Lecture 18 - Oncologic Emergencies Flashcards
Oncologic emergency
potentially morbid or life-threatening events directly or indirectly related to a patient’s tumor or its treament
can occur at any time during a malignancy, from the presenting sx to end-stage disease
Examples of oncologic emergencies
metabolic, neurologic, cardiovascular, pulmonary, infectious
Metabolic
hypercalcemia of malignancy (HCM)
tumor lysis syndrome (TLS)
Neurologic
spinal cord compression
Cardiovascular
superior vena cava syndrome (SVC)
malignant pericardial effusion
cardiac tamponade
Pulmonary
pleural effusions
Infectious
neutropenic fever
Tumor lysis syndrome (TLS)
constellation of metabolic derangements resulting from death of malignant cells - massive release of intracellular contents into bloodstream that overwhelms the body’s homeostasis
serious and life-threatening
TLS risk factors
tumor specific risk factors: high tumor burden, high tumor grade with rapid cell turnover, and treatment sensitive tumors
pt specific risk factors: age, preexisting renal impairment, concomitant use of drug known to increase uric acid (aspirin, alcohol, thiazide diuretics, caffeine)
TLS pathophysiology
hyperkalemia, exacerbated by AKI
hyperuricemia - catabolism of nucleic acids, poor solubility in urine = uric acid crystal precipitation in renal tubules –> AKI
hyperphosphatemia - excess phosphate binds to calcium and crystalize –> deposits into tissues, exacerbates AKI
hypocalcemia
Acute renal failure
48-72 hours after initiation of therapy
sx: oliguria, N/V, lethargy, fluid overload, edema, CHF, seizures
TLS: principles of management
prevention and immediate management is key
management of acute TLS: identify high risk pts - proactively institute aggressive prophylactic strategies to prevent and/or reduce the severity of TLS; monitor electrolytes; aggressive hydration - enhances urine flow, promotes uric acid and phosphate excretion; control of hyperuricemia - with uric acid lowering drugs
Low risk prophylaxis
monitoring, hydration, +/- allopurinol
Intermediate risk prophylaxis
monitoring, hydration, allopurinol
High risk prophylaxis
monitoring, hydration, rasburicase
Aggressive hydration
fluids and hydration: improves intravascular volume, renal perfusion, and glomerular filtration
decreases risk of life-threatening hyperkalemia
maintain urine output = 80-100 mL/m^2/hr
always consider cardiac function when assessing fluid rate and volume!
Hyperuricemia
uric acid + xanthine are both potentially nephrotoxic –> freely filtered at glomerulus; becomes overwhelmed = crystalizes within tubular lumen, causes direct tubular injury = AKI
humans lack a functional gene for urate oxidase –> further metabolizes uric acid to freely soluble and excretable allantoin
Allopurinol medical management
allopurinol is converted to oxypurinol which inhibits the conversion of xanthine to uric acid, decreases generation of uric acid
only prevents formation of new uric acid, does not facilitate breakdown of uric acid already produced
reduces risk of obstructive uropathy
renal adjustment for CrCl < 20
Allopurinol limitations
doesn’t reduced already formed uric acid, may take several days to lower uric acid, decreases clearance of certain chemos - 6-MP, azathioprine, high-dose methotrexate
Rasburicase
recombinant urate oxidase that catalyzes the oxidation of uric acid into soluble metabolite, allantoin
decreases uric acid levels, including already formed uric acid