An individualized conditional survival calculator for patients with rectal cancer

Background: Conditional survival estimates account for time survived since diagnosis to provide prognostic information for long-term cancer survivors. For rectal cancer, stage-related treatment (eg, neoadjuvant radiotherapy) affects pathologic stage and therefore stage-associated survival estimates. Objective: The aim of this study is to estimate conditional survival for patients who have rectal cancer and to develop an interactive calculator to use for individualized patient counseling. Patients: Patients with rectal adenocarcinoma were identified by using the Surveillance Epidemiology and End Results registry (1988-2002, N = 22,610). Design: Cox regression models were developed to determine adjusted survival estimates (years 1-10) and used to calculate 5-year adjusted conditional survival. Models were built separately for no radiotherapy, preoperative radiotherapy, postoperative radiotherapy, and patients with stage IV disease. Covariates included age, sex, race, tumor grade, and type of surgery. An Internet-based conditional survival calculator was developed. Results: Radiotherapy was given to 42.6% of patients (14.1% preoperative, 28.4% postoperative). Significant improvements in 5-year conditional survival were observed for all stages, with the exception of stage I because of the initial high survival probability at diagnosis. Patients with advanced stage had the greatest improvements in conditional survival, with 5-year absolute increases of 33% (stage IIC) and 54% (IV). Other factors associated with conditional survival included sequence of radiotherapy and surgery, age, race, and tumor grade. The Internet-based conditional survival calculator can be accessed at www.mdanderson.org/rectalcalculator. Limitation: The data source used does not include information on chemotherapy treatment, change in staging after neoadjuvant treatment, or patient comorbidities. Conclusion: Conditional survival estimates improve over 5 years in patients who have rectal cancer; the greatest improvements are observed among patients with advanced stage disease. The conditional survival calculator is an individualized decision support tool that informs patients, who must make non-treatment-related life decisions, and their clinicians planning follow-up and surveillance.