Stage iii colon cancer

Vitamin D, which is obtained via diet or by synthesis following exposure to the sun is converted to an intermediate, 25-hydroxyvitamin [D.sub.3] or 25-OH-[D.sub.3], and finally to its active form, 1,25-dihydroxyvitamin [D.sub.3] or 1,25[(OH).sub.2][D.sub.3]. Recent evidence has shown that the active form of vitamin D, 1,25[(OH).sub.2][D.sub.3], has an antiproliferative effect: specifically, there may be an inverse relationship between vitamin D intake and the incidence of colorectal carcinoma.

Since colorectal carcinoma is a leading cause of mortality and morbidity in the Western world, many prevention strategies are being investigated. Screening and early detection of this cancer or its precursors is a very helpful prevention strategy, but a recent study published in Cancer decided to investigate another approach. Yaron Niv and colleagues compared serum 1,25-dihydroxyvitamin [D.sub.3], 25-hydroxyvitamin [D.sub.3], and parathyroid hormone (PTH) levels of colorectal carcinoma patients with those of healthy controls.

Eighty-four colorectal carcinoma patients were recruited from three medical centers in Israel and compared to 30 healthy controls. Serum levels of calcium, 1,25-dihydroxyvitamin [D.sub.3], 25-hydroxyvitamin [D.sub.3], and PTH were measured in all the subjects. Blood samples were taken at the time of diagnosis, before the patients underwent surgery or any other therapy.

Serum 25-OH-[D.sub.3] levels were higher in all colorectal carcinoma groups compared with controls. Plasma concentrations of the active form of vitamin D, 1,25[(OH).sub.2][D.sub.3], were significantly lower in patients with higher stages of the disease (Stages III and IV). PTH levels were inversely related to 1,25[(OH).sub.2][D.sub.3]. There were no significant differences in these results after controlling for gender, age, tumor localization, and tumor grade.

The results indicate that there is an inverse, stage-dependent correlation between the stage of colorectal carcinoma and 1,25[(OH).sub.2][D.sub.3] serum levels in normocalcemic patients. The research team could only explain the higher levels of 25-OH-[D.sub.3] found in cancer patients by stating that the results were not statistically significant. Because blood samples were taken only once during this study, the researchers cannot offer any explanation of the mechanism involved with these results. They do hypothesize that some tumors may secrete a substance that inhibits the synthesis of 1,25[(OH).sub.2][D.sub.3], which may explain the lower levels in patients with advanced colorectal disease. However, more research is needed from clinical trials to confirm this data.

Yaron Niv, Ami D. Sperber, Arie Figer, et al., In Colorectal Carcinoma Patients, Serum Vitamin D Levels Vary According to Stage of the Carcinoma, Cancer, 86: 391-397 (August 1999) [Correspondence: Yaron Niv, MD, Dept. of Gastroenterology, Beilinson Campus, Rabin Medical Center, Petah-Tikvah, Israel.]