Changes in small intestine permeability after radiotherapy of malignant tumor

Radiotherapy of the malignancy in the small pelvis causes different adverse events in normal tissues. The small intestine is the most sensitive organ in this region. Its wall performs the barrier function between internal and external environments. The damage to the intestinal barrier brings increase in the intestinal permeability. The aim of this study was to find out dependency of intestinal permeability disorder on certain factors such as age, radiation dose, target volume, dose per fraction, added chemotherapy etc.

We evaluated the intestinal permeability by the LAMA (lactulose-mannitol) test in a group of 31 patients with a diagnosis of malignant gynecological tumor (24), rectal cancer (6) and prostate cancer (1) who underwent radiotherapy of the small pelvis with doses of at lest 45.0Gy. Fourteen patients underwent adjuvant radiotherapy, and 17 patients underwent a primary radical radiotherapy. In the latter group there was a tumor at the time of radiotherapy. The measurement was performed 3x (before starting radiotherapy, after its completion, and 6 months after completion). Complications after radiotherapy were assessed according to RTOG classification. LAMA test resultswere statistically worked out.

Early complications G1, G2 were observed in 22 patients, late complications G1 in 3 patients. No dependency has been proved between grade of complications and intestine permeability changes. No evidence has been found in dependency on the patients' age, target volume, added chemotherapy, size of fraction, energy of radiation or other factors either. Connection of intestine permeability changes and total dose was on the margin of statistical significance; the only statistically significant relation was between intestinal permeability change and presence of tumor in the organism which was very surprising and cannot yet be explained.

More patients should be involved in the study and late postirradiation changes should be assessed at a longer time interval.