Prognostic factors of survival of patients with oesophageal cancer under radiotherapy using cox regression model

oesophageal cancer is one of the most fatal cancer in human in spite of high incidence in the north of Iran and poor prognosis,there is not information regarding prognostic factors in this area.this study was conducted to determine prognodtic factors of the survival of patients with oesophageal cancer under radiotherapy.We conducted a descriptive-analytical study using historical cohort that has been performed on the bases of information presented in nmedical record of patients with oesophageal cancer referred to the shahid Rajaii radiotherapy cancer in Babilsar from 1992 to 1996.out of 523 patients,we followed 130 patients in nonrandomized convenience sampling based on the availability of the address for corressponding .the data was analysed using survival analysis by nonparametric method of Kaplan Meier and Cox regression model and the risk ratio(RR)nof prognostic factors was determined.the results showed that the suevival rates in  patients with oesophageal cancer were 0.42 in 1 year,0.21 in 2 year,0.11 in 3 years and 0.08 in 65 years after diagnosis.the patients with the age of 50-64 years had poorer survival rate than ones under 50 years of age and the risk ratio in this age group has been significantly in creased (RR=1.73,P=0.01): the risk ratio for patients above 65 years in comparison with patients under 50 years was 1.88(p=0.01).the fameles had better suevival than males significantly (rr=0.71,p=0.02).for each 100 rads dose of radiotherapy,the risk ratio was decreased by 1%(RR=0.99,p=0.05):for each session of radiotherapy,the risk ratio significantly increased (RR=0.96,p=0.0001):for each square centimeter surface area under radiotherapy,the risk ratio significantly increased(RR=1.002,p=0.04).we did not observed a significant difference on survival based of the type of histology,anatomical location,and the type of treatment(p>0.05).although the survival of patients with oeophageal carcinoma has been significantly related to sex,age,radiation dise,frequency of treatment and surface size of radiotherapy,the prognosis is extremely poor.to compare various combined modality of treatment of oesophageal cancer , a more randomized clinical trials with enough sample size is suggested.