Breast cancer is detectable from peripheral blood using machine learning over T cell receptor repertoires

The immune system's defense abilities rely on the diversity of T and B lymphocytes. T Cell Receptors (TCRs) are generated through V(D)J recombination, where distinct genetic elements combine and undergo modifications, creating extensive variability. In breast cancer, the most frequently diagnosed cancer in women, early detection sometimes helps with highly effective and potentially curative treatment. The TCR repertoire may provide information about tumor status. To test this, we investigated the peripheral blood TCR repertoire and its association with tumor status. We collected blood samples from 98 women, including patients and healthy donors. Following TCR profiling, machine learning of these data was able to show an association between TCR profiles and breast cancer presence or absence with high accuracy (average AUC of 0.96). Our findings imply the immune system retains tumor-relevant, TCR-related, signals detectable in blood. This information could potentially benefit future derivatives from this knowledge, either in the field of detection or treatment.