Validating quantitative obesity measurements in colorectal cancer patients.

BACKGROUND: Over 70,000,000 American adults are overweight, and obesity accounts for $147 billion annually in medical expenses. Since measuring obesity by body mass index (BMI) fails to account for fat distribution and quantity, recent work has explored quantitative measures of visceral fat area (VFA) and subcutaneous fat area (SFA) obtained from CT imaging. However, use of CT to quantify adipose tissue has not been evaluated in colorectal cancer (CRC) patients and the optimal anatomic location for measuring VFA and SFA has yet to be determined. We measured VFA and SFA at three different anatomic locations to determine which location was optimal in CRC patients.

METHODS: A database of patients undergoing CRC surgery from 2002 to 2009 was reviewed to identify patients with preoperative CT imaging. Quantitative measurements of both VFA and SFA were calculated at the level of L4-L5, L2-L3, and mid-waist.

RESULTS: A total of 244 colorectal cancer patients had preoperative imaging available and 99% were men. VFA and SFA quantified by CT at the levels of L2-L3, L4-L5, and mid-waist were all significant independent predictors for medical complications of obesity including diabetes (HR 1.04 -1.06) and hypertension (HR 1.04-1.09) on multivariate analysis. The location used for imaging did not affect predictive power. Additionally, waist circumference was also a significant independent predictor of diabetes (HR 1.56) and hypertension (HR 1.70).

CONCLUSIONS: Quantitative measures of obesity from CT imaging in CRC patients correlated significantly with medical conditions known to be associated with obesity. This indicates that direct measurement of adiposity is valid in colorectal cancer patients.