PIK3CA and obesity due to melanocortin 4 receptor deficiency: In multivariate analysis adjusted for sex, age, tumor location, tumor size, differentiation status, vascular invasion, TNM stage, KRAS, BRAF and PIK3CA mutations and MSI stutus, the association of disease-free survival with obesity was statistically significant for the adjusted HR was 1.71 (95% CI: 1.10–2.68 P = 0.018).