In colorectal carcinoma patients, serum vitamin D levels vary according to stage of the carcinoma

BACKGROUND. Epidemiologic studies have demonstrated an inverse correlation between dietary calcium and vitamin D intake and the incidence of colorectal carcinoma. Elevated serum levels of 25-hydroxyvitamin D₃ (25-OH- D₃) are associated with a major reduction in the incidence of this neoplasm. The reduction in tumor size and number induced by calcium supplements in an experimental carcinogenesis model was neutralized by vitamin D₃ deficiency. To the authors' knowledge, vitamin D serum levels have never been determined previously in colorectal carcinoma patients. They compared serum 1,25- dihydroxyvitamin D₃ (1,25(OH)₂D₃), 25-OH-D₃, and parathyroid hormone (PTH) levels of colorectal carcinoma patients with those of healthy controls. METHODS. Serum 1,25(OH)₂D₃, 25-OH-D₃, and PTH levels were determined in 84 colorectal carcinoma patients (10 with Stage I, 29 with Stage II, 25 with Stage III, and 20 with Stage IV) and 30 healthy controls, all of whom were normocalcemic and not taking calcium or vitamin D supplements. RESULTS. 25- OH-D₃ serum levels were higher in cancer patients than controls, irrespective of stage. Serum 1,25(OH)₂D₃ decreased with advancing stage: 73 ± 18, 48 ± 16, 39 ± 12, 34 ± 13, and 75 ± 20 pg/mL in Stages I, II, III, IV, and controls, respectively. There was a corresponding increase in serum PTH levels: 58.0 ± 9.4, 73.7 ± 14.4, 79.0 ± 21.3, 100.4 ± 30.9, and 51.2 ± 3.9 pg/mL in Stages I, II, III, IV, and controls, respectively. Serum vitamin D metabolite levels did not correlate with gender, age, tumor localization, or histologic grade. CONCLUSIONS. An inverse correlation between serum levels of the active metabolite of vitamin D and colorectal carcinoma stage has been demonstrated for the first time, to the authors' knowledge, in colorectal carcinoma patients. Because 1,25(OH)₂D₃ has been shown to inhibit proliferation of colonic epithelial cells, decreased serum levels may facilitate the growth of colorectal carcinoma and influence its biologic behavior.