Measuring iron concentration in the gut lavage fluid is helpful for detecting colon cancer

Background and aim: FOBT is helpful to detect advance colon cancer and reduce cancer death. However, FOBT has reported to have high false-positive rate and high false-negative rate. To improve those problems, we developed a new test looking for iron concentration ([Fe]) not in the stool but in the gut lavage fluid (LF) which used to be easily obtained during colonoscopy preparation procedures. Since neoplasm tissue has been reported to show a larger amount of Fe, LF may have high [Fe]. To elucidate this possibility, we investigated relations between endoscopic findings and [Fe] in LF. Method: LF from 150 patients who were FOBT positive and received colonoscopy at Tsukuba University Hospital were investigated. LF were collected at rectum through vacuum vent of endoscope. [Fe] of each sample was determined by colorimetric method and also measured with a specially designed ion-selective membrane electrode. We compared each Fe concentration of the sample with the finding of endoscopic examinations. Result: 21 samples of 150 were excluded such as ulcerative colitis. 129 samples were investigated. We detected 13 cancer, 93 polyp and 24 no finding. The [Fe] in the LF of cancer patients were significantly higher than those in patients with polyp and no finding. Conclusion: The analysis of [Fe] in the gut lavage fluid was demonstrated to be a clue to accurate screening for colon cancer.