From the Guidelines
Muscle weakness is strongly associated with renal cancer, primarily due to cancer cachexia, systemic inflammation, and paraneoplastic syndromes, which can lead to significant morbidity and mortality. The relationship between muscle weakness and renal cancer is complex, involving multiple mechanisms that contribute to muscle wasting and fatigue. According to the ESPEN guidelines on nutrition in cancer patients 1, muscle mass below certain thresholds is strongly associated with mortality in cancer patients, as well as complications of cancer surgery and dose-limiting toxicity during systemic anti-cancer therapy.
Some key factors that contribute to muscle weakness in renal cancer patients include:
- Cancer cachexia, characterized by progressive weight loss, muscle atrophy, and fatigue
- Systemic inflammation, which can lead to altered protein turnover, loss of fat and muscle mass, and increased production of acute phase proteins 1
- Paraneoplastic syndromes, where the cancer produces hormones or triggers immune responses that affect muscle function
- Hypercalcemia, which can cause muscle weakness and fatigue
- Direct tumor invasion or metastasis to bones or nerves, which can compromise muscle function
- Treatment-related factors, including side effects from chemotherapy, targeted therapies, and immunotherapies
The ESPEN guidelines also highlight the importance of addressing weight loss, impaired physical performance, and systemic inflammation in cancer patients, as these factors are independently associated with an unfavorable prognosis, increased toxicity of anticancer treatments, and reduced quality of life 1. Therefore, management of muscle weakness in renal cancer patients should prioritize a multidisciplinary approach, including oncological treatment, physical therapy, nutritional support, and correction of metabolic abnormalities. Patients experiencing muscle weakness should be evaluated promptly, as it may indicate disease progression or treatment complications.
From the Research
Association between Muscle Weakness and Renal Cancer
- Muscle weakness has been reported as a symptom in patients with renal cell carcinoma (RCC) in several studies 2, 3, 4, 5.
- In some cases, muscle weakness is associated with paraneoplastic syndromes, which are conditions that occur in response to the presence of cancer in the body, but are not due to direct local effects of the cancer cells 2, 3, 4, 5.
- For example, a study reported a case of a patient with RCC who developed demyelinating peripheral neuropathy, which caused progressive gait disturbance and muscle weakness 2.
- Another study reported a case of a patient with RCC who developed a motor neuron disease resembling amyotrophic lateral sclerosis, which caused muscle weakness and fasciculations in the upper extremities 3.
- In some cases, treatment of the underlying cancer can lead to improvement or resolution of the muscle weakness and other symptoms associated with the paraneoplastic syndrome 2, 3, 5.
- However, in other cases, muscle weakness may be a side effect of cancer treatment, such as tyrosine kinase inhibitors, which can cause a decrease in skeletal muscle area and lean body mass 6.
- Additionally, immune checkpoint inhibitors, which are used to treat certain types of cancer, including RCC, can cause immune-related adverse effects, including muscle weakness and myasthenia gravis 4.
Paraneoplastic Syndromes and Renal Cancer
- Paraneoplastic syndromes are rare disorders that are triggered by the immune system's response to cancer, and can occur in patients with RCC 2, 3, 4, 5.
- Examples of paraneoplastic syndromes that have been reported in patients with RCC include demyelinating peripheral neuropathy, motor neuron disease, myasthenia gravis, and dermatomyositis 2, 3, 4, 5.
- These syndromes can cause a range of symptoms, including muscle weakness, fatigue, and neurological dysfunction, and can be difficult to diagnose and treat 2, 3, 4, 5.
- In some cases, treatment of the underlying cancer can lead to improvement or resolution of the paraneoplastic syndrome, while in other cases, treatment of the syndrome itself may be necessary 2, 3, 5.