What is Kidney Cancer?
Kidney cancer is cancer that affects the kidneys. Kidneys are the bean-shaped organs in the lower back that filter waste from the blood, which is then excreted through urine. The kidneys play a crucial role in maintaining balanced electrolyte levels in the blood, and they also create hormones that regulate blood pressure and red blood cell count.
Cancer forms when cells mutate and replicate uncontrollably. These mutated cells can form tumors and damage healthy tissue. Different types of cancer can develop in the kidneys based on the location in which the cancer originates. When cancer arises in the kidneys, it is usually in the renal cells that line the tiny tubes where blood is filtered. If kidney cancer prevents the kidneys from functioning properly, waste can build up to dangerously high levels in the body. Complications such as high blood pressure, anemia, weak bones, nerve damage, and heart and blood vessel disease could occur.
Types of Kidney Cancer
Types of kidney cancer include:
- Renal cell carcinomas (RCC) - This is the most common type of kidney cancer, accounting for almost 90% of diagnoses. RCC usually produces a single tumor, but it could cause the growth of multiple tumors on one or both kidneys. Various subtypes of RCC are determined by the appearance of the cancer cells when analyzed microscopically.
- Clear renal cell carcinoma - The most common type of RCC, and the cancer cells look pale or clear
- Non-clear cell renal cell carcinoma - This subtype includes papillary renal cell carcinoma, which causes projections (papillae) in the tumor. It also includes chromophobe renal cell carcinoma. There are other rare types, including collecting duct RCC, multilocular cystic RCC, medullary carcinoma, mucinous tubular and spindle cell carcinoma, and neuroblastoma-associated RCC.
- Unclassified renal cell carcinomas – Do not have characteristics that fit with the other subtypes mentioned, or they have more than one type of cancer cell
- Transitional cell carcinomas - This type of kidney cancer begins in transitional cells that line the renal pelvis (the part of the kidney that connects to the ureter). Less than 10% of kidney cancers are of this type, and they often share symptoms with renal cell carcinomas.
- Wilms tumors - Also known as nephroblastoma, this type of kidney cancer almost always affects children. Most Wilms tumors are unilateral, meaning they are only present in one kidney, but rarely they can be bilateral, affecting both kidneys. In many cases, the tumors have grown quite large before they are detected. There are two subtypes of Wilms tumor based on how the cells look when analyzed microscopically:
- Tumors with anaplastic histology - These have a condition known as anaplasia, in which the cancer cells have large, distorted nuclei
- Tumors with favorable histology - The cancer cells do not have anaplasia, though they still do not look normal. Most Wilms tumors have favorable histology, and there is a high chance of curing children with this type of tumor.
- Renal sarcomas - This cancer originates in the kidney's blood vessels or connective tissue. This type of cancer is rare, accounting for less than 1% of kidney cancers.
Benign (noncancerous) tumors can also grow on the kidneys, but they will not spread to other body locations. Still, they can interfere with normal kidney function as they grow, so they may require the same treatment methods used for kidney cancers.
Stages of Kidney Cancer
Stages of kidney cancer are based on how the condition has progressed and where the cancer has spread. The experts at NewYork-Presbyterian use diagnostic tests to determine the cancer's stage and the most effective treatment approach for each patient.
The stages of kidney cancer are:
- Stage 1 - Cancer is only in the kidney and the tumor has a diameter of 7 cm or less
- Stage 2- Cancer is still only in the kidney, but the tumor is larger than 7 cm
- Stage 3 - Cancer has spread to a major vein or to nearby tissue around the kidney. The cancer has not spread to the adrenal gland, which produces hormones that regulate body functions like heart rate and blood pressure. The cancer has not spread beyond the Gerota's fascia, which is the layer of tissue surrounding the kidneys.
- Stage 4 - The cancer has spread beyond the Gerota's fascia and may grow into the adrenal gland. Cancer at this stage may have spread to other body parts or lymph nodes.
Signs & Symptoms of Kidney Cancer
If you have kidney cancer, you may not notice signs or symptoms while the disease is in its early stages. As the condition progresses, the following symptoms can develop:
- Blood in the urine
- Persistent pain in the side
- Lump or mass in the side or the abdomen
- Unexplained weight loss
- Loss of appetite
- Anemia (low red blood cell count)
- High blood pressure
Kidney cancer symptoms are similar in males and females. However, in males, the sudden formation of a cluster of enlarged blood vessels around a testicle, particularly the right testicle, can indicate the presence of a kidney tumor.
Conditions other than kidney cancer can also cause some of these symptoms. If you’re experiencing symptoms of kidney cancer, your doctor can help determine a proper diagnosis and treatment plan.
What Causes Kidney Cancer?
Kidney cancer occurs when kidney cells develop mutations in their DNA. DNA is the genetic code in all cells that provides instructions for normal cell function. Mutations are changes in this genetic code, which can cause the cells to grow and replicate in an abnormal way.
The mutated cells can damage healthy tissue in the area and also metastasize or spread to lymph nodes or other areas of the body. It is unclear what causes most kidney cancers, but certain factors can increase or decrease the likelihood of developing kidney cancer.
Certain factors will increase a person's risk of developing kidney cancer. These risk factors include:
- Age - The risk of kidney cancer increases with age
- Smoking - Smoking increases the chances of renal cell carcinoma
- Sex - Men are almost twice as likely as women to develop kidney cancer. This could be because more men than women have smoked, and men have been more likely to be exposed to carcinogens in the workplace.
- Race - African-Americans have a slightly higher risk of developing kidney cancer than people of other races. However, the reasons for this are not understood.
- Obesity – Obesity is believed to change certain hormones and thus increase the chance that kidney cancer will develop
- Workplace chemicals - Exposure to chemicals such as cadmium, asbestos, some herbicides, benzene, and organic solvents, especially trichloroethylene can increase risk
- Family history of kidney cancer - The risk is higher in people whose family members have had kidney cancer. This could be due to shared genes or shared environmental conditions.
- Certain inherited syndromes - Including hereditary renal oncocytoma, hereditary papillary renal cell carcinoma, hereditary leiomyoma-renal cell carcinoma, von Hippel-Lindau disease, Birt-Hogg-Dube (BHD) syndrome
- Advanced kidney disease - Those with advanced kidney disease, particularly those requiring dialysis treatment, have an increased risk of developing kidney cancer
- High blood pressure - The risk of kidney cancer is higher in people with high blood pressure
- Certain medications - Using phenacetin-based analgesics and diuretics increases the risk of renal cell carcinoma. Studies suggest that acetaminophen, a common over-the-counter pain reliever, also increases the chance of kidney cancer.
Since many risk factors for kidney cancer involve lifestyle choices, preventative actions can be taken to reduce the risk of kidney cancer, including:
- Quitting smoking - Smoking increases the likelihood of developing many medical conditions, including kidney cancer
- Maintaining a healthy weight – Exercise and following a balanced, healthy diet can help prevent obesity
- Controlling high blood pressure – Your doctor can check your blood pressure and, if your numbers are high, discuss methods of lowering them. These methods may include exercise and dietary changes.
- Avoiding exposure to chemicals at work - These could possibly increase the risk of kidney cancer
Trust NewYork-Presbyterian for Kidney Cancer Care
The experts at NewYork-Presbyterian provide high-quality, individualized care for each patient with kidney cancer. Our team of dedicated and compassionate specialists will work with you to develop a personalized treatment plan that provides you with the best chances for recovery.