However, Koning et al. showed that CXCL8 levels were higher for PR- than PR+ breast cancer (p = 0.033 [71]; p = 0.019 [52]) among patients with no circulating tumor cells (p = 0.017) or grade 3 breast cancer (p = 0.03) [71]. The gene discussed is CXCL8; the disease is breast carcinoma.