Predicting cumulative incidence of chemotherapy toxicity in older patients with cancer: Korean Cancer Study Group prospective cohort study (KCSG) PC 13-09.
e21539 Background: Older adults have increased risk of developing chemotherapy toxicity. Currently available prediction tools do not provide information on cumulative risk and none are from Asia. Methods: Patients with histologically confirmed solid cancer aged ≥70 years were prospectively enrolled from 17 centers and underwent geriatric assessment before starting their 1st line chemotherapy. Chemotherapy toxicity prediction model was built for adverse events (AEs) ≥G3, among geriatric assessment, laboratory and clinical variables. Model discrimination values were evaluated using c-statistics compared with actual cumulative incidence of AE ≥G3 in each cycle. Results: 301 patients were enrolled with a median age of 75 years (range 70-93). Primary site included colorectal (28.9%), lung (24.6%), hepato-biliary-pancreatic (22.3%), stomach (10.6%) and others (13.6%). Median chemotherapy cycle was 4 (2-7 cycles). During first line chemotherapy, 53.8% of patients experienced AEs ≥G3. Six variables significantly associated with occurrence of AEs ≥ G3 were serum protein < 6.7 g/dL, no dose reduction at first cycle, suffering from psychological stress or acute disease in the past 3 months, water consumption of less than 3 cups per day, not being able to obey command of 'Grab a piece of paper in your hand', and self-perception of ‘not in good health’. Model with all six variables was selected with the highest mean value of c statistics (0.646) and prediction tool indicated score ranging from 0 to 8 points. Patients were classified to 4 risk groups; 61 (21.0%), 143 (49.3%), 66 (22.8%), and 20 (6.9%) in low (0, 1 point), medium-low (2, 3), medium-high (4, 5), and high risk group (6, 7, 8). Predicted cumulative incidence of AEs ≥G3 was discriminated according to risk groups; low risk group: 13%, 19%, 27%, 30%, 30% in cycle 1, cycle 2, cycle 3, cycle 4, cycle 5, medium-low risk: 17%, 37%, 48%, 56%, 60%, medium-high risk: 26%, 44%, 50%, 68%, 75%, and high risk: 45%, 62%, 87%, 94%, 94%. Conclusions: Novel prediction tool could identify those at high risk of developing AEs ≥G3 after chemotherapy, which provided information on cumulative incidence in each cycle.