Nomogram for Predicting Overall Survival and Salvage Abdominoperineal Resection for Patients with Anal Cancer

Anal cancer treatment has evolved from abdominoperineal resection to chemoradiotherapy, which allows for sphincter preservation. OBJECTIVE: The aim of this study was to develop an accurate model and nomogram to predict overall survival and the probability of salvage abdominoperineal resection for anal cancer patients. DESIGN: This is a retrospective cohort study. SETTINGS: Data were gathered from National Cancer Database entries from 1998 to 2010. PATIENTS: Patients with de novo anal cancer were selected from the National Cancer Database in the years 1998 through 2010; 1778 patients were included, and their data were analyzed. MAIN OUTCOME MEASURES: Variables included time to death, censoring indicator, age, race, sex, tumor size, year of diagnosis, surgery status, nodal status, TNM stage, and chemoradiation therapy. A stratified Cox proportional hazards model for overall survival and a logistic regression model for salvage abdominoperineal resection were developed. Our final models were internally validated for discrimination and validation. RESULTS: Statistically significant variables in the salvage surgery model were tumor size and nodal status (p ≤ 0.001). For overall survival model, statistically significant variables (all with p ≤ 0.005), fitted across the strata of TNM clinical stage included age, sex, tumor size, nodal status, chemoradiotherapy treatment, and combination salvage surgery and chemoradiotherapy. Nomograms that predict events are based on our final models. LIMITATIONS: Limitations included clerical database errors and nonmeasured variables, such as HIV status. CONCLUSIONS: A nomogram can predict overall survival and salvage surgery for an individual with anal cancer. Such tools may be used as decision support aids to guide therapy and predict whether or not patients may need salvage surgery.