Alternative for the Cox regression model: using parametric models to analyze the survival of cancer patients

Although the Cox proportional hazard regression is the most popular model for analyzing the prognostic factors on survival of cancer patients, under certain circumstances, parametric models estimate the parameter more efficiently than the Cox model. The aim of this study was to compare the Cox regression model with parametric models in patients with gastric cancer who registered at Taleghani hospital, Tehran, Iran. In a retrospective cohort study, 746 patients with gastric cancer were studied from February 2003 through January 2007. Gender, age at diagnosis, distant metastasis, extent of wall penetration, tumor size, histology type, tumor grade, lymph node metastasis and pathologic stage were selected as prognosis, and entered to the models. Lognormal, Exponential, Gompertz, Weibull, Loglogistic and Gamma regression were performed as parametric models, and Akaike Information Criterion [AIC] were used to compare the efficiency of the models. Based on AIC, Log logistic is an efficient model. Log logistic analysis indicated that wall penetration and presence of pathologic distant metastasis were potential risks for death in full and final model analyses. In the multivariate analysis, all the parametric models fit better than Cox with respect to AIC; and the log logistic regression was the best model among them. Therefore, when the proportional hazard assumption does not hold, these models could be used as an alternative and could lead to acceptable conclusions

Family history as a risk for upper gastrointestinal tract cancer: a case control study

Although, family history of cancer is an important risk factor for upper gastrointestinal cancers development, but limited information is available on the upper gastrointestinal cancers associated with family history in Iran. The purpose of this study was to define upper gastrointestinal cancers risk associated with family history of cancer. This study was conducted as a case control study. A total number of 1,010 cases of upper gastrointestinal cancer and 1,010 healthy controls were recruited. For family history of cancer, questions were asked about any malignant tumor in first and second degree relatives. Adjusted odds ratio estimates for the association family history and upper gastrointestinal cancers risk and corresponding 95% confidence intervals were obtained. A family history of any malignant tumor in relatives was associated with 1.3 fold increased risks of upper gastrointestinal cancers. A first-degree family history of esophageal and gastric cancer was significantly associated with upper gastrointestinal cancers development, with an adjusted OR of 4.7 [CI 95%: 2.6-8.4]. Our findings suggested that risk for upper gastrointestinal cancers increases among individuals with family history of cancer. Therefore, appropriate screening strategies especially in relatives of patients should be considered to prevent and control of disease

Epidemiological differences between colon cancer and rectum cancer

Clinical and epidemiological variation was seen between the colon cancer [CC] and rectum cancer [RC]. So, there is not so much data available about the epidemiological and clinicopathological differences and prognostic factors regarding to CC and CR in Iran, we aimed to perform this study. All cases of CC and RC referred to oncology and gastroenterology wards of Taleghani General Hospital, Teheran, Iran between 2002 and 2008 were retrospectively reviewed. The research group were reviewed all medical records in the study period for collecting the required data. All patients under study were followed up until end day of 2008 [closed day] from their diagnosis. There are 856 cases of CC and 427 cases of RC. Mean survival time of CC cases was relatively higher than RC cases [P <0.05]. Regarding to the age at diagnosis, about 42% of CC and 42.6% of RC patients was diagnosed less than 50 years of age. Positive family history of any cancer was relatively higher in CC [40.0%] patients than RC [31.0%] patients [P<0.05]. significant difference was seen between CC and RC regarding to depth of tumor invasion, pathologic stage and type of first treatment. RC patient were diagnosed in more advanced pathologic stages. Regarding to histology type of tumor 75.0% of CC cases and 79.4% of RC cases was adenocarcinoma. Abdominal pain [74.4%] and blood per rectum [89.7%] were the most prevalent symptoms mentioned by patients for CC and RC, respectively. Distant metastasis, lymph node metastasis, lower BMI and poor grading of tumor was related to increased risk of death due to CC. Regarding to RC, only pathologic stage was determine as prognostic factor. Results of this study emphasis that RC has a poorer prognosis comparing to CC. Up to 42 percent of patients with CC and RC are lower than 50 years of age. Patterns of CC versus RC indicate major variations in demographic and clinicopathologic characteristics that suggest possible differences in etiology and pathogenesis. So we suggest that for the analysis of cancer data, CC and RC should be investigated as separate cancers and not to be as colorectal cancer. Abdominal pain and blood per rectum should be emphasis for detection of CC and RC, respectively

