Survival Analysis of Colorectal Cancer Patients Using Exponentiated Weibull Distribution

Colorectal cancer is a highly prevalent cancer across the world, which is associated with significant mortality. Therefore, special attention must be paid to the prevention and care of this fatal disease. The present study aimed to evaluate the effective methods to prolong the survival of colorectal cancer patients and determine the influential factors in their longevity using the exponentiated Weibull statistical model.
Medical records of 446 colorectal cancer patients referring to Taleghani Hospital in Tehran, Iran during 1985 - 2013 were reviewed. The exponentiated Weibull model is an extended version of the Weibull model, which is used to investigate the survival of colorectal cancer patients and assess the influential factors in their survival and longevity. We also compared the model with the Weibull-exponential model for better practice.
Mean survival rate of the patients was 4.52 ± 0.182 years. According to the exponentiated Weibull model, age at diagnosis was the only significant influential factor in the survival of colorectal cancer patients (P = 0.002). Other factors such as gender, tumor size, family history of colorectal cancer, tumor site, and body mass index had no significant effects on the survival of these patients. The proposed model was considered superior to the Weibull-exponential model due to the lower Akaike’s information criterion.
According to the results, age of colorectal cancer patients at the time of diagnosis is the most important influential factor in increasing their survival and reducing the mortality rate. Therefore, it is recommended that proper care be provided for the elderly patients with colorectal cancer, especially at the onset of the disease.