Kidney Tumors and Kidney Cancer

Kidney tumors (also called renal tumors) are growths in the kidneys that can be benign or cancerous. Most do not cause symptoms and are discovered unexpectedly when you are being diagnosed and treated for another condition.

Kidney Tumor Overview and Symptoms

The kidneys are organs in the abdomen that remove waste and extra water from the blood (as urine), and help keep chemicals (such as sodium, potassium and calcium) balanced in the body. The kidneys also make hormones that help control blood pressure and stimulate bone marrow to make red blood cells.

Types of benign kidney tumors include:
  • Renal adenoma – Renal adenomas are the most common form of benign, solid kidney tumor, and are typically small, low-grade growths. Their cause is unknown.
  • Renal oncocytoma – Oncocytoma is a benign, usually asymptomatic tumor that can grow quite large. They can develop throughout the body and are not unique to the kidneys. Their cause is also unknown, and they appear with greater frequency in men than in women.
  • Angiomyolipoma – Also known as renal hamartoma, angiomyolipomas are rare, benign tumors that can be caused by an inherited genetic mutation. They can occur on an isolated, individual basis, but most often are associated with a rare genetic disease called tuberous sclerosis, which can cause tumors in the skin, kidneys, brain and other organ systems. In patients without tuberous sclerosis, these tumors most often occur in middle-aged women.
  • Fibroma – Fibromas are tumors of the fibrous tissue on, in or surrounding the kidney. They are rare and more common in women. Their cause is unknown and most do not cause symptoms.
  • Lipoma – Lipomas are rare renal tumors originating in the fat cells within the renal capsule or surrounding tissue. Lipomas typically occur in middle-aged women.
What is Kidney Cancer?

If a kidney tumor is malignant, it is kidney cancer. The two main types of kidney cancer are renal cell cancer and transitional cell cancer. In adults, renal cell cancer, which begins in the lining of small tubes inside the kidney, is most common. Transitional cell cancer is far less common. Wilms’ tumor, another type of kidney cancer, is most frequently seen in children.

Kidney cancer symptoms may include:
  • Blood in the urine
  • Pain or a lump in the lower back
  • Fatigue)
  • Loss of appetite
  • Unexpected weight loss
  • Fever
  • Anemia
Kidney cancer diagnostic tests may include:
  • Urine tests: Using a urine sample from normal urination, clinicians will determine if the urine contains tumor cells.
  • Cystoscopy: allows the doctor to see inside the body with a thin, lighted, flexible tube called a cystoscope
  • Biopsy: the removal of a small amount of tissue for examination under a microscope
  • Computed tomography (CT or CAT) scan: creates a 3-dimensional picture of the inside of the body using x-rays taken from different angles
  • Magnetic resonance imaging (MRI): uses magnetic fields, not x-rays, to produce detailed images of the body
  • Positron emission tomography (PET) scan: creates pictures of organs and tissues inside the body
  • Ultrasound: uses sound waves to create a picture of the internal organs
  • Blood tests: to check for increased blood levels of certain proteins


Surgery for Kidney Tumors and Kidney Cancer

Surgery is generally the first line treatment for benign kidney tumors or kidney cancer that has not spread. Laparoscopic surgery allows for a minimally invasive operation, with the surgeon making small incisions in the abdomen to insert a small light, camera and other instruments used to view and remove the tumor. It has been shown that laparoscopic surgery is as effective as traditional surgery and makes for an easier recovery.

Active Surveillance for Smaller Kidney Tumors

Our kidney tumor surgeons have extensive experience and are among the world’s leading experts in minimally invasive surgical removal of smaller kidney tumors (robotic partial nephrectomy). However, our published studies have shown that very few of these carefully selected tumors ever need to be removed. In these select patients, we carefully monitor the tumor for growth over time. This is called “active surveillance” or "watchful waiting."

The decision to pursue active surveillance depends on a number of factors, including

  • Patient age
  • Overall patient health
  • Size of tumor on imaging (CT, MRI or ultrasound)
  • Growth rate of tumor over time

Here at BIDMC, we have teamed up with researchers from Johns Hopkins to study the growth rate of these tumors and have developed a scoring system to help determine whether a patient is a candidate for this active surveillance program. Together with our colleagues at Johns Hopkins, we have one of the world's largest databases of kidney tumors followed over time without surgery. Ask one of our kidney tumor experts about your score and to see if you qualify for active surveillance.


Immunotherapy, also called biologic therapy, is a type of cancer treatment designed to boost the body's natural defenses to fight cancer. It uses materials either made by the body or in a laboratory to improve, target or restore immune system function. It may work in one of the following ways:

  • Stopping or slowing the growth of cancer cells
  • Stopping cancer from spreading to other parts of the body
  • Helping the immune system work better at destroying cancer cells
Monoclonal Antibodies

Antibodies are proteins made by your immune system to help fight infections. Man-made versions, called monoclonal antibodies (mAbs), can be designed to attack a specific target. When a monoclonal antibody attaches to a cancer cell, it may allow the immune system to destroy the cancer cell, prevent cancer cells from growing rapidly and carry drugs directly to cancer cells.

Monoclonal antibodies currently approved by the US Food and Drug Administration (FDA) to treat cancer include:

  • Alemtuzumab (Campath)
  • Bevacizumab (Avastin)
  • Cetuximab (Erbitux)
  • Ipilimumab (Yervoy)
  • Nivolumab (Opdivo)
  • Ofatumumab (Arzerra)
  • Panitumumab (Vectibix)
  • Pembrolizumab (Keytruda)
  • Rituximab (Rituxan)
  • Trastuzumab (Herceptin)
Cytokine Based Immunotherapy

Non-specific immunotherapies also help the immune system destroy cancer cells. Cytokines are a category of small proteins that are important in cell signaling. They are released by cells and affect the behavior of other cells. They are especially important in the immune system; cytokines modulate the balance between humoral and cell-based immune responses and regulate the maturation, growth and responsiveness of particular cell populations. They are important in health and disease, specifically in host responses to infection, immune responses, inflammation, trauma, sepsis, cancer and reproduction.

Two common cytokine immunotherapies are:

  • Interleukins help the immune system produce cells that destroy cancer. An interleukin made in a laboratory, called interleukin-2, IL-2 or aldesleukin (Proleukin), is used to treat kidney cancer and skin cancer, including melanoma.
  • Interferons help the immune system fight cancer and may slow the growth of cancer cells. An interferon made in a laboratory, called interferon alpha (Roferon-A [2a], Intron A [2b], Alferon [2a]), is the most common type of interferon used in cancer treatment.
Cancer Vaccines

A vaccine is another method used to help the body fight disease. A treatment vaccine helps the body's immune system fight cancer by training it to recognize and destroy cancer cells. It may be given to try to prevent cancer from coming back, eliminate any remaining cancer cells after other types of treatment or stop cancer cell growth. A treatment vaccine is designed to be specific, which means it should target the cancerous cells without affecting healthy cells. At this time, cancer vaccines are largely experimental and not proven to be effective.

Kidney Tumor Program

As the only clinic in Boston to focus exclusively on kidney cancer, we offer individuals with renal tumors the highest level of medical care and coordinated services available.

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Procedures for Kidney Problems

Our urology and nephrology specialists provide advanced surgical options for patients with all types of kidney conditions, including benign and malignant kidney tumors. 

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