And A simple blood test Very effective in Detection of colorectal cancer, One of the most common tumors (a medical term for cancer) in the West and the second cause of death in the population. Its sensitivity is the same as that of fecal occult blood tests. And not only that: it detects tumors early. Doctors believe that liquid biopsy could increase population participation in these examinations, which is currently low participation.
A team of researchers from Hospital del Mar in Barcelona confirmed the usefulness of a liquid blood biopsy to detect tumor markers for this disease. The work has just been published in the journal Annals of Oncology. The results were presented at the recent European Society for Medical Oncology (ESMO) Congress.
Colon cancer screening (in Catalonia it targets men and women between 50 and 69 years of age and consists of detecting small amounts of blood invisible to the naked eye in the stool) significantly reduces the mortality rate from colorectal cancer. However, participation in these offers is “low”. In Barcelona, for example, it does not exceed 50%.
Doctors believe people are not participating because these tests involve “handling faeces”, which carries a “social stigma”. “That is why there has been talk for some time about finding a biomarker that can be obtained through a blood test to enhance this screening,” explains Xavier Bessa, Head of the Gastroenterology Service and Coordinator of the Translational Research Group for Colorectal Tumors. From Del Mar Hospital.
Also in the United States
This is how the researchers thought about this “pilot test” of doing the liquid biopsy, which consists of doing blood tests and seeing if there is circulating tumor DNA. “The goal was to analyze the tumor in a simple blood sample,” explains Dr. Bessa, who also explains that this is the “first time” that liquid biopsy has been used in colorectal screening patients. In addition, in the USA the same test is being performed on thousands of people and the results were “the same” as those obtained in March.
What are these results? According to Dr. Bessa, the hospital's study, which included a group of MAR colorectal screening patients and another group of patients with the disease, shows that the blood biopsy has a sensitivity of up to 90%, much like stool blood tests.
In addition, the study also demonstrated that liquid biopsy detects “pre-tumors.” “For pre-neoplastic conditions, such as colorectal polyps, the sensitivity was only 14%, but the technique was improved by including proteomic analysis and the sensitivity rose to 23% in advanced polyps,” adds this doctor, who believes that the real value lies. Liquid blood biopsy in that it can increase participation in these examinations.
This test, Besa insists, is “experimental” and there is still “a very long way to go” before it is implemented in hospitals. “We won't replace stool blood tests yet, but we are opening the way,” he explains. According to him, it is an “easy” technology to obtain, but at a “higher” cost than the fecal occult blood test. “For the first time we have shown that a blood sample can be useful in detecting colorectal cancer.”
The study analyzed 623 blood samples, 318 of which were from people who underwent colonoscopy between 2017 and 2018 at Hospital Del Mar after the result of a fecal occult blood test, the test used in the colon cancer screening program, came back positive. The remainder were people diagnosed with colon cancer.
The test looks for DNA from the tumor located in the colon, using different strategies simultaneously: it analyzes the presence of DNA mutations, methylations, as well as fragmentations, that is, changes related to the tumor, expanding the range of possible markers.
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