The combined RR of leucopenia and thrombocytopenia was 1.21 (95% CI: 1.01, 1.45) and 1.36 (95% CI: 1.06, 1.76), respectively, suggesting that COX-2 inhibitors increased hematologic toxicities (grade ≥ 3) related to chemotherapy. The gene discussed is PTGS2; the disease is Thrombocytopenia.