When analyzing patients with high or low levels of circulating B lymphocytes, high levels of CD19+ B lymphocytes associated with metastatic burden (≥3 metastatic sites, p = 0.047) and higher levels of circulating tumor cells (CTCs, ≥5 CTCs at baseline, p = 0.047, Table 1 and Supplementary File S1). The gene discussed is CD19; the disease is neoplasm.