Your kidneys are two bean-shaped organs located below your rib cage on the right and left side of the posterior part of your abdominal cavity. Each kidney is equipped with an excretory canal called ureter, which descends vertically in your retroperitoneal region (anatomical space behind your abdominal cavity), then into the pelvis to your bladder. The kidneys play major roles in your body; they are responsible for many vital functions including purification and secreting urine. However, they may be affected by many disorders, including cancer.
Kidney cancer, also called renal cancer, begins as a malignant tumor that develops in your kidney tissue. A kidney cancer can be primary, meaning that the cancer begins directly in the cells of the kidney. The cancer can also be a metastasis from a primary cancer of another organ that has migrated into your kidney. In this case, the tumor is called secondary kidney cancer.
Kidney Cancer Statistics
Kidney cancer is a rare form of cancer, accounting for 2 to 3% of all adult cancers. It is estimated that about 208,500 people are affected with kidney cancer in the world each year, with the highest rates in Northern America and the lowest rates in Asian and African regions. In the United States, about 49,096 people were diagnosed with kidney cancer in 2009 with around 11,033 dying of it.
The incidence of kidney cancer varies with age. From 2002-2006, the median age at diagnosis for cancer of the kidney and renal pelvis was sixty-four years of age; the percentages and ages of people diagnosed were approximately:
- 1.3% were under age 20
- 1.5% were between 20 and 34
- 6.1% were between 35 and 44
- 16.4% were between 45 and 54
- 24.6% were between 55 and 64
- 24.3% were between 65 and 74
- 20.0% were between 75 and 84
- 5.7% were 85+ years of age.
Kidney Cancer Causes
The kidneys are two bean-shaped organs located in your abdomen, specifically on each side of your spine, in the lower part of the thorax between the 11th vertebra and the 3rd lumbar (the left kidney) and between the 12th vertebra and the space between the 3rd and 4th lumbar (the right kidney). The kidneys continually filter water, impurities and waste from the blood, and produce urine. You need them to have a clean and healthy body.
Kidney cancer occurs when cancer cells grow abnormally in the membrane that lines the small tubes within your kidneys. The causes of the transformation of healthy cells into cancerous ones are not clear to scientists, but risk factors are suspected (see Risk Factors).
Kidney Cancer Risk Factors
Kidney cancer is a multifactorial disease; several factors seem to contribute to its development. The two main risk factors of kidney cancer are tobacco and hypertension. The longer you smoke or suffer from an untreated hypertension, the higher your risk. Other factors suspected in the development of kidney cancer include:
- Age – Kidney cancer is diagnosed mainly after fifty; if you are sixty or older, your risk is even higher.
- Sex – Kidney cancer affects more men than women; the disease is estimated to be three times more common among men.
- Certain occupations – You are at greater risk of kidney cancer if you work in an industry that implements or manufactures iron and steel from ore.
- Chemicals in workplace – If your job constantly exposes you to oil derivatives, heavy metals and asbestos, your chances of becoming a victim of kidney cancer increases.
- Obesity – If you are obese/overweight, you have a higher risk for developing renal cell carcinoma.
- Certain medications – Prolonged use of phenacetin, a painkiller, is linked to kidney cancer. Fortunately, the drug has been removed from the market in the United States since early 1980s.
- Treatment for kidney failure – If you had a kidney transplant or dialysis for a long period to treat chronic kidney failure, you are at higher risk to develop kidney cancer.
- Genetic mutation – Certain inherited diseases such as Von Hippel-Lindau disease tend to contribute to the development of many cancers, including renal cell carcinoma.
Types of Kidney Cancer
There are several types of kidney cancer, depending on the type of cells or tissue affected:
- Renal cell carcinoma – A kidney cancer is considered as renal cell carcinoma (also called hypernephroma) when the tumor begins in the lining of the small tubes in the kidney that filter the blood and remove waste products; the cancer may affect one or both kidneys. Renal cell carcinoma is the most common form of kidney cancer and accounts for nearly 90% of all kidney cancer cases.
Some subtypes of renal cell carcinoma include:
- a) clear cell renal cell carcinoma
- b) papillary renal cell carcinoma
- c) chromophobe renal cell carcinoma
- d) collecting duct renal cell carcinoma
- Transitional cell carcinoma (TCC) – Also called urothelial cell carcinoma (UCC), transitional cell carcinoma it is the second most common form of kidney cancer. A kidney cancer is considered as an urothelial cell carcinoma when the tumor develops in the tissue of the tubes that connect the kidneys to the bladder. Transitional cell carcinoma is responsible for 5-10% of all kidney cancers.
