion: Variables such as Cancer stage, age of diagnosis, patient's age, HLA, and degree of differentiation are considered as the most important factors affecting mortality in colorectal cancer, that the patients' longevity can be increased with the early diagnosis of cancer and screening programs.
 

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Background and Objectives: The incidence of colorectal cancer has increased significantly in Iran in recent decades. The pattern of occurrence varies in different populations. A study was conducted to perform a spatial analysis of colorectal cancer and some of its risk factors in Iran using GIS.
 
Methods: The data of this descriptive-analytic study included colorectal cancer incidence as a dependent variable and physical activity, Body Mass Index and smoking as independent variables recorded by the Cancer Department, Center for Non-Communicable Diseases Management, the Ministry of Health and Medical Education and the care system for non-communicable disease risk factors according to province and gender in 2009. Data was analyzed using the ArcGIS 10.3 software and spatial correlation analysis, hot spots analysis, and geographic weighted regression model.
 
Results: The spatial relationship between the disease and some of its risk factors was confirmed by the model of geographical weight regression, according to which the northern and central provinces had the highest risk of colorectal cancer compared to other regions of the country.
 
Conclusion: The results of this study showed that spatial analysis could be useful in identifying disease patterns, prioritizing the factors affecting it, and controlling the disease through strategic planning and interventions.

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Background and Objectives: The incidence of rectal cancer is increasing in developing societies, especially in younger age groups. The aim of this study was to evaluate the factors affecting the survival of patients with rectal cancer in the presence of competing risks.
 
Methods: In this retrospective cohort study, the data of 121 patients with rectal cancer during 2001-2017 were studied. Death related to cancer progression was considered as the interest outcome and other causes of death were considered as competing risks. Cause-specific and sub-distribution hazard models were used to investigate the factors affecting patient survival in the presence of competing risk.
 
Results: The mean (SD) age of the patients was 53.4 (13.9) years and 68 patients (56.2%) were male. The results of log-rank test showed that sex, age, metastasis, type of first treatment, rate of penetration into intestinal wall, tumor location, number of lymphomas involved and tumor size had significant effects on the patient survival (P<0.05). Based on cause-specific and sub-distribution hazard models, tumor stage, lymph node metastasis, and tumor grade had significant effects on death hazard due to the cancer progression (P<0.05).
 
Conclusion: Due to the need to consider competing risks, the results of both competing risk methods showed that tumor grade, lymph node metastasis and stage increased the instantaneous hazard and hazard of cancer death. Therefore, to determine the specific risk factors for each cause of death in the survival analysis, competing risk methods should be used if there is more than one cause of death.

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