Background: Since population screening has the potential to reduce mortality from rectal cancer (RC), novel methods with improved cost-effectiveness warrant consideration. In a previous pilot study, we found that the rapid, inexpensive and non-invasive electromagnetic detection of RC is a highly specific and sensitive technique. The aim of the present prospective study was to evaluate the prediction accuracy of electromagnetic detection of RC.
Methods: 304 eligible subjects were consecutively enrolled in our Institute and subjected to electromagnetic detection followed by colonoscopy and histopathologic analysis of biopsies. A putative RC carrier status was attributed to subjects showing an electromagnetic signal < 50 units (U).
Results: RC patients showed a significantly lower electromagnetic signal (40.9 +/- 0.9 U; mean +/- S.E.) than did non-RC subjects (79.2 +/- 1.4 U; P < 2.2e-16). At a threshold < 50 U, electromagnetic detection identified 103 putative patients, whereas colonoscopy detected 108 patients, with an overlap of 91 patients between the two methods. The 15.7% false-negative rate by electromagnetic detection was brought to zero by raising the threshold value to 70 U; on the other hand, such a threshold increased the false-positive rate to 30%.
Conclusion: Electromagnetic detection of RC at a signal threshold < 70 U appears to eliminate false-negative results. Although colonoscopy would still be required in examining the false-positives associated with the < 70 U electromagnetic threshold, the need for this method would be reduced. Thus, electromagnetic detection represents a new accurate, rapid, simple, and inexpensive tool for early detection of RC that merits testing in large population-based programs.