The common symptoms of osteosarcoma include, first, pain which is often persistent, typically occurring at the distal femur, proximal tibia, and proximal humerus. The characteristic of this pain is that it worsens at night, more severe than during the day. Second, there is local swelling usually near joints, particularly at the three aforementioned common sites. The skin over the swelling often becomes warm and may even show redness, and some patients may have dilated surface veins. The swelling can frequently cause dysfunction of nearby joints, or restricted function. Third, systemic symptoms primarily include a persistent wasting syndrome, known as cachexia. Fourth, osteosarcomas can weaken the bone's load-bearing capacity and strength following cortical bone involvement, eventually leading to pathological fractures. Therefore, the main symptoms of osteosarcoma are localized pain, local swellings, systemic manifestations of cachexia, or pathological fractures.