Metastatic kidney cancer is a more challenging disease to manage when compared to localized cancer because it is more difficult to completely eliminate the cancer when it has spread to multiple organs in multiple places in the body. When kidney cancer is confined to the kidney, surgery alone is most often curative because the entire cancer is removed, so there are no more cancer cells remaining in the body.
In contrast, when metastatic kidney cancer is present, there are cancer cells outside of the kidney. These are difficult to treat surgically because many metastases are difficult to remove (i.e. removing every lymph node affected with cancer may not be possible) or because removing the metastatic disease may be too dangerous (i.e. when large portions of the lung or brain are affected). Also, once kidney cancer has been documented to metastasize to another part of the body, there are often microscopic deposits of the cancer (these can be just a few kidney cancer cells) that can not possible to detected by any tests that doctors currently have at their disposal. As such, removing all the metastatic kidney cancer that we can find may not completely eliminate the entire disease.