Researchers report the discovery of the population of residual tumor cells responsible for the recurrence of colorectal cancer in other organs after removal of the primary tumor. The study shows that early immunotherapy, before surgery, can eliminate these cells before they have started to develop a metastasis, and thus prevent relapse of the disease. The work paves the way for the development of new therapeutic approaches and diagnostic tools to slow down the progression of the disease and improve its prognosis.