Tumor lysis syndrome (TLS) is a common cause of acute kidney injury in patients with malignancies, and it is a frequent condition for which the nephrologist is consulted in the case of the hospitalized oncological patient. Recognizing the patients at risk of developing TLS is essential, and so is the prophylactic treatment. The initiation of treatment for TLS is a medical emergency that must be addressed in a multidisciplinary team (oncologist, nephrologist, critical care physician) in order to reduce the risk of death and that of chronic renal impairment. TLS can occur spontaneously in the case of high tumor burden or may be caused by the initiation of highly efficient anti-tumor therapies, such as chemotherapy, radiation therapy, dexamethasone, monoclonal antibodies, CAR-T therapy, or hematopoietic stem cell transplantation. It is caused by lysis of tumor cells and the release of cellular components in the circulation, resulting in electrolytes and metabolic disturbances that can lead to organ dysfunction and even death.
1. Introduction
Tumor lysis syndrome (TLS) is the result of a series of events leading to the rapid death of a high number of malignant cells. Lysis of these cells leads to the release of intracellular ions and metabolic byproducts into the bloodstream, resulting in hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia. All these disturbances may cause serious complications such as AKI, cardiac arrhythmias, seizures, and even death.
TLS is an oncological emergency with high morbidity and mortality, especially if the diagnosis is delayed and treatment measures are not instituted promptly
[1]. The most important aspect is to rapidly identify the patients at risk for TLS, in order to start the proper prophylactic and curative treatment. It commonly occurs in patients with high-grade hematological malignancies, such as acute leukemia and Burkitt’s lymphoma, but also in large and rapidly growing solid organ tumors, especially after starting chemotherapy
[2][3]. It is a life-threatening condition, being responsible for increasing the in-hospital mortality of the cancer patient by up to 79% in cases of acute myeloid leukemia (AML) during induction therapy
[4][5]. It may occur either spontaneously, or after antineoplastic therapy such as conventional chemotherapy, corticosteroids, molecular-targeted therapy, immunotherapy, and even after radiotherapy and chemoembolization
[6][7][8][9][10][11][12][13][14][15][16][17].
2. Definition and Classification
Hande and Garrow classified TLS in 1993 in two categories: laboratory and clinical TLS
[18]. They used some specific parameters of which variation are usually observed during the first four days after starting antineoplastic therapy. Their definition was not including patients with spontaneous TLS, and it was modified by Cairo and Bishop in 2004 by summing up the clinical and laboratory changes that appear within 3 to 7 days after the initiation of chemotherapy, thus including patients who already have TLS at presentation, as well as those who are developing it later on (
Table 1)
[19]. Additionally, it is necessary to exclude other causes of AKI.
Table 1. Cairo–Bishop criteria for defining tumor lysis syndrome (modified after
[19]).
Howard and colleagues made several amendments to the Cairo–Bishop definition in 2011:
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changes of the laboratory parameters must be simultaneous within 24 h because the patient may develop one abnormality, and later on another, unrelated to TLS (e.g., hypocalcemia associated with sepsis);
-
symptomatic hypocalcemia has to be a criterion for clinical TLS, even when the decrease in calcium level is less than 25% of baseline;
-
a 25% variation of a parameter is significant for the diagnosis only if it causes symptoms or if the value is not within the normal range
[2].
Cairo–Bishop Definition of Tumor Lysis Syndrome |
Melanoma |
Sarcoma |
Laboratory TLS = modification of at least 2 parameters within 24 h |
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|
5. Identification of Patients at Risk
TLS is associated with significant morbidity and mortality. Proper assessment of the patients with appropriate risk stratification is of major importance for a more efficient therapeutic approach. Several risk-stratification models for TLS have been developed
[28][29], most of them taking into account different patients’ characteristics (including other comorbidities) and type of neoplasia (
Table 3).
Table 3. Risk factors for tumor lysis syndrome
[5][30][31][32][33].
6.1. Prophylaxis
The key of prophylaxis is to maintain an adequate urine output and to decrease the blood levels of uric acid, potassium, and phosphate. The monitoring of biological values are recommended to be done with the following frequency:
In addition, it is recommended:
-
to avoid the nephrotoxic drugs (NSAIDs, contrast agents);
every 8 to 12 h for patients at intermediate risk;
-
to stop the treatment with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers.
The necessity for renal replacement therapy (RRT) decreased dramatically in the era of hypouricemic drugs, especially in the countries where rasburicase is available for the prevention and treatment of TLS. RRT is indicated when kidney dysfunction is aggravating despite therapeutic measures, when the patient develops hypervolemia, or when electrolyte disturbances are refractory to medical treatment.
The options for RRT are:
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daily hemodialysis;
-
continuous veno-venous hemofiltration;
daily for patients at low risk.
-
-
-
combination of intermittent hemodialysis and continuous hemofiltration/hemodiafiltration for an efficient clearance of phosphate, which is time dependent. These techniques use dialysis membranes with large pores, which allow for rapid clearance of molecules that otherwise are not efficiently removed by conventional hemodialysis.
Patient-Related Risk Factors |
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| Uric acid ≥ 8 mg/dL -
- -
-
Potassium ≥ 6 mg/dL
- -
-
Phosphate ≥ 4.5 mg/dL
|
Type of tumor |
|
Or 25% increase |
within 3 to 7 days after
|
Male gender | chemotherapy initiation |
- -
-
Calcium ≤ 7 mg/dL
|
Or 25% decrease |
Clinical TLS = laboratory TLS + 1 organ dysfunction or death |
- -
-
Renal dysfunction (creatinine > 1.5 X normal values)
- -
-
Cardiac involvement (arrhythmias)
- -
-
Neurological involvement (seizures, tetany)
- -
-
Death
|