Like most other types of cancer, kidney cancer starts as a small growth or mass which grows larger over time. However, kidney cancer can occur differently: (1) as a single mass within one kidney, (2) as multiple tumors within one kidney, or (3) as tumors in both kidneys. However, in most cases the cancer is diagnosed in early stages when the tumors have not invaded other organs or the cancerous cells have not enter the bloodstream. The kidneys are two pair-shaped organs about the size of a fist located in the posterior part of the abdominal cavity behind peritoneum, on each side of the spine. The left kidney is just below the liver, while the right one sits below the diaphragm and near the spleen. Each kidney together with the adrenal gland (which sits atop each kidney) is covered by a mass of fatty tissue and an outer layer of fibrous tissue. The kidneys receive 20 to 25 percent of the total arterial blood pumped by the heart.

The kidneys perform three vital functions for the body.

1. Excretes waste products after metabolism.
Kidneys filter the blood and remove waste products from the body as urine. The urine collects in the renal pelvis (which is the hollow space inside each kidney) and passes further into the urine bladder through the ureters (long, thin tubes that connects the renal pelvis to the bladder).

2. Homeostasis.
Kidneys regulate the pH (the acidity of the blood plasma) and water composition in the blood, and maintain a normal blood pressure.

3. Hormone secretion
Kidneys secret several hormones such as erythropoietin (a glycoprotein that stimulates the production of red blood cells), urodilatin (natriuretic peptide with cardiovascular, renal, endocrine, and pulmonary effects), renin (a proteolytic enzyme that affects blood pressure), as well as vitamin D.

Kidney Cancer Types

I. Renal Cell Carcinoma (RCC)

II. Wilms’ Tumor

III. Transitional cell carcinoma (TCC) is a less common type of cancer that develops in the renal pelvis (the draining tubes that exit the kideny). It accounts for 6 to 7 percent of all kindey tumors. This cancer looks different than renal cell carcinoma when examined under microscope and is more similar to bladder cancer. Usually, transitional cell carcinoma is treated as bladder cancer.

IV. Renal sarcoma is a rare type of kidney cancer which develops in the kidney’s connective tissues. It accounts for less than 1 percent of all kidney tumors. Its symptoms are similar with renal cell carcinoma, and can be properly diagnosed only after performing several tests (such as computed tomography or magnetic resonance imaging, and biopsy).