As with all cancers, kidney cancer and benign tumors evolve from a disruption in one or more genes in a cell's DNA. Genes control cell activities including division and growth. When cells die, a normal and common event, they are replaced by new cells as the body needs them. However, when the genes that orchestrate this natural replacement process are disrupted by chemicals, illness, or other unknown factors, control over cell division and growth is lost. The resultant uncontrolled mass of tissue is a tumor.

Approximately 85% of all kidney cancers are renal cell carcinoma (RCC). This cancer develops in the tubules and is usually a single tumor although there have been instances in which there are more than one tumor. Transitional cell cancer (TCC) of the renal pelvis is less common accounting for about 8% of diagnosed cancers. Treatment for TCC is similar to treatment for bladder cancer.

Sarcomas are malignant tumors growing from connective tissues, such as cartilage, fat, muscle or bone. They comprise approximately 3% of kidney cancers. Wilms' Tumor, a kidney cancer, affects infants and children and is rare. This kidney tumor usually appears before a child is three-years-old.

There are also a variety of benign growths. These are actually tumors but they are usually non-threatening initially. The five principal benign tumors are renal adenoma, renal oncocytoma, angiomyolipoma, fibroma and lipoma. The adenomas are the most common. Oncocytomas are not unique to the kidneys and can appear throughout the body. Angiomyolipomas are inherited and are associated with rare genetic disease called tuberous sclerosis. Fibromas are rare tumors that originate in the fibrous tissue in and around the kidney. They are more common in women. Lipomas originate in fat cells in and around the kidneys. They have the potential for becoming cancerous and are usually treated with nephrectomy – removal of the kidney. Most of these kidney tumors appear without symptoms and are usually discovered incidentally in the course of a routine examination or found while pursuing a diagnosis for another problem.
  Kidney cancer, which most often occurs in men 50 to 70 years old, rarely produces symptoms in its early stages. Eventually, though, a tumor in one of the kidneys may trigger one or more of the following:

• blood in the urine (most common symptom)
• persistent pain in the back, just below the ribs
• a lump in the abdomen
• general symptoms such as persistent fatigue, unexplained weight loss, recurrent fevers, high blood pressure, swelling in the ankles
• Being aware of these signs can help patients catch their condition and begin treatment as soon as possible.

Options for treating kidney cancer include surgery to remove the kidney, chemotherapy, radiation therapy, hormone therapy, and biological or immunotherapy. Sometimes, when the disease is tightly confined, treatment may involve removing only the affected portion of the kidney. This procedure is called a partial nephrectomy or nephron-sparing surgery and can help preserve the function of the involved kidney.
  The very early stages of kidney tumor growth seldom prompt symptoms but as the tumor grows it makes its presence known. Individuals may notice a persistent pain in their back just below the ribs. The doctor may note a lump or mass during a physical examination. Other more general symptoms of a kidney tumor may include persistent fatigue, unexplained weight loss, recurrent fevers, high blood pressure (hypertension), swelling (edema) in the ankles, a feeling of poor health, and blood in the urine (hematuria).
  The majority of the cancers appear in people between the ages of 40 and 70 and in men about twice as frequently as women. Smokers are far more likely to develop cancer than non-smokers. It is estimated that if all smokers quit, the appearance of certain kidney cancers would drop by half. Pain killers, such as over the counter medications containing phenacetin, have been linked to kidney cancers. These were pulled from the market 20 or more years ago but some older people who used them may still be at risk.

High fat diets, excessive weight and hypertension are risk factors. Workers exposed to asbestos or cadmium, an ingredient in inks and paints, are at a slightly higher risk. Genetics play a role. People who have a history of kidney cancer in their immediate families are at higher risk, especially if they smoke or have been exposed to the aforementioned chemicals.
   
Diagnosis begins with a thorough physical examination followed by a series of laboratory tests and imaging procedures to identify the location and extent of the kidney tumor.
  Urinalysis – Urinalysis is a common test to detect microscopic blood that might not be seen on visual examination.

Cystoscopy - A number of problems cause blood in the urine. The examining doctor will examine the urinary tract for other disorders by inserting a thin tube equipped with optics through the urethra to examine the urethra, bladder and kidneys. Cystoscopy also allows the doctor to remove small samples of tissue from suspicious growths for examination.

