Tumour lysis syndrome

When cancer cells break down and die, they release substances into the blood. If cancer cells break down so quickly that the kidneys can’t remove these substances from the blood, it can lead to tumour lysis syndrome (TLS). TLS is a group of problems with blood levels, including high levels of uric acid (hyperuricemia), potassium (hyperkalemia) and phosphate (hyperphosphatemia), and low levels of calcium (hypocalcemia).

TLS is a potentially life-threatening problem and needs to be treated right away. If it is not controlled, abnormal blood levels can cause a variety of problems. Uric acid can be deposited in the joints, causing a painful gout-like condition. A buildup of uric acid in the kidneys can cause damage and stones to form. High phosphate levels can also damage the kidneys and lead to kidney failure. Abnormal levels of potassium and calcium can affect heart rhythm and lead to neurological changes such as weakness, irritability and confusion.

TLS is more likely to develop when certain cancers or blood disorders are treated with chemotherapy. These cancers cause a high white blood cell count, have a high tumour burden or have rapidly dividing cells that respond well to treatment. These include:

• acute leukemia
• aggressive non-Hodgkin lymphoma
• myeloproliferative disorders
• solid tumours such as hepatoblastoma and stage IV neuroblastoma
• cancers that cause poor kidney function before treatment starts

Tumour lysis syndrome usually occurs at the start of chemotherapy when a large number of tumour cells are destroyed. It can occur within a few hours of treatment, but it is most often seen 48–72 hours (2–3 days) after treatment starts.

TLS is not limited to systemic chemotherapy, which travels throughout the body to destroy cancer cells. It can also occur with intrathecal chemotherapy, which is given directly into the fluid-filled space around the brain and spinal cord. TLS can develop after chemoembolization, which is a procedure that stops blood flow to a tumour and delivers chemotherapy directly to the tumour.

TLS has been linked with other treatments, including radiation therapy, corticosteroids, targeted therapy, hormonal therapy and biological therapy.

Symptoms of tumour lysis syndrome may be mild at first. They get worse as the levels of abnormal substances in the blood increase. Symptoms of TLS include:

• nausea
• vomiting
• diarrhea
• muscle cramps or twitches
• weakness
• numbness or tingling
• fatigue
• decreased urination
• irregular heart rate
• confusion
• restlessness
• irritability
• delirium
• hallucinations
• seizures

Report symptoms to your doctor or healthcare team as soon as possible.

Tumour lysis syndrome is usually diagnosed by:

• complete blood count (CBC)
• blood chemistry and uric acid levels in the blood
• urinalysis

Find out more about these tests and procedures.

Before treatment begins, your healthcare team will determine if you have a risk of developing tumour lysis syndrome. The risk is based on:

• the type of cancer
• how far the cancer has progressed
• pre-existing conditions, such as poor kidney function, heart disease or high blood pressure
• lab tests

If you have a risk of developing TLS, your healthcare team can suggest ways to prevent it before you start cancer treatment. This usually includes making sure your body gets enough fluids. You may be given fluids through a needle in a vein, or intravenously. Fluids are usually given 24–48 hours before treatment starts and for several days after treatment is finished. While you are given fluids, the healthcare team will monitor how much urine you produce (urine output). It is important that you output 150–200 ml of urine every hour. They may prescribe a diuretic to maintain urine flow. Diuretics are drugs that help the body make urine.

Your healthcare team will do blood tests and watch for symptoms of TLS throughout treatment. If TLS develops, they may suggest the following measures to treat it.

You may be given a medicine to lower the level of uric acid in your body. Allopurinol (Zyloprim) is a drug that stops the body from making uric acid. Rasburicase (Fasturtec) is a drug that breaks down uric acid so that the body can get rid of it.

You may also be given drugs to stop uric acid from forming crystals. This makes it easier for the kidneys to remove uric acid from the body. You may be given sodium bicarbonate or acetazolamide (Diamox) with the intravenous fluids. You don’t need to take this drug if you receive rasburicase.

You may need to have dialysis if TLS can’t be corrected or if kidney failure worsens. Dialysis removes wastes from the blood when the kidneys don’t work properly.