Select Oncological Emergencies and Bone Metastases Flashcards
What is tumor lysis syndrome
Rapid breakdown of cancer cells releases intracellular contents, contents are released too quickly for the body to remove them, causing metabolic abnormalities
What changes happen to electrolytes and other contents due to tumor lysis syndrome
Increased uric acid, increased potassium, increased phosphate, decreased calcium
What type of cancer origins are most likley to have tumor lysis syndrome
Hematological malignancies: lymphoma and leukemia
What are complications of TLS and what causes them
Hyperkalemia: release of intracellular potassium
Acute Renal Failure: DNA coverted to and end product of uric acid crystallize in the kidney, High phosphorous precipitates with calcium
What are the two types of ways TLS is categorized
Laboratory and clinical
What are the lab values signifying TLS
Uric acid: greater than 8 mg/dL
Potassium: greater than 6 mEq/dL
Phosphorous: greater than 4.5 mg/dL
Calcium: less than 7 mg/dL
T/F: Besides the distinct laboratory values a 50% increase in baseline uric acid, potasssium and phosphorous with a 50% decrease in calcium can also identify TLS
False: A 25% increase in uric acid, phosphorous, and potassium and a 25% decrease in calcium can also determine if TLS is present
What is the key fact for defining TLS
GREATER THAN OR EQUAL TO 2 of the metabolic abnormalities within 3 DAYS BEFORE OR 7 DAYS AFTER INITIATION of treatment
What is clinical TLS
Laboratory TLS with any of the following:
Creatinine greater than 1.5 the upper limit. cardiac arrhythmia, seizure, sudden death
What is the prime enzyme for converting DNA to uric acid, what pH does the urine need to be to remove the uric acid
Xanthine oxidase, 5
What are cancer related risk factors for TLS
Bulky tumors (large tumor mass, organ infiltration, bone marrow involvement), High LDH, Chemosensitive Tumors (Burkitt lymphoma, lymphoblastic lymphoma, acute leukemias)
What are patient related risk factors for TLS
Gout, chronic renal insufficiency, hypertension
What is the patient presentation for TLS
Hyperuricemia, dehydration, diminished urine output, acute renal insufficiency, acidic urine
What drug can inhibit xanthine oxidase, when is it used
Allopurinol, used in prophylaxis setting at initiation of chemotherapy in high tumor burden malignancies
How is allopurinol doses, when is it given and continued
Using BSA: 300 mg/m2/d for a max of 800mg/day, give 1-2 days prior to induction chemotherapy, continue 3-7 days after chemotherapy until normalization of lab TLS
Drug interactions to allopurinol
meraptopurine, thiazide diuretics, and antibiotics
What is rasburicase
recombinant urate oxidase, catalyzes oxidation of urate into allantoin (highly soluble with good urinary excretion)
How does rasburicase effect uric acid, what is a key BBW
Uric acid levels decrease within 4 hours of administration, G6PD deficiency
What is a key fact about rasburicase and its effect on uric acid measurement at room temperature, how can this be avoided
Enzymatically degrades uric acid in blood samples left at room temperature/ collect blood samples in pre-chilled tubes containing heparin, immediately immerse and maintain sample in an ice water bath, assay plamsa samples with 4 hours of collection
What is dosing for rasburicase
0.2 mg/kg daily for 5 days OR 3 to 7.5 mg for one dose
T/F: When TLS has been identified hydration with normal saline at 125 ml/hr should be started ASAP before chemotherapy
True
What are the two go to options for treating hypercalcermia
Normal saline and calcitonin (antagonist of the parathyroid hormone)
Which class of drugs that prevent breakdown of bine are used in hypercalcemia of malignancy (HOM)
IV Bisphosphaonates: Pamidronate and Zoledronic acid
What is a mild case HOM, Moderate, severe
10.5-12, 12-14, Greater than 14
T/F: If a patient has HOM what do they all recieve
Fluids for 6 hours then rechecked calcium
What dose of zoledronic acid should be given for HOM
Zoldronic acid 4mg IV once
Which drug is used as a last resort, why
Calcitonin, very expensive
Which cancers are most common to metastasize to bone
Breast, Lung, Thyroid, Kidney, Prostate, multiple myeloma and lymphoma
How are bone metastasize characterized
Osteolytic or osteoblastic
What medications are osteoclast inhibitors
bisphonates and denosumab
What is the dosing of pamidrone
60-90 mg IVPB administered over two hours
What is the dosing for zolendronic acid
3-4 mg IVPB administrered over 15 minutes
What is the MOA of denosumab, how is it dosed for treating of bone metastases, HOM
120 mg SC every 4 weeks (supplement)/ 120 mg SC every 4 weeks during the first month, give an addition 120 mg on days 8 and 15
What are notable adverse reaction of denosumab
Osteonecrosis of the jaw, hypocalcemia. PTH levels increase when the patient has severe renal impairment (CrCl less than 30 or is on dialysis)
What are the bone-targeted radiopharmaceutical therapies
Radium -223, Samarium 153 lexidronam (153 Sm), Strontium- 89 (89Sr)
What is the MOA of Radium 223, what type of cancer is it used in
Mimics calcium to form complexes with bone mineral in areas with increased bone runover, alpha emission casued DS DNA breaks resulting in antitumor effect
What are the warning of using Radium 223
Myelosuppression, dehydration, secondary malignancies
