Association of body mass index (BMI) with progression-free survival (PFS) in patients with advanced renal cell cancer (RCC) treated with targeted therapies.

Abstract

e15103 Background: Obesity is strongly associated with an increased risk of RCC. Patients with higher BMI have improved outcomes with nephrectomy. No data exists evaluating the impact of BMI on (PFS) after targeted therapy (TT) for advanced RCC. The majority of targeted drugs are administered in a uniform dose as the initial pharmacokinetics studies did not observe differences based on weight. We investigated whether BMI is associated with (PFS) in advanced RCC. Methods: Using our existing RCC database, we retrospectively identified 141 patients from Jan 2004 to December 2010 who were treated with sorafenib, sunitinib, pazopanib, bevacizumab, temsirolimus or everolimus. This equated to 261 TT courses.Of these, 46 data sets were excluded either for lack of followup or BMI data. BMI was calculated at the start of each therapy and classified into three groups- less than 25 kg/m2, 25 to 30 kg/m2 and greater than 30 kg/m2. PFS was defined as the number of days from treatment initiation to the date of relapse on a treatment. A Cox proportional hazards regression model for multiple events per patient was used to study the increase in hazard ratio between the BMI groups after adjusting for age, gender and treatment regimens Results: In all, 120 patients who received 215 treatment courses were evaluated. The majority was male (79%). The median age was 59 yrs (18-85). The mean KPS was 80. The mean BMI was 27.8 (12.4-52.6); 75 cases had a BMI <25; 79 had a BMI of 25-30, and 60 cases had a BMI >30. Holding age and gender constant, patients who had a BMI of 25-30 had a reduced hazard of progression by 0.58 (p<.0001), which was 42% lower than patients with BMIs <25. Similarly, patients with a BMI >30 had a reduced hazard of progression by 0.39 (p<.0001), which is 61% lower than patients with a BMI <25. Conclusions: Increased BMI was associated with a lower hazard of relapse among patients independent of age, gender and treatment received. To our knowledge this is the first report to show the association of increased BMI with prolonged PFS after targeted therapy in RCC. These findings require validation in larger datasets.