We were able to demonstrate for the first time by a statistical method also applied in systems biology that variations in the expression of the growth inhibiting CYP27B1/VDR system relative to tumorigenic COX-2 and CYP24A1 could account for the significant age- and gender-related influence on incidence and malignity of cancers at different anatomical locations within the colorectum, which we had reported previously [2]. The gene discussed is PTGS2; the disease is cancer.