For osteosarcoma in its late stages, it often metastasizes to other organs, with the majority of cases involving lung metastasis. In such cases, conservative treatment can be applied. However, if surgery is an option, it is the best approach as it can be complemented with postoperative chemotherapy and radiotherapy to extend the patient’s survival time. If there is distant metastasis and the body is in poor condition, unable to withstand surgery, then only conservative treatment and nutritional support are viable, along with the use of painkillers. In late stages, when the patient cannot tolerate surgery, only conservative treatment is available with no other alternatives. Typically, the conditions are divided into three stages. By stage three, there is usually lung metastasis. This stage often involves T which signifies intracompartmental or extracompartmental growth—T2 indicating extracompartmental, typically a marker of an aggressive tumor. Then M represents metastasis, with 0 for none and 1 for presence. So, in cases where distant metastasis occurs, it generally corresponds to stage three, phase B, which involves extracompartmental invasive metastasis. In such cases, even surgery provides poor outcomes. Early detection and treatment are best. If it progresses to later or final stages, treatment is often deemed unnecessary, limited to conservative management, as surgical outcomes are poor, and metastasis may occur elsewhere.