Effect of chemotherapy with 5-fluorouracil on intestinal permeability and absorption in patients with advanced colorectal cancer

5-Fluorouracil (5-FU), in association with leucovorin (LV), is the most use d chemotherapy agent in the treatment of colorectal cancer. Response rate, as well as side-effect incidence, increases with the dose intensity of regi mens that are used. The most common dose-limiting toxicity for 5-FU/LV modu lation is diarrhea. To as sess the modification of small intestinal functio n, we investigated the changes in intestinal permeability (IP) and intestin al absorption (IA) in 41 chemo-naive patients (21 men and 22 women; mean ag e, 61 +/- 9 years) with advanced colorectal cancer after treatment with the association of folinic acid and 5-FU. After chemotherapy administration, w e found a marked increase in LP and a reduction in IA, measured as cellobio se-mannitol (CE-MA) ratio (p < 0.0001) and D-xylose absorption (p = 0.0001) , respectively. Patients who experienced diarrhea have an increase in CE-MA ratio and a reduction in D-xylose absorption values, both statistically si gnificant. Cellobiose-mannitol ratio and D-xylose absorption tests can be u sed fur the assessment of toxic effect of 5-FU on mature intestinal epithel ium and also for evaluating the role of cytoprotective agents.