PTGS2 and osteosarcoma: The data from 11 comparative studies, including of 495 patients with osteosarcoma vs. 247 benign osteochondroma patients, revealed that COX‐2 expression was significantly more increased in osteosarcoma than in benign osteochondroma (OR = 7.66, 95% CI = 5.25–11.17, P < 0.001) (Fig. 2).