Serum total homocysteine increases with the rapid proliferation rate of tumor cells and decline upon cell death: a potential new tumor marker

Background: We were interested to know why cancer patients are frequently associated with elevated circulating total homocysteine (tHcy) even though they are not treated with anti-folate drugs. Methods: We employed tissue cultures to compare both the homocysteine (Hcy)-released and production of tumor markers between tumor and normal cell lines. Results: We detected much higher concentrations of homocysteine (Hey) released by the tumor cells. However, much less difference was found between normal and tumor cell lines when Hey concentration was expressed per the same number of cells. During the cell culture, the increase of Hey and the increase of tumor marker concentration paralleled each other for the first 7 days. After the seventh day of the culture when cells started dying, tumor markers continued to rise, whereas levels of Hey and cell numbers leveled off. We found that the serum concentration of Hey fluctuated in circulation coinciding with that of tumor marker in individual cancer patients unless taking anti-neoplastic drug. Conclusions: The elevation of tHcy concentration may be caused by the rapid tumor cell proliferation and reflect only the number of live cells. Serum Hey may be a potentially useful tumor marker to monitor tumor activity. (C) 2002 Elsevier Science B.V. All rights reserved.