Predicting the risk of gastrointestinal (GI) toxicity in early colon cancer (CC) patients (pts) treated with adjuvant chemotherapy: Developing a GI toxicity scoring system.

Abstract

420 Background: Baseline demographics and clinical factors may contribute to a pt’s overall risk for developing chemotherapy-related GI toxicity, such as nausea, vomiting, and diarrhea. We aimed to develop a GI toxicity scoring system to better stratify early CC pts who may be at higher risk of developing GI toxicity from adjuvant FOLFOX chemotherapy. Methods: Pts diagnosed with early CC from 2005 to 2008 and treated with FOLFOX at the British Columbia Cancer Agency were reviewed. GI toxicities of interest included (1) nausea/vomiting, (2) diarrhea, and (3) any GI side effects. Baseline variables that were analyzed consisted of age, sex, ECOG, time to adjuvant chemotherapy (TTAC), and laboratory parameters. Stepwise regression was used to develop a multivariate model for each toxicity and a weighted risk scoring system was subsequently devised based on the magnitude of the parameter estimates in the multivariate model. Results: In total, 475 pts were included: median age was 62 years (range 26-89), 16.2% were aged >70 years, and 54.5% were men. The majority (90.1%) was ECOG 0/1. Independent predictors for nausea/vomiting included age >70 years (OR 2.46, 95%CI 1.3-4.8, p=0.011), GFR <50 (OR 1.68, 95% CI 1.1-2.7, p=0.025), and TTAC >8 weeks (OR 1.33, 95% CI 0.9-2.1, p=0.14) whereas independent predictors for diarrhea included age >70 years (OR 1.44, 95% CI 0.79-2.62, p=0.12) and GFR <50 (OR 1.67, 95% CI 1.1-2.6, p=0.018). The multivariate model for the risk of any GI toxicity included age >70 years (OR: 2.61, 95% CI 1.1-6.1, p=0.049), GFR <50 (OR 1.69, 95% CI 1.1-2.6, p=0.0038), and TTAC >8 weeks (OR 1.79, 95% CI 1.2-2.7, p=0.0059). Points were assigned: 2 points for long TTAC and poor GFR and 1 point for advanced age. The study cohort was classified into their risk groups based on their score (Table). Conclusions: We developed a simple 5-point scoring system to stratify early CC pts receiving adjuvant FOLFOX into low and high risk groups for GI toxicity based on baseline clinical factors. Further validation of this scoring system is required. [Table: see text]