The kidneys are vital organs involved in blood filtering and urine production. Renal cell carcinoma is the most common type of kidney cancer.

Renal cell carcinoma accounts for about 90% of all kidney cancer cases. It occurs when cells in the tubules of the kidneys start to grow out of control. The tubules are tube-like structures that return important substances to the blood and remove waste products.

In most cases, a person will develop a single tumor in one kidney. In other cases, they may develop 2 or more tumors in one or both of their kidneys at the same time.

The following article describes the causes, symptoms, treatment, and outlook for renal cell carcinoma.

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Renal cell carcinoma is sometimes called renal cell cancer and has several subtypes. They include:

  • Clear cell: Accounts for about 75% of all renal cell cancers. In this type, the cells appear clear under a microscope.
  • Papillary: Accounts for about 10% of all renal cell cancers. In this type, the tumors appear to have finger-like shapes coming from them.
  • Chromophobe: Accounts for about 5% of all cases. In this type, the cells are generally clear or pale but are larger and distinct from clear cell.
  • Other subtypes: In addition to the above, there are several much less common subtypes with unique characteristics.

Whether treatment is successful depends on several factors, including the stage of the cancer at diagnosis and a person’s overall health.

Like other cancers, doctors assign renal cell carcinoma to one of four stages. As a general rule, lower numbers indicate smaller tumors and limited spread.

According to the American Cancer Society, staging for renal cancer can be somewhat complex and confusing. In most cases, doctors use the American Joint Committee on Cancer’s TNM system to stage renal cancer. It bases staging on the following:

  • T: Stands for tumor size and if there is spread to nearby areas.
  • N: Stands for lymph nodes and indicates whether the cancer has spread to one or more nearby lymph nodes.
  • M: Stands for metastasized and indicates whether the cancer has spread to distant areas of the body.

In most cases, the stages align as follows:

  • Stage I: Tumor is less than 7 centimeters (cm) and has not spread to lymph nodes or distant areas. People can further divide this into stage 1a for tumors 4 cm or smaller and 1b for tumors 4–7 cm.
  • Stage II: Tumor is 7 cm or larger but has not spread to the lymph nodes or distant areas.
  • Stage III: Tumor is growing into one of the major veins in the kidney but has not spread to distant areas or the lymph nodes. Alternatively, it may be any size, may be outside the kidney, has not spread to Gerota’s fascia, and has spread to a nearby lymph node with no distant spreading.
  • Stage IV: Tumor has grown beyond Gerota’s fascia and may be growing into the adrenal gland. It may or may not have spread to a local lymph node but not to distant lymph nodes or other organs. Stage IV can also include tumors of any size that may be growing outside the kidney, may or may not have spread to nearby lymph nodes, but have spread to distant lymph nodes and/or other organs.

Though researchers are aware of several risk factors for kidney cancer, they do not fully understand how the factors affect cell mutation.

They do know, however, that kidney cancer occurs due to changes in the DNA of kidney cells. The changes cause the cells to grow out of control. According to the American Cancer Society, there are two types of gene mutation that can occur.

Inherited gene mutations are a known risk factor for developing kidney cancer. This This can occur when a parent or other close relative has a gene that mutates and causes kidney cancer, then passes that gene on to an offspring.

Acquired gene mutation occurs when a person comes in contact with cancer-causing agents that may alter their cells’ DNA.

Some risk factors that can increase a person’s likelihood of developing renal cancer include:

  • being overweight
  • smoking
  • family history of certain conditions such as von Hippel-Lindau disease or hereditary papillary renal cell carcinoma
  • high blood pressure
  • family history of renal cancer
  • misuse of over-the-counter (OTC) pain medications for a long period of time

A person may not notice early signs or symptoms of renal cancer, and some symptoms are similar to those of other conditions.

A person should talk to their doctor about the following symptoms because they may be signs of renal cancer or other conditions that affect the kidneys:

  • anemia
  • lump in abdomen
  • bloody urine
  • suppressed appetite
  • weight loss for no reason
  • pain on either side that does not stop or lessen

When discussing the outlook for kidney cancer, most doctors base prognosis on 5-year survival rates among other people who are living with the same cancer and stage.

The survival rate refers to the proportion of people who are still alive for a length of time after receiving a particular diagnosis. For example, a 5-year survival rate of 50% means that 50%, or half, of the people are still alive 5 years after receiving the diagnosis.

It is important to remember that these figures are estimates and are based on the results of previous studies or treatments. A person can talk with a healthcare professional about how their condition is going to affect them.

According to the American Cancer Society, the 5-year outlook for people living with renal cancer is as follows:

  • Localized: Cancer has not spread, 93% survival rate.
  • Regional: Cancer has spread to nearby lymph nodes,70% survival rate
  • Distant: Cancer has spread to other areas of the body, 13% survival rate
  • Combined survival rate: takes into account all three levels, 75% survival rate

According to an article published in American Family Physician, a contrast-enhanced, triple-phase helical CT scan is the best way to examine a mass or lump in the kidneys. Researchers note that a doctor may also find a mass during an unrelated examination.

Other ways doctors can diagnose or detect signs of renal cell carcinoma include:

  • review of symptoms and family history
  • urine tests
  • blood tests
  • other imaging tests such as MRIs, x-rays, ultrasounds, or bone scans
  • biopsy of the kidney

Treatment depends on a person’s age and overall health, the subtype of cancer, the stage of cancer, and how the cancer has responded to other treatments. A doctor will also take into account a person’s treatment preferences.

The National Cancer Institute notes that standard treatments for renal cell cancer typically include:

  • Radiation therapy: Uses radiation to kill cancer cells.
  • Surgery: Involves removal of part or all of the kidney.
  • Targeted therapy: Uses medication to target cancer cells while ignoring healthy cells.
  • Chemotherapy: Medication that stops cells from growing or multiplying.
  • Immunotherapy: Teaches the body’s immune system to attack cancer cells.

In addition to the current standards, researchers continue to look for new therapies and ways to improve on existing therapies. People may want to talk to their doctor about joining a clinical study researching new ways to treat renal cancer.

A person may also find that certain lifestyle changes may help them with managing the symptoms related to the cancer or treatment side effects. Eating a healthy diet, exercising, and using relaxation techniques may be helpful for some people.

Renal cell carcinoma is the most common type of kidney cancer, with an overall 5-year survival rate of 75%. Risk factors can include smoking, being overweight, and having a family history of kidney cancer.

There are currently several treatments that can help manage this type of cancer, and more that researchers are studying. A person should talk to their doctor if they suspect they have renal cancer.