Serum phosphohexose isomerase activities in patients with colorectal cancer.

Pretreatment levels of phosphohexose isomerase (PHI) were above the cutoff limit of 107 IU/l in 41% of patients with benign intestinal diseases and in 46% of patients with colorectal cancer. Sensitivity of PHI was related to the presence of distant metastasis and the location of the primary tumor. Patients with rectal tumors presented a lower sensitivity than patients with colonic tumors. Pretreatment levels of PHI had prognostic value and patients with elevated levels of this enzyme showed a shorter disease-free interval in comparison with those patients with normal PHI activities. However, the prognostic significance of PHI was not independent of Dukes' classification. The present study indicates that PHI is not useful in the follow-up of patients with colorectal cancer after curative surgery because of its low sensitivity in the diagnosis of recurrences (47%) and its low specificity in patients without evidence of disease (76%).