What is tumor lysis syndrome and which cancers are at highest risk?

• A. Slow tumor destruction with no metabolic disturbances; solid tumors
• B. Rapid release of intracellular contents causing hyperkalemia, hyperphosphatemia, hyperuricemia, hypocalcemia; high-risk in bulky or rapidly proliferating leukemias/lymphomas
• C. Autoimmune destruction of platelets
• D. Hypocalcemia due to bone metastases

Answer: (B)

Tumor lysis syndrome happens when a large number of tumor cells are destroyed rapidly, releasing their contents into the bloodstream. This sudden release leads to metabolic and electrolyte disturbances: high potassium, high phosphate, high uric acid, and low calcium. The uric acid and calcium phosphate can accumulate in the kidneys, risking acute kidney injury, especially if there isn’t enough time to clear these substances.

The cancers at highest risk are those with a high tumor burden and very rapid cell turnover, particularly bulky or fast-growing leukemias and lymphomas. This includes high-grade lymphomas (such as Burkitt lymphoma) and acute leukemias, where a lot of cells can be lysed quickly, especially after starting therapy or sometimes spontaneously.

The other descriptions don’t fit TLS: a slow tumor destruction with no metabolic disturbances doesn’t involve the dangerous electrolyte shifts TLS causes; autoimmune destruction of platelets is a different syndrome (immune thrombocytopenia); hypocalcemia from bone metastases is a separate mechanism and not the acute, rapid cell breakdown seen in TLS.