- Wilms tumors – This rare form of kidney cancer affects children less than five years old and is rarely diagnosed in adults. Approximately five hundred children in the United States are affected by it each year.
- Renal sarcoma – This rare type of kidney cancer usually begins in the kidney’s connective tissue. It is an aggressive tumor requiring complete surgical extirpation to prevent complications. Renal sarcoma represents about 1% of all kidney cancer cases.
Kidney Cancer Symptoms
Kidney cancer may be asymptomatic for a long period of time. Although the tumor is growing in your kidney, it causes no significant signs or symptoms that indicate its presence. When you finally experience pain, the cancer is already advanced.
Some kidney cancers are detected during an ultrasound or radiography performed for another medical condition. However, as the cancer is completely installing in your kidney, you may experience severe pain.
Although these symptoms below are not necessarily indicators of kidney cancer, they are often signs that indicate not only that you have the disease but it is already advanced.
- blood in your urine
- perceptible lump or mass in the region of your kidneys
- persistent abdominal or back pain just below your ribs
- intermittent fever
- unexplained weight loss
- general malaise
Kidney Cancer Complications
If you have renal cell carcinoma, you may experience the following complications:
high calcium level
high red blood cell count
liver function abnormalities
rupture of the kidney
damage to the entire kidney
spread of the cancer to your brain, lungs, bone, and liver (metastatic kidney cancer)
Kidney Cancer Diagnosis
Your doctor can begin the diagnosis by asking you questions about the symptoms you experience and your medical history. He will do a physical examination searching for signs indicating the presence of the cancer. In addition, he will recommend blood and urine tests to detect kidney failure and look for presence of blood in your urine.
However, confirmation of the diagnosis is based on biopsy and imaging techniques like the ultrasound, CT, MRI, and intravenous urography (UVI).
Ultrasound, CT & MRI – An abdominal ultrasound or CT scan allows your doctor to see if the renal vessels and the surrounding tissue are affected or compressed by the tumor. A chest x-ray and CT scans can be performed to search for lung metastases. The role of the abdominal MRI is to clarify the extent of the tumor in the renal area and detect if it has spread.
Biopsy – A renal biopsy is an essential procedure in the diagnosis of kidney cancer. During the exam, your physician removes a tiny sample of cells from your diseased kidney. To get access to the renal tissue, the physician can perform a transcutaneous intervention, use of a needle or a trocar, or open surgery, done through skin incision.
Open biopsies are rare and are usually performed by an experienced surgeon. Although useful, open biopsies are accompanied with a risk of infection and bleeding. In addition, the biopsies can cause the tumor to spread to other areas of your body.
Intravenous urography (IVU) – Also called intravenous pyelogram, an IVU is a painless medical procedure that enables your physician, after intravenous injection of a contrast agent, to visualize and examine your urinary tract organs including the kidneys, ureters, and bladder. Using this test, it is possible for your doctor to detect abnormalities such as malformations, tumors, or stone in the ureter.
Kidney Cancer Stages
Once the diagnosis is confirmed, your oncologist will assess the extent of the tumor to determine the stage of the cancer. In general, the cancer stage is determined based on the size of the tumor and degree of the cancer cells that have spread within your body. Staging is important for your oncologist to choose the most effective treatment and determine the prognosis.
In general, the stages of kidney cancer are determined by Roman numerals: I, II, III and IV. The higher the stage, the less likely you are to survive.
- Carcinoma in situ – Also called stage 0, carcinoma in situ indicates the genesis of the cancer.
- Stage I – In this early stage, the cancer is small and confined to the kidney.
- Stage II – At stage2, the tumor has increased in size, but has not spread yet.
- Stage III – The cancer has spread to the surrounding areas or the adrenal glands; in certain cases, the tumor may have also spread to a nearby lymph node.
- Stage IV – The cancer has affected not only surrounding tissue of the kidney but also distant parts of your body: brain, lungs, and bone or/and liver.
Kidney Cancer Treatment
To determine an appropriate treatment, your doctor will consider the type, grade (degree of malignancy), and stage of your cancer. He can also rely on your general health and age. These factors are very important when it comes to chemotherapy drugs. However, whatever the treatment considered, you will be invited to participate in the final choice.
