Scientists at the Spanish National Cancer Research Centre (CNIO) have developed a genomic test that can predict whether patients with cancer will respond to chemotherapy. This test identifies specific biomarkers in the genetic profile of tumors, allowing oncologists to determine which chemotherapy drugs are likely to be ineffective. By predicting resistance to treatment, the test aims to help avoid unnecessary side effects and enable more personalized and effective cancer care. The test has shown potential in predicting responses for several common chemotherapy types and various cancers, including ovarian, breast, prostate, and sarcoma tumors. Up to 50% of patients currently do not respond to chemotherapy, making this development significant for improving treatment outcomes and reducing long-term adverse effects.