We explored interactions on both additive and multiplicative scales between SIRT1 rs10997870 and rs12778366 genotypes (dominant model), and six metabolic CRC risk factors recoded into a binary fashion for reasons of power (height, adult BMI, trouser/skirt size, BMI at age 20, physical activity, and early life energy restriction using the place of residence during the Dutch Hunger Winter as a proxy variable). The gene discussed is SIRT1; the disease is colorectal carcinoma.