Tumor lysis syndrome (TLS) is a rare but potentially fatal complication that can occur during cancer treatment. Doctors can treat TLS using a range of medications.

TLS happens when cancer cells break down and release chemicals into the bloodstream that the body filters out. If these substances build up, TLS may occur and can quickly become life threatening.

Healthcare professionals should monitor people undergoing cancer treatments to ensure they immediately receive treatment for TLS if it develops.

This article takes a closer look at TLS, including its symptoms, causes, risk factors, diagnosis, and treatment.

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Cancer treatment aims to destroy a person’s tumors. When the treatment damages and breaks down cancer cells, the cells release a number of chemicals into a person’s bloodstream through a process health experts call lysis.

Sometimes, cancer treatments can be so intense or work so quickly that the body is unable to keep up with filtering out the unwanted chemicals. This is when TLS occurs. TLS is the name for a group of health problems an individual may experience when they have a buildup of certain substances in the blood.

These health problems can include:

TLS often starts off with mild symptoms. These, however, may become severe if a person does not receive treatment, and the chemicals keep on building up in the blood.

Symptoms of TLS are usually the same as those of many other conditions, meaning they are nonspecific. The more the levels of certain substances in the blood depart from healthy ranges, the worse the symptoms may be.

Symptoms may include:

More severe symptoms that can occur as the chemicals accumulate in a person’s body may include:

If left untreated, TLS may lead to kidney failure and death.

Most often, TLS develops when a person is receiving chemotherapy or other cancer treatments.

TLS is more likely to occur during treatment for certain cancers, such as:

The condition usually develops during the first cycle of treatment but can also occur later on in therapy.

TLS symptoms typically develop about 48–72 hours after the initial treatment begins, but they can also appear within a few hours.

A number of factors can increase an individual’s risk of developing TLS. Before doctors start cancer treatment, they will look at a person’s risk of TLS to determine how best to proceed.

Risk factors include:

  • the type of cancer
  • the stage of the cancer
  • the size of the tumor
  • the pace at which the tumor grows
  • any preexisting conditions that may impact the organs affected by TLS
  • the type of cancer drug treatment a person receives

If an individual is at risk of developing TLS, doctors will request regular blood tests to monitor the levels of chemicals in the blood.

They may also order urine tests to check for signs that the kidneys are not working as effectively.

Tests may look at the levels of:

  • serum creatinine
  • blood urea nitrogen
  • sodium
  • potassium
  • calcium
  • phosphorous
  • lactate dehydrogenase
  • uric acid

Doctors use two sets of criteria to categorize TLS: the Cairo-Bishop and Howard criteria.

According to the Cairo-Bishop criteria, there is a 25% increase — in the case of calcium, a 25% decrease — of chemicals in the bloodstream from the baseline.

According to the Howard criteria, a person’s laboratory tests show two or more unusual results in 24 hours.

There are various medications that doctors may prescribe to manage TLS, including allopurinol, which prevents the body from making uric acid, and rasburicase, which breaks down uric acid in the body.

To prevent uric acid from forming crystals in the joints and causing gout, doctors may also prescribe acetazolamide.

More recent medications that doctors can use to treat TLS include B cell lymphoma-2 protein inhibitors and oral kinase inhibitors.

In some cases, however, medications may prove ineffective, and a doctor may decide that a person requires dialysis.

Dialysis replaces the function of the kidneys by removing waste products from the blood when the kidneys do not work effectively.

Not everyone who receives chemotherapy treatment develops TLS.

There are some steps healthcare professionals can take to minimize the likelihood of TLS occurring. For example, doctors can monitor people at medium and high risk of having TLS more closely.

Other preventive strategies may include:

  • monitoring closely fluid balance before chemotherapy
  • administering diuretics to improve urine output
  • monitoring closely potassium levels
  • administering medication to lower uric acid levels

If a person does not receive treatment quickly enough or at all, they may experience complications such as heart failure, kidney failure, and even death.

Other complications may include:

The outlook for individuals with TLS is typically good if healthcare professionals administer treatment promptly.

People usually recover from TLS, as doctors know which individuals are at high risk of developing this complication and generally monitor them already.

TLS is a rare complication that can occur during cancer treatment. However, it can be fatal in some cases, and therefore people should discuss the risks of TLS with a doctor and know what symptoms to look out for.

Individuals who develop TLS should start treatment as soon as possible to lower the risk of severe complications. Doctors can treat TLS using a range of medications.