Abstract 5322: BMI and esophageal adenocarcinoma survival

Abstract

Abstract Purpose: Though BMI is a known risk factor for esophageal adenocarcinoma (EA), the effect of BMI on EA overall survival remains unclear. Procedures: The source population is the Esophageal Cancer Study, an ongoing case-control and survivorship study of esophageal cancer patients recruited from Massachusets General Hospital and Dana-Farber Cancer Institute. In September of 2004, the study introduced a new patient questionnaire that included questions on weight throughout adulthood. For this study, we restricted our analysis to Caucasian, male patients with histologically confirmed EA who received their initial diagnosis between 9/1/2004 and 12/31/2014, and who were older than age 40 at time of diagnosis (281 patients). Our exposures of interests were BMI categories (<18.5, 18.5-24.99, 25-29.99, >30) and ΔBMI (the average BMI past the age of 40 minus BMI at time of diagnosis), categorized the differences into <0 (people who gained weight, 0-2 (people who lost some weight), >2 (people who lost substantial weight). We used an extended Cox proportional hazards model to obtain hazard ratios (HR) of BMI at diagnosis and ΔBMI, stratifying baseline hazard by cancer stage, having surgery as a time dependent covariate, and adjusting for radiation and chemotherapy treatment, age, sustained inability to eat solid foods after diagnosis, and smoking status. Results: Of the 282 patients that met our eligibility criteria, 211 men with complete information available were included in the analyses, and there were 131 recorded events during follow-up. In this study population, mean age at diagnosis was 63.7 years (SD±9.8), median survival was 2.6 years, mean average BMI after 40 years of age was 29.0 kg/m2(SD±4.5), and mean BMI at diagnosis was 27.4 kg/m2(SD±4.4). Compared to obese subjects at diagnosis, underweight, healthy weight, and overweight at diagnosis respectively had an adjusted hazard ratios of death (HR) of 2.72(95% CI: 0.59-12.45), 1.79 (95%, CI: 1.06-3.02) and 1.08 (95% CI: 0.65-1.74) (BMI category p=0.04), likely demonstrating reverse causation. Adjusting for confounders, the ΔBMI model shows that patients who lost substantial weight by diagnosis had the highest hazard of death, compared to patients who gained weight in late life prior to diagnosis (HR=0.70, 95% CI: 0.45-1.1) and patients who lost some weight (HR=0.55, 95% CI: 0.35-0.9)( ΔBMI category p=0.05). The strong effect of ΔBMI even after adjusting for patients’ inability or lack of desire to eat (anorexia), implicates cachexia as a possible independent mechanism of this association. In addition, age at dx, stage at diagnosis, and surgical resection were significant predictors of overall survival. Conclusion: Substantial change in BMI prior to diagnosis indicates poor overall survival in middle-aged and elderly Caucasian men with esophageal adenocarcinoma. Citation Format: Elizabeth A. Loehrer, David Christiani. BMI and esophageal adenocarcinoma survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5322. doi:10.1158/1538-7445.AM2017-5322