SIRT1 and colorectal carcinoma: In a supplementary analysis, we explored gene-environment (GxE) interactions on multiplicative and additive scales between SIRT1 polymorphisms and metabolic CRC risk factors (body size, physical activity and early life energy restriction) in relation to CRC by MSI and CIMP status as was done for CRC risk overall and by subsite using the 20.3 year follow-up data.