In general, treatment of kidney cancer is a combination of surgery, radiotherapy, chemotherapy, and immunotherapy. However, chemotherapy and radiotherapy produce almost no effect on kidney cancer.
The treatment of kidney cancer is primarily surgical. The type of surgery performed depends on the characteristic (aggressive or not) of the tumor. Your surgeon will perform radical nephrectomy, simple nephrectomy, or partial nephrectomy.
Radical nephrectomy – This type of surgery is performed to remove the entire kidney, the adrenal gland located above the kidney, and adjacent lymph nodes. If you have a localized kidney cancer, radical nephrectomy is the standard surgical treatment to fight the tumor.
Partial nephrectomy – This surgical procedure involves the removal of the tumor and some of the surrounding tissue; a portion of the kidney and surrounding normal tissue is left. Your surgeon will perform a partial nephrectomy if the cancer affects both kidneys, or if you have a previous renal operation that leaves you with only one kidney.
Simple nephrectomy – This surgery consists of removing only your kidneys; nearby lymph nodes are left intact. A simple nephrectomy is recommended in cases of kidney cancer diagnosed at the early stage or if a small-size tumor is confined to the kidney.
Non surgical treatment
Embolization – This method involves injecting a material into your blood vessel leading to the kidney to block blood flow to the tumor. Once blood flow to the kidney is stopped, cancer cells become starved of oxygen and other nutrients to survive. However, embolization may cause nausea, vomiting, or pain.
Cryoablation – This therapeutic procedure consist of using hollow needles (cryoprobes) to freeze the diseased kidney. During the procedure, your physician inserts cryoprobes through small incisions in your skin and into the tumor, through which cooled, thermally conductive fluids are circulated down to your kidneys to freeze the diseased tissue along with a small margin of healthy tissue. During the procedure, you doctor will use CT scan to monitor the progression of the therapy.
Chemotherapy and radiotherapy
In some cases, some doctors may recommend chemotherapy or radiotherapy to destroy cancerous cells in your kidneys; however, chemotherapy and radiotherapy produce almost no curative effect on kidney cancer.
In case you have a metastatic kidney cancer, your doctor may use special medications to slow or stop the development and division of the cancerous cells. Drugs commonly used in the treatment of metastatic kidney cancer include:
- bevacizumab (Avastin)
- sorafenib (Nexavar)
- sunitinib (Sutent)
- temsirolimus (Torisel)
- everolimus (Afinitor)
Unfortunately, some times, the treatment offers no relief; metastatic kidney cancer rarely responds to drug treatment.
Kidney Cancer Survival Rates
Kidney cancer prognosis depends on the size and stage of the tumor. The earlier the cancer is diagnosed, the more chance you have to survive. In addition, if your overall health is more or less in good condition, the prognosis is better because you will be able to undergo a stronger treatment.
According to the National Cancer Institute (NCI), the overall 5-year relative survival rate for kidney cancer for 1999-2005 was 68.4%. The survival rates vary by race and sex. Five-year relative survival rates for blacks and whites in the United States were:
- 68.1% for white men
- 69.1% for white women
- 64.7% for black men
- 67.4% for black women
Kidney Cancer Prevention
Since the causes of kidney cancer are well known, it is not possible to fully prevent it. However, to prevent the occurrence of almost all types of cancer, including kidney cancer, it is necessary to live a healthy lifestyle. Your lifestyle as well as your environment can lead to development of cancer cells in your kidney.
Several factors can cause formation of cancerous cells in your body. Some risk factors such as sex and age are impossible to avoid; others, however, can be prevented. If you want to prevent kidney cancer and many other cancers, you need to:
- Avoid chemical exposure.
- Avoid working in industries that implement or manufacture iron and steel from ore.
- Avoid tobacco smoke, including second hand smoke.
- Adopt a healthy diet: a diet containing 5 to 10 servings of fruits and vegetables a day may help prevent occurrence of kidney cancer.
- Maintain a healthy weight.
- Limit your alcohol intake.
- Reduce your exposure to ultraviolet (UV) radiation.
- Exercise regularly.
- Take all abnormal bleeding seriously.
- Practice safe sex.
- Tell your doctor or dentist of any change that indicates the presence of cancer.