PRIMARY OBJECTIVES:~I. To compare the expression of 15-hydroxyprostaglandin dehydrogenase (PGDH) messenger ribonucleic acid (mRNA) and protein levels in tumor tissue at baseline and after treatment with 25-hydroxy (OH)-vitamin D3 (cholecalciferol).~II. To compare the expression of 15-PGDH mRNA and protein levels in normal colorectal mucosa at baseline and following treatment with 25-OH-vitamin D3.~SECONDARY OBJECTIVES:~I. To compare the expression of cyclooxygenase (COX)-1 and COX-2 mRNA in tumor tissues at baseline and after treatment with 25-OH-vitamin D3.~II. To compare levels of prostaglandin E2 (PGE2) in tumor tissue at baseline and after treatment with 25-OH-vitamin D3.~III. To compare the expression of COX-1 and COX-2 mRNA in normal colorectal mucosa at baseline and after treatment with 25-OH-vitamin D3.~IV. To compare levels of PGE2 in normal colorectal mucosa at baseline and after treatment with 25-OH-vitamin D3.~V. To evaluate the tolerability of a single 100,000 international unit (IU) dose of 25-OH-vitamin D3.~OUTLINE:~Patients receive cholecalciferol orally (PO) 7 days prior to scheduled surgery or endorectal ultrasound. Patients are only followed through surgery or endorectal ultrasound. In case of a vitamin-D-related toxicity, the patient will be followed for resolution of the toxicity, up to 6 months.
This pilot clinical trial studies cholecalciferol in treating patients with colorectal cancer. The use of cholecalciferol may slow disease progression in patients with colorectal cancer.