Prognostic and predictive role of body mass index (BMI) in metastatic colorectal cancer (mCRC): a pooled analisys of tribe and tribe-2 studies by GONO

Background: Obesity is associated with an increased risk of development and recurrence of colorectal cancer. The role of obesity in metastatic colorectal cancer patients (pts) is still unclear, especially in those treated with triplet plus bevacizumab (bev). The aim of our study was to evaluate the prognostic and predictive role of BMI in metastatic colorectal cancer pts treated with FOLFOXIRI plus bev or FOLFIRI/FOLFOX plus bev in the TRIBE and TRIBE-2 trial. Materials and methods: A total of 1160 pts enrolled in TRIBE and TRIBE-2 trials were included. Baseline height and weight were used to assign pts to one of the following BMI categories: underweight (group A = BMI <18.5 kg/m2; 52 pts), normal (group B = BMI 18.5-29.9 kg/m2; 952 pts) and obese (group C > 30 kg/m2; 156 pts). Results: In our population, no differences in terms of PFS (P = .43) or OS (P = .99) resulted between 3 groups. No interaction effect between treatment arm and BMI was evident in terms of PFS (Group A HR: 0.65 [95%CI: 0.36-1.16]; Group B HR: 0.77 [95%CI: 0.67-0.88]; Group C HR: 0.67 [95%CI: 0.48-0.93]; P for interaction = .75) or OS (Group A HR: 0.57 [95%CI: 0.29-1.12]; Group B HR: 0.85 [95%CI: 0.73-0.99];Group C HR: 0.69 [95%CI: 0.48-1.01] P for interaction = .36). No statistically significant difference in terms of dose reductions due to toxicities were found according to BMI in the overall population (P = .48) and in pts treated with FOLFOXIRI plus bev (P = .57). Conclusion: BMI was neither prognostic or predictive for PFS and OS in our population. Our analyses showed that the advantage of FOLFOXIRI plus bev versus FOLFIRI/FOLFOX plus bev was independent from BMI.