Vitamin D, calcium, and early-onset colorectal neoplasia

Abstract

Colorectal cancer (CRC) incidence among individuals younger than age 50 has been increasing. Although the overall CRC incidence has been decreasing in many parts of the world, early-onset CRC (defined as CRC diagnosed before age 50) has been increasing at an alarming rate. Unlike the traditional CRC that is well-studied and associated with many risk factors, early-onset CRC has not been studied much and has no simple explanation for its causes. In Chapter 1, we examine vitamin D intake in relation to early-onset CRC. Vitamin D has consistently been studied with CRC risk. In addition, the recent increase in early-onset CRC incidence temporally overlaps with vitamin D deficiency around the world. Thus, we hypothesized that vitamin D could be related to early-onset CRC risk. In Chapter 2, we assess vitamin D intake in relation to early-onset conventional adenoma and serrated polyp. Conventional adenoma and serrated polyp are precursors to cancer, so studying them help understand about CRC. We therefore evaluated whether vitamin D is associated with early-onset conventional adenoma and/or serrated polyp among those who underwent at least 1 lower endoscopy. In Chapter 3, we evaluate the association between calcium and early-onset CRC. Calcium and vitamin D are often studied together because they are both nutrients essential for bone health. Moreover, in experimental studies, they have been studied to have anti-cancerous properties. The World Cancer Research Fund/American Institute for Cancer Research concluded calcium as having strongly probable evidence of a causal inverse association with CRC risk. However, the association between calcium and early-onset CRC has not been studied before. Therefore, we investigated the association between calcium, dairy foods, and early-onset CRC risk. Our findings suggested that increasing vitamin D and calcium intake could be encouraged for CRC prevention among individuals younger than age 50.