First, let's discuss osteosarcoma, which is the most common malignancy, predominantly found in adolescents. It often affects the metaphyseal region such as the distal femur, proximal tibia, or proximal humerus, etc. It usually presents with pain, typically persistent and more prominent at night, and the body tends to be emaciated, showing signs of cachexia. The skin over the tumor is often warm, with prominent veins and limited mobility. Diagnosing osteosarcoma requires early radiographic examination, which may show Codman's triangle, appearing like sunray patterns.

Moreover, the likelihood of pulmonary metastasis in osteosarcoma is relatively high, with early metastasis often showing no symptoms. By the mid to late stages, patients may exhibit a range of pulmonary symptoms, such as irritating cough, some may experience chest pain, or cough up blood. Some who undergo radiographic examination might already have pneumothorax. In such cases of hemothorax, we typically perform a puncture which can clearly confirm the presence of cancer cells, indicating lung metastasis.

Once lung metastasis occurs, it significantly jeopardizes life expectancy, often reducing it to about one to three months. Under such circumstances, humane care is required, along with pain management and symptomatic treatment to alleviate suffering as much as possible. Nutritionally, it is important to ensure adequate protein intake, and hematological monitoring of red blood cells, platelets, granulocytes, and hemoglobin is necessary, providing the best conservative or nutritional support to lessen the patient’s suffering.