Identification of the cells responsible for colon cancer relapse

Colon cancer is the third most common cancer in the world, with about 2 million new cases each year. Most patients are diagnosed when the tumour is still located in the colon or rectum. These tumours are removed by surgery and, in many cases, are treated with chemotherapy in an attempt to prevent relapse. However, for between 20% and 35% of patients, the cancer reappears in the form of metastases in other vital organs. These are caused by residual tumour cells that remain hidden at the time of surgery. Metastases are the leading cause of death from almost all types of cancer, including colon cancer.

Most colorectal cancer research has focused on the primary disease. In recent years, there have also been important advances in the characterisation of metastatic disease once it manifests. However, until now, it had not been possible to study this small population of disseminated tumour cells that is invisible to the diagnostic techniques used in the clinic. This lack of knowledge has resulted in a dearth of effective therapies to eliminate residual disease and prevent metastatic recurrence, which has a poor prognosis. Scientists at IRB Barcelona, led by Dr. Eduard Batlle, ICREA researcher and group leader within the cancer CIBER network (CIBERONC), have for the first time identified residual tumour cells hidden in the liver and lung and have described how they evolve to give rise to the appearance of metastases in these organs.

“Understanding and avoiding the phenomenon of relapse after surgery is an unresolved medical need. After many years investigating colon cancer, we have taken the first step to prevent metastases in patients who present with localised disease,” explains Dr. Eduard Batlle, head of the Colorectal Cancer Laboratory at IRB Barcelona.

How does colon cancer recurrence occur?

Scientists have developed a new experimental mouse model that recreates the process undergone by patients who relapse. This typically goes through the stages of diagnosis, curative surgery, and subsequent relapse. In parallel, they have devised a technique that allows the isolation of the tiny fraction of disseminated tumour cells that are hidden in the liver.

“The model, which is very similar to the progression of metastatic colon cancer in patients, has allowed us to describe the dynamics of residual disease in detail. We have studied metastases ranging from the micro-scale of 3 or 4 cells to medium-sized or even larger ones and have detailed how each of them evolves during the progression of the disease,” comments Dr. Adrià Cañellas-Socias, a researcher at the laboratory headed by Dr. Batlle and first author of the study.

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