Blood tests – Blood tests are conducted to detect anemia (loss of blood cells caused by internal bleeding), polycythemia (excessive blood cells caused by hormones released by the tumor), and hypercalcemia (high calcium levels).
  One or more procedures may be conducted to identify abnormalities in the kidneys. Among these are computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, intravenous pyelogram, chest x-ray, and bone scan. The first four procedures identify the location and size of the kidney tumor. The latter two may be employed to determine if kidney cancer cells have spread to other parts of the body.
  Fine needle aspiration – When a kidney tumor has been located, a physician may occasionally use a needle to draw a sample of fluid from the tumor to allow a pathologist to examine it. This will help the pathologist and physician determine the nature of the cancerous cells and stage the kidney tumor.
  Kidney cancer treatment is determined after assessment of all clinical information, consultation with several specialists and consultation with the patient and his or her family. All options, their potential side effects, and outcomes are considered. Second opinions are frequently sought. Kidney cancer treatment falls into five categories: surgery, chemotherapy, radiation therapy, hormone therapy, and biological or immunotherapy.
  Sometimes when the disease is tightly confined to a specific region of the kidney, only the affected portion is removed in a procedure known as a partial nephrectomy, or nephron sparing surgery.
The gold standard surgery for kidney cancer is removal of the affected kidney. Removal of a single kidney is a simple nephrectomy while removal of the kidney and accompanying adrenal gland (atop the kidney) is a radical nephrectomy. A bilateral nephrectomy is the removal of both kidneys.

Patients are often given the option of either a standard open procedure or a laparoscopic procedure. In the standard open procedure an incision is made in the side and the kidney is removed with minimal disturbance to adjacent organs. Sometimes the nature of the cancer or health status of the patient requires that the kidney be approached from the front of the abdomen or the patient’s back.
During laparoscopic partial nephrectomy procedures, incisions no more than a few inches are made and narrow tubes are inserted into the abdomen near the kidneys. Video and surgical instruments are inserted through the tubes to allow the surgeon to conduct the procedure. The advantages of a laparoscopic partial nephrectomy include minimal trauma, reduced blood loss, reduced hospital stays, faster recovery, and less scarring.
  Recurrence of the disease is a concern with all kidney cancer patients. Patients undergoing surgery will undergo re-examination at three-month intervals for at least the first year following the operation. These examinations usually include a full physical examination, blood tests, x-rays, and evaluations of liver and kidney functions.
  As noted, the gold standard for kidney cancer treatment is surgery. Other procedures may be used as secondary treatments or primary treatments when surgery is not permitted by other conditions the patient may have.

Radiation therapy – Cancer cells, because they are continually growing and dividing, are particularly sensitive to high energy radiation. This can be delivered as a tightly focused beam or as small pellets inserted in the tumor (Brach therapy). Both procedures are guided by computers so that the radiation field created internally conforms to the shape of the tumor. Radiation is sometimes used as a secondary treatment to destroy cells that may have escaped removal by surgery.

Chemotherapy – A number of chemotherapeutic agents are being developed to destroy cancer cells in the kidney and throughout the body. Unfortunately renal cell carcinoma (RCC) has proven to be particularly resistant to these drugs. Research to develop more effective drugs is proceeding.
  Cryotherapy – A thin metal probe is inserted into the tumor and liquid nitrogen is circulated through the tip to freeze and destroy the tissue. This procedure has been used in a number of patients but it remains in its early stages. The success rate is good but the patients need to be followed for a number of years to determine how frequently the cancer might recur.

Radiofrequency tumor ablation (RFA) – This kidney cancer treatment involves the placement of several needles into the tumor. Radio waves heat the tumor and destroy it in a manner similar to thermotherapy. Early trials in kidney cancer indicate that several treatments may be needed. The advantage of this treatment is that there are no incisions and patients can return home shortly after the treatment. The treatment is still in the early stages and patients who have undergone the procedure in careful clinical trials need to be followed for several years to determine its effectiveness.

Vaccines – The vaccines that are being developed for kidney and other cancers are not designed like normal vaccines to prevent the disease but rather to treat those who already have it. These vaccines are designed to induce the body’s immune system to recognize tumor cells and destroy them with natural biological responses. If successful, should allow the body to destroy these cells no matter where they might lurk in the body and help prevent recurrence. All vaccines are currently experimental.

Anti-angiogenesis agents – Angiogenesis is the term given to the growth and development of blood vessels. Anti-angiogenesis drugs are designed to prevent such growth. Tumors are continually growing and need a constant blood supply to feed them. Anti-angiogenesis drugs, by inhibiting or preventing the growth of new vessels, literally starve growing tumors. These drugs received substantial publicity a few years ago but designing new agents, especially those that constitute an entirely unique biological approach, takes an immense amount of time to develop. These kidney cancer treatments remain experimental.