PTH-296 Validation of nomogram to calculate disease free survival in colon cancer in uk population

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Introduction Currently, the Dukes and AJCC TNM staging systems are widely used to predict survival from colon cancer and assist with clinical decision making. The Memorial Sloan Kettering cancer Centre (MSKCC) nomogram has been developed as an adjunct to these, to predict the five and ten year recurrence free survival probability for patients who had curative resection for colon cancer. The aim of this study is to externally validate the MSKCC nomogram in the UK population, and determine its usefulness. Method The colon cancer database from a district general hospital in England was used to extract all patients who had a curative colon cancer resection. Inclusion criteria were all patients who had curative elective colon cancer resection over a five year period. Patients included in the study were followed up for up to ten years. Variables required for the nomogram were: age, sex, tumour location, CEA levels, T stage, positive lymph nodes, negative lymph nodes, tumour differentiation, lymphovascular invasion, perineural invasion and whether post-operative chemotherapy was given. Five and ten year predictions were calculated for each patient, and plotted against the actual recurrence using a Receiver Operator Characteristic (ROC) curve, and Area Under the Curve (AUC) was calculated for both the five and ten year nomogram. Two cut off points were identified for each nomogram, and this helped to stratify our cohort into three risk groups depending on risk of recurrence. Results 138 patients were included in the study. 49.2% were males with mean age of 69.47 years (SD= 10.81). Overall five year recurrence rate was 26.8% with a mean follow up of 60.24 months (SD= 38.6). 118 patients were included in the five year nomogram validation, and 102 patients were included in the ten year nomogram validation. A ROC curve was plotted for both the five and ten year nomogram and AUC was calculated. For the five year nomogram AUC was 0.673, and for the ten year nomogram AUC was 0.687. Two cut off points were identified for each nomogram and this allowed the groups to be stratified into low, medium and high risk for recurrence. Cox regression showed a significant difference between all groups for both nomograms. Conclusion The MSKCC colon cancer nomogram was validated in our cohort, but is recommended to be used in conjunction with AJCC TNM staging system. The use of risk groups to stratify patients may allow the nomogram to be used simply and effectively in clinical practice. Disclosure of interest None Declared.