How do you diagnose kidney cancer (renal cell cancer)?

X-rays: The vast majority of kidney cancers are diagnosed soley on radiological findings (x-rays). These tests include a ct scan and/or MRI and chest x-ray. In addition, other tests such as blood tests are also used to help aid in the evaluation of metastatic disease. Kidney biopsies are rarely indicated to make the diagnosis.

Kidney cancer: Typically by ct scan or mri.

Removal: As mentioned by others, it is usually not needed to biopsy a kidney tumor once it is found by imaging, since renal cell carcinomas have a characteristic appearance by x-ray studies. However, a small percentage of these tumors once removed are found to be benign (noncancerous). So the final tumor type is not 100% confirmed until it is removed.