Abstract
Prostaglandin E2 and cyclic nucleotide levels were measured in plasma and urine of 14 patients with colonic cancer. The measurements were performed 1 day before and 8 days after the removal of the tumor by operation. There was no difference between the plasma PGE2 levels (in form of the 13, 14-dihydro-15-keto metabolite) before and after the operation, but they were significantly higher than the level of a control group. No differences before and after operation were found between plasma cyclic AMP (cAMP) levels, plasma cyclic GMP (cGMP) levels, urinary cAMP levels and urinary cGMP levels. All the cyclic nucleotide concentrations were within the normal range. No correlation could be found between the stage of the tumor spread and any of the substances analyzed. The conclusions are that plasma PGE2 and plasma and urinary cyclic nucleotides do not originate from the colonic tumor tissue, and that these substances cannot be used as tumor markers.