Metastatic kidney cancer affects the body in a number of ways. When advanced cancer is present, patients begin to lose weight in a process known as cachexia (pronounced ka-kek-sia). Symptoms of cachexia include loss of lean body mass (like muscle), increased metabolic rate, and decreased intake of food. It seems as though the body is wasting away.
The exact mechanism for cachexia is unknown, although a number of factors are thought to be involved in the process. Kidney cancer cells produce chemicals known as cytokines, including tumor necrosis factor alpha (TNF-a) and interleuken-6 (IL-6). Both of these chemicals have been shown to lead to cachexia, and numerous studies have shown high levels of TNF-? and IL-6 in patients with symptoms of cachexia. In addition to the effects of cytokines, cancer and its treatment can lead to alterations in the way food tastes. As such, food may loose its appeal. The combination of decreased appetite and the diminished appeal of food leads to decreased food intake. Patients who are eating less and burning more calories through an increased metabolic rate will lose weight.
Another challenge of metastatic kidney cancer is that it can spread to other organs and affect other systems in the body. One of the most common places that kidney cancer can spread to is the lungs. These lung metastases can impair the functioning of the lungs, making it harder to breathe. Often, removing the lung metastases of kidney cancer involves removing significant portions of the lung, which can further decrease lung function. Metastases of kidney cancer to the liver can lead to fever, weight loss, and decreased liver function. Bone metastases of kidney cancer can lead to bone pain and fractures that do not heal well. Finally, brain metastases can be dangerous because they may directly invade important areas of the brain or lead to compression and damage of brain tissue. Compression results from the tumor quickly growing to a large size. When these tumors are removed from the brain, important brain tissue may be removed with the tumor, which can also create problems.