Tumour lysis syndrome: too fast, too furious

Dr Romana Jassat explains tumour lysis syndrome and the treatment typically used to manage it.

Cancer therapies are evolving at a rapid pace. Modern therapies are now more powerful than ever before, targeting tumours with precision and often producing dramatic and impressive results. While we celebrate and marvel at the advancements in cancer care, we are often reminded of the double-edged nature of cancer therapy that physicians are faced with: the delicate balancing act between fighting cancer effectively and minimising the risk to those we treat.

Tumour lysis syndrome (TLS) is an anticipated but serious side effect of cancer treatment. It’s an oncological emergency that occurs when large numbers of cancer cells break down (usually at the start of therapy), releasing their cell contents into the bloodstream. Tumour lysis syndrome often develops quickly, hence early detection, monitoring, and instituting preventive measures are essential to prevent long-term consequences.

How exactly does it occur?

Cancer cells, much like all living cells, contain elements such as potassium, phosphate, nucleic acids, and uric acid. All cancer therapy is aimed at killing cancer cells. However, when this occurs rapidly, the surge of these substances flooding the bloodstream may overwhelm the body’s regulatory mechanisms and this can have serious and dramatic consequences. 

This is particularly true for haematological cancers, especially those that are high-grade (aggressive in nature), rapidly dividing (fast-growing cancers), and are known to be chemo-sensitive (known to quickly and effectively respond to a certain chemo regimen). Patients who have pre-existing kidney problems, the elderly, or those with large and bulky disease are known to be at risk for the development of tumour lysis syndrome.

What are the signs to watch out for?

Initial bloodstream abnormalities will be detected by your doctor on routine monitoring. These include metabolic derangements, such as an elevated potassium (hyperkalaemia), elevated phosphate (hyperphosphatemia), decreased calcium (hypocalcaemia), and an elevated uric acid level (hyperuricaemia). It’s important for your doctor to recognise these abnormalities on routine blood testing earlier rather than later, as these may serve as warning signs for what is to come.

What are the serious complications from TLS?

The cornerstone of tumour lysis syndrome treatment is early recognition by your healthcare provider. If some of the earlier signs are missed, this may result in serious consequences such as heart rhythm abnormalities (arrhythmias), seizures as well as the development of kidney failure. These complications can be avoided by being cognisant of the earlier bloodstream abnormalities (biochemical changes) which often precede the more serious clinical manifestations.

Prevention and management of TLS

A key element in the initiation of chemotherapy should include a formal assessment and evaluation to identify any potential risk factors for the development of tumour lysis syndrome. The subtype of cancer (high-grade lymphomas, Burkitt lymphoma or acute leukaemia) may also assist in this stratification. 

The adage prevention is better than cure still rings true in this setting, where aggressive hydration with fluids to flush out substances before they crystallise in the kidneys is essential. In addition, prompt management of elevated uric acid levels with appropriate drugs is equally important. Allopurinol and rasburicase are both used to control uric acid but have different mechanisms of action. Allopurinol prevents the formation of new uric acid while rasburicase breaks down existing uric acid into a substance that is easily eliminated by the kidneys. It’s also essential to notify a specialist renal physician earlier rather than later, should there be evidence of kidney damage as dialysis may be necessary in some circumstances.

Final thought

Tumour lysis syndrome reminds us that progress in cancer care comes with new and unique challenges. As therapies advance and become more effective, the ability to deal with the side effects and complications from these very therapies should also evolve. 

As healthcare professionals, we have a responsibility to our patients to anticipate, recognise, and manage these complications, and in so doing, provide holistic cancer care.

Dr Romana Jassat is a specialist physician and clinical haematologist who completed her training at the University of the Witwatersrand. She practices at Alberts Cellular Therapy (ACT), Pretoria East, and consults weekly at the ABJ Oncology practice in Vereeniging.

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