Smartphone-Based Rapid Hemoglobin Test Accurately Detects Colorectal Cancer

Despite the availability of colorectal cancer screening programs, participation remains low, especially for fecal immunochemical tests (FIT), a non-invasive method to detect hidden blood in the stool. With only about 20% of the eligible population regularly using FIT, researchers are exploring digital alternatives to improve uptake. Now, a new smartphone-based stool test could serve as a more convenient and patient-friendly option, potentially increasing participation in early detection efforts.

Scientists at the German Cancer Research Center (DKFZ, Heidelberg, Germany) sought to evaluate whether smartphone-based testing could meaningfully supplement traditional laboratory-based FIT screening. Their goal was to leverage everyday technology to reduce barriers and enhance accessibility for individuals hesitant to undergo standard screening procedures. The new method uses a commercially available rapid hemoglobin test paired with a smartphone app.

The process is simple: users collect a stool sample at home using a test stick, mix it in a solution, and place three drops on a test cassette. After a 15-minute wait, the test cassette is photographed using a smartphone. The app then analyzes the color intensity on the cassette to determine the presence of blood in the stool, displaying results instantly. Unlike traditional FIT, this approach eliminates the need for doctor visits, laboratory processing, and long wait times, offering a seamless, private, and immediate at-home experience.

To evaluate the effectiveness and acceptance of the smartphone test, researchers offered it to participants in the BLITZ study, who were already scheduled for colonoscopy appointments across gastroenterology practices in southern Germany between 2021 and 2023. Out of 654 participants, 361 (55%) chose to take the smartphone-based test in addition to the standard FIT. The results were promising: 89% of those who used the smartphone method rated it as a useful alternative to the conventional test, according to a standardized questionnaire.

A comparison with the colonoscopy findings showed that advanced, potentially cancerous mucosal changes were detected by the app in 28% of cases. A comparable sensitivity of 34% was determined for laboratory testing. The specificity—the second important criterion for the informative value of a diagnostic test—was 92% for both methods, suggesting a low rate of false-positive test results. This study suggests that digital tools like smartphone-based stool testing could help overcome longstanding participation barriers in colorectal cancer screening efforts. By making FIT more accessible and user-friendly, such innovations may improve early detection rates and reduce mortality associated with the disease.

“Based on our results, smartphone-based FIT testing could be a meaningful alternative or supplement to traditional laboratory tests,” said co-author Herrmann Brenner. “I see a realistic chance that this additional option will enable us to get more people on board to participate in early colon cancer detection and take advantage of the associated opportunities for colon cancer prevention.”