Bilateral kidney cancer refers to renal cancer that occurs in both kidneys. The condition may not cause any symptoms, but if they do occur, they may include bloody urine and flank pain.

There are several types of kidney cancer. Doctors classify them according to the type of cells in the kidney in which they start. In some cases, different types can occur simultaneously in both kidneys or develop in one and later in the other.

This article reviews what bilateral kidney cancer is, including its symptoms, causes, diagnosis, treatment, and outlook.

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Bilateral kidney cancer refers to cancer that occurs in both kidneys.

The American Cancer Society (ACS) highlights that renal cell carcinomas are the most common form of kidney cancer. However, bilateral kidney cancer is a relatively rare condition, accounting for only about 1 to 5% of all renal cell carcinomas, according to studies that research from 2016 cites.

The disease can occur spontaneously or in people with a genetic predisposition to developing kidney cancer.

Unilateral kidney cancer, which affects one kidney, and bilateral kidney cancer may cause the same symptoms.

However, many people with kidney cancer will not experience any symptoms in the early stages. In many cases, a person may not know they have the condition unless a doctor discovers a tumor during other examinations.

When symptoms occur, the most common may involve:

Other possible symptoms can include:

Symptoms may also develop in people whose cancer has metastasized, which means it has spread to other areas of the body. These symptoms can vary according to where the disease spreads.

The exact cause of kidney cancer remains unknown.

Bilateral kidney cancer can occur in several different types of renal cell carcinoma. This includes both clear cell carcinoma — the most common type of renal cell carcinoma — and papillary carcinoma, which may occur in both kidneys.

Approximately 4% of renal cell carcinomas occur due to an underlying genetic condition. Some of these conditions may cause bilateral kidney cancer. They include:

  • tuberous sclerosis syndrome
  • Von Hippel-Lindau syndrome
  • Birt-Hogg-Dubé syndrome
  • hereditary papillary carcinoma

According to a 2016 study, the following groups may have a higher risk of developing renal cell carcinoma:

  • African American, American Indian, and Alaska Native individuals
  • older adults
  • males
  • individuals with a family history of the condition
  • people who smoke cigarettes
  • anyone living with high blood pressure
  • people with obesity

If a doctor discovers a growth in the kidneys, they will likely order several tests, which can include:

Several people with kidney cancer develop paraneoplastic syndromes, which occur due to the immune system’s response to the tumors. They can affect several areas of the body, including the liver. A doctor may order additional testing to check for these syndromes.

Healthcare professionals may also order additional imaging tests. These can help identify both tumors and help with staging. They may include:

Treatment depends on the stage of cancer at diagnosis.

In the early stages, doctors typically recommend partial or radical nephrectomy, which involves removing some or all the kidney tissue.

In the more advanced stages, healthcare professionals may recommend surgical removal of the tumor and systemic targeted molecular therapies to treat cancer that spreads to other areas of the body.

Bilateral kidney cancer involves similar treatments that can include partial or radical nephrectomies. Studies show that many people with bilateral kidney cancer benefit from partial nephrectomies.

The overall outlook for most people with kidney cancer is relatively positive.

Doctors and other experts often describe outlook in terms of 5- or 10-year survival rates. These numbers represent the percentage of people who are still alive 5 or 10 years following their initial diagnosis.

Though helpful for understanding or explaining outlook, these rates cannot predict how well a person will respond to treatment or their likelihood of survival. A variety of factors, such as age, stage of cancer, and overall health, can all influence a person’s survival and outlook.

According to the National Cancer Institute, the 5-year survival rates for kidney cancers between 2013 and 2019 are:

  • local: 92.9%
  • regional, which involves tissue or lymph nodes outside of kidneys: 73.8%
  • distant, which means cancer has spread to other areas of the body: 17.4%

These statistics do not separate unilateral and bilateral kidney cancer. However, survival rates for bilateral kidney cancer may be similar, according to a 2020 study.

Researchers found evidence that suggests that both cancer-specific and overall survival rates following bilateral and unilateral kidney cancer are similar. They found that factors affecting the likelihood of survival included a person’s age and the size and grade of the tumor.

Bilateral kidney cancer is a relatively uncommon occurrence. Bilateral means that both kidneys develop tumors.

Genetics may play a role in bilateral kidney cancer, as people with certain genetic conditions are more likely to develop it.

However, bilateral kidney cancer symptoms, treatment options, and a person’s outlook do not vary much, if at all, from unilateral kidney cancer cases. A person may not experience any symptoms in the early stages of bilateral kidney cancer. However, symptoms may include flank pain and blood in the urine.

Treatment typically involves surgery in which a healthcare professional removes part or all of the kidney. However, doctors may also recommend targeted therapies.

Tumor size and grade and a person’s age often affect their outlook. For example, people with early stages of bilateral kidney cancer have a better overall survival rate compared to those with more advanced stages.