Metastases kill more than the original tumor. But what are these metastases due to? To answer this question, researchers in immunology and cancerology at the National Institute for Health and Medical Research (Inserm) and the Universities Descartes and Pierre-et-Marie-Curie (Paris) looked at the mechanisms which determine the ability of cancer cells to migrate around the body and colonize new organs. They then analyzed the environment of tumor cells, made up of support cells (fibroblasts), blood and lymphatic vessels and cells of the immune system, which ensure the body’s defense. The researchers analyzed the genome and environment of tumor cells in 838 patients with Colon Cancer. For 662 people, it was localized cancer. For the remaining 176, the cancer had metastasized.
Their results, published in the journal Science Translational Medicine, show that the genes of cancer cells poorly predict the risk of metastases but that the number of lymphatic vessels and cells of the immune system around the tumor are good predictors of cancer progression. Indeed, “the density of lymphatic vessels is significantly lower in the environment of tumors that have given rise to metastases than in that of localized tumors“explains Inserm in a press release. Same observation for immune cells, which are present in smaller quantities and with less functionality around metastasized tumors.
Prevent the risk of metastasis with immunotherapy
To find out whether these structural and cellular characteristics were the cause of the metastasis or its consequence, the researchers then focused their study on patients showing either precursor signs of metastasis or a tumor located before metastasis. And they found the same lymphatic and immune characteristics, which proves that these two criteria can be causes of metastases. The advantage: using them to predict and therefore prevent these changes. “These two independent parameters are therefore early markers of the metastatic potential of a tumor, and their combined analysis could strengthen the accuracy of the prediction.“thus reveals Inserm. Better still, this discovery could give a new utility to therapies which boost the immune system, such as immunotherapiesthat stimulate the activity of T lymphocytes, a class of cells in the immune system. “Immunotherapies aimed at enhancing the response of T lymphocytes improve the survival of patients who have already metastasized. Our results show that they could also benefit patients with localized tumors but having a weak immune response, therefore likely to develop metastases.“, explains Jérôme Galon, Inserm research director and co-author of this study. New avenues of study for researchers, and new hopes for the 355,000 new people with cancer each year in France.
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