What is the reason for the weakness of both lower extremities in patients with lung cancer? Four reasons to pay attention to, how to prevent?

Uncle Li, 76 years old, has adenocarcinoma of the apex of the lung. He has undergone radiotherapy and chemotherapy. Every time the chest CT is reviewed, it shows that the lesions are well controlled. But Uncle Li has a new distress. He said that he eats a lot every day, but he always feels weak, weak in both lower limbs, and sometimes feels like he is stumbling when walking. What could be causing this situation?

Lung cancer patients with bilateral lower extremity weakness may have multiple causes:

lumbar spine metastases

When cancer cells metastasize to the lumbar spine and destroy the vertebral bone tissue, it will cause spinal instability. After all, the lumbar spine is weight-bearing. When the tumor compresses the spinal cord, it may even develop into paraplegia, with complete loss of lower extremity motor and sensory function. I have met many patients with thoracolumbar metastases from lung cancer, who eventually became paraplegic, unable to take care of themselves, and unable to pass urine and feces.

Brain metastases

The brain is the center of the human body, directing the movement of the muscles of the whole body. When a functional area of ​​the brain is transferred, it may cause motor dysfunction, but the movement disorder of patients with brain metastasis is usually unilateral . For example, metastases in the left brain can cause motor and sensory disturbances in the right limb.

Cancer fatigue

Cancer fatigue is also known as cancer-related fatigue, or CRF for short. CRF is regarded as the sixth vital sign after body temperature, pulse, respiration, blood pressure and pain. Cancer-related fatigue can exceed 75% in advanced cancer patients, and more than 40% of postoperative patients experience fatigue. There are many reasons for cancerous fatigue, one of which is that tumor cells secrete some substances, such as interleukin-1, interleukin-6, tumor necrosis factor, etc., which induce cancerous fatigue.


With the widespread use of immunotherapy in clinical practice, more patients with advanced lung cancer use immunotherapy, but PD1/PD-L1 inhibitors have a fairly common adverse reaction, namely immune-related thyroid function Decreased, referred to as hypothyroidism. Common symptoms of hypothyroidism are fatigue, loss of appetite, memory loss, unresponsiveness and so on. Subclinical hypothyroidism is very insidious, and there may be no other special symptoms except fatigue. Using immunotherapy, routine blood tests will be performed to check thyroid function, and if hypothyroidism occurs, thyroxine replacement therapy should be supplemented in time.

When lung cancer patients have unexplained weakness in both lower extremities, relevant examinations should be carried out in time, including thoracolumbar MRI, and head MRI to rule out whether there is metastases in the corresponding parts. For brain metastases or limited bone metastases, local radiotherapy can be considered, and mannitol and steroid dehydration are required.

For patients with no brain metastases and advanced vertebral metastases, the possibility of cancerous fatigue is high. The treatment of cancerous fatigue includes: 1. Strengthen nutrition and supplement high-quality protein; 2. Exercise properly; 3. Maintain a good attitude and ensure enough sleep; 4. Drug treatment: the central stimulant methylphenidate can be considered for severe fatigue Or short-term use of cortisol hormones can increase traditional Chinese medicines and proprietary Chinese medicines, such as Zhengyuan Capsules, Fuzheng Capsules, etc. to improve fatigue. Thymus Faxin has also been included in the 2021 edition of the Chinese Cancer-related Fatigue Clinical Practice Diagnosis and Treatment Guidelines.