A blood RNA test predicts whether residual tumor cells remain in early-stage colon cancer patients and obviates unnecessary surgery. The joint finding by the UPV/EHU and an international interdisciplinary group has made it to the cover and an editorial in the prestigious Gastroenterology journal, one of the most important journals worldwide in the specialty.
Colorectal cancer is the second cause of death related to this tumor disease worldwide. It is the third most common cancer in men and the second most common in women, and early detection can lead to a decrease in incidence and mortality rates. Screening methods are particularly important in this type of cancer, in which the onset of symptoms and signs are associated with advanced stages of the disease.
There are pre-existing lesions, such as polyps, that can be detected to prevent colon cancer from developing. If we remove these polyps, we prevent colon cancer from developing. If we can manage to diagnose this cancer at very early stages, we will also be able to cure it without any kind of treatment."
Luis Bujanda-Fernández de Piérola, Professor of Medicine, UPV/EHU
To this end, "Osakidetza [the Basque Public Health Service] has an early detection programme for colorectal cancer. Its aim is to spot lesions and cancer at an early stage in order to increase the likelihood of cure. It is based on a test that detects tiny amounts of blood in the stool, which apparently are not visible. If the result is positive, a colonoscopy is performed to detect and even cure the disease by removing the cancer through colonoscopy," said Bujanda. However, "there are some inconclusive cases in which we are not very sure whether endoscopy alone can eliminate the disease; in these cases, surgery is usually performed to eliminate any residual cancer cells in the colon wall or lymph nodes," added the UPV/EHU professor.
"This work, which has made it to the cover and an editorial in the prestigious journal Gastroenterology, has involved the development of a non-invasive tool, a simple blood test, to obviate unnecessary surgery," said the author of the paper. "The presence of five microRNAs in the blood has been found to correlate very directly with the presence or absence of cancer cells in the lymph nodes or in the colon wall. That way we are able to obviate unnecessary surgery in colon cancer patients," stressed Luis Bujanda.
"Until now," said Bujanda, "we have relied solely on endoscopy and histological analysis of the removed malignant polyp to determine whether or not to operate on the patient, and the reliability of this is low. Residual tumor cells are found in only 20 % of patients with poor prognosis criteria, according to their surgically removed specimens, so in these cases, 80 % of surgical procedures could be avoided through this analysis. Reliability is significantly increased through this new technique, and almost 90 % certainty is offered in predicting the risk of residual tumor cells remaining in the patient's body. Consequently, this novel technique gives us the certainty of knowing whether or not the patient is going to be operated on. Previous work has also shown very promising results in patients with rectal cancer who are treated with chemotherapy and radiotherapy in advance of surgery to see if there are residual cells before surgery. Operations that have a high impact on patients' quality of life are thus obviated."
This was a joint research project in which the UPV/EHU participated together with researchers from the United States and Japan and the Hospital Clínico of Barcelona. "This is a significant finding verified in a sample of 188 patients with endoscopically removed colon cancer. Right now, the next step would be for other research groups to obtain the same results, validate the findings and for hospitals to incorporate them," said Luis Bujanda.
Wada, Y., et al. (2021) A Liquid Biopsy Assay for Noninvasive Identification of Lymph Node Metastases in T1 Colorectal Cancer. Gastroenterology. doi.org/10.1053/j.gastro.2021.03.062.