Pocket Medicine: The Massachusetts General Hospital Handbook of Internal Medicine (81 page)

• Unknown source: continue antibiotics until afebrile
and
ANC >500 cells/µL

• Less clear when to d/c abx when Pt is afebrile but prolonged neutropenia

Role of hematopoietic growth factors
(
NEJM
2013;368:1131)

• Granulocyte (G-CSF) and granulocyte-macrophage (GM-CSF) colony-stimulating factors