Lung cancer will not cause leg pain, but if leg pain occurs, there may be the following two conditions: 1. related to the original disease, related to the condition, mostly consider whether there is bone metastasis, one of the metastatic ways of lung cancer is blood metastasis, among which the most common location of blood metastasis is bone, so there is pain and even pathological fracture in the lower limbs; 2. related to treatment, related to treatment drugs and treatment methods. For example, chemotherapy drugs, like paclitaxel, the main side effect is muscle pain all over the body, especially the lower limbs mainly, and part of the whitening drugs used in the chemotherapy process, the side effect can also make muscle pain all over the body, especially the lower limbs. The treatment process requires infusion of fluids and intramuscular injection of drugs can also cause corresponding pain. Therefore, to determine the different causes and take different methods, this is the main way to deal with it.