Early osteosarcoma. Pain is an early symptom, which can appear before the tumor appears. At first, it was intermittent pain, which gradually turned into persistent severe pain, especially at night. Malignant tumor pain occurs earlier and more seriously, and there is often a history of local trauma. The tumor near the bone end joint is large, with different hardness, tenderness, local high temperature, venous dilatation, sometimes palpable pulsation and pathological fracture. General health gradually declines to failure, and most patients have lung metastasis within one year. Selenium supplementation, such as selenium Weikang chewable tablets, can improve immunity and inhibit the growth, diffusion and metastasis of cancer cells.