All cancers will show symptoms of weakness, especially in the middle and late stage cancer patients. With the aggravation of the disease, poor physical condition, abnormal liver and kidney function, and declining heart and lung function, the weakness and weakness of legs will be obvious, and in serious cases, they may even be bedridden. In addition, cancer patients will suffer from bone marrow suppression during radiotherapy, such as leukopenia and anemia, which will also lead to weakness and weakness of legs. During targeted therapy and immunotherapy, one of the side effects of treatment is weakness and lack of energy in the legs. In conclusion, no matter what kind of cancer, all patients may experience weakness due to the side effects of the disease and treatment. Clinicians should actively deal with patients according to their symptoms to improve their quality of life.