Clinicopathological features of gastric cancer: a study based on cancer registry data

To analysis the epidemiological and clinopathological aspects of gastric cancer. We retrospectively studied the characteristics of 752 gastric carcinoma patients registered in cancer registry center of Taleghani hospital from 2001 to 2006. All the patients confirmed gastric cancer histopathologically. Univariate methods [Mann-Whitney U-test, and chi-square] were used for analysis. Among 752 cases, 535 [71.1%] were male. Sex ratio [male: female] was 2.49:1. The mean age of the patients was 59.7 years [SD = 12.9] at the time of the diagnosis. Weight loss, as a frequent symptom at the time of diagnosis, was observed in 57.7% of the cases. Most of the patients were diagnosed with advanced pathologic stage. In addition, tumor grading was poorly differentiated in most cases [28.7%]; and in 49.9% of the patients, the tumors were located in the stomach, NOS; and distant metastasis was observed in 24.6% of the cases. Based on the results, earlier detection in younger ages and in primary stages of tumor, and subsequent higher quality care to cure GC and increase patients' life expectancy are recommended

Pathology and prognosis of colorectal cancer

Colorectal cancer [CRC] is one of the most common cancers in the world. During the past decades, survival of colorectal cancer patients has improved worldwide, however, it is not clear what factors have contributed to this development. This study was designed to evaluate the prognostic impact of a wide spectrum of pathologic parameters on survival rate in patients with colorectal cancer. 1127 patients with colorectal cancer who registered in one cancer registry in Iran were followed from their diagnostic date to Jan 1, 2007 [as failure time]. Overall survival time was calculated by Kaplan-Meier method. The Cox proportional hazard model was used to identify the pathologic factors that could independently influence survival. The overall survival rate at 5 years after diagnosis was 61%. Histology grade, status of regional lymph node metastasis, distant metastasis and pathologic tumor stage were related to survival rate according to univariate analysis. Nevertheless, in multivariate analysis, only histology grade, distant metastasis and tumor size had influence on survival of colorectal cancer patients. Generally the prognosis of disease is not poor; however, distant metastasis, poor differentiation and higher tumor size should be considered to have additional risks of death in colorectal cancer

Association between polymorphism of MTHFR gene and non-familial colorectal cancer

Colorectal cancer is one of the most common malignancies in worldwide. Because the gene 5, 10-methylene-tetrahydrofolate reductase [MTHFR] plays a key role in methylation, synthesis and repair of DNA, numerous studies have focused on evaluating the correlation between polymorphisms of this gene and sporadic colorectal cancer. This study was carried out to examine the association of MTHFR gene polymorphism, C677T, with non-familial colorectal cancer in an Iranian population. We analyzed peripheral blood samples of 118 cases of colorectal cancer and 189 controls by pyrosequencing method. Controls were subjects who had been referred to our center during the study period and had revealed normal findings on colonoscopy. We found that frequency of CC, CT and TT genotypes among the colorectal cancer patients were 51.7%, 28% and 20.3% respectively. The figures for controls were 47.1%, 27% and 25.9% respectively. Furthermore, allele frequency T in the cases was 34% and allele frequency C was 66% while allele frequency T in controls was 39% and allele frequency C was 61%. Interestingly we observed a reverse association between risk of colon cancer with 677TT genotype

Estimation of survival and factors related to it in Esophageal Cancer using actuarial life-table mathod

Esophageal cancer is the 6th common cancer in Iran. Affected patients have a relatively short lifetime, as this cancer is usually diagnosed in advanced stages. This study was conducted to estimate survival and factors related to it in patients with esophageal cancer. All patients definitely diagnosed as esophageal cancer, registered in Fars Cancer Registry Center, were investigated. Required information was gathered from cancer registry forms and other resources. 1- to 5-year survival rates were estimated using life-table method. Wilcoxon test was used to compare survival rates between subgroups. All data were analyzed by SPSS software. Of 161cases, 61.5% were male. Mean age of patients was 64.6 +/- 13.10 years and 57.6 +/- 11.9 years in male and female, respectively. Overall survival rates at 1- to 5-years after diagnosis were: 58, 33, 18, 15 and 9 percent, respectively. Factors such as age at time of diagnosis, Presence of metastasis, histologic grade, type of first treatment, occupation in males, ethnicity and number of household showed to have a significant effect on prognosis. According to this study and similar studies carried out, screening and early detection of patients [in lower ages, and lower stages] is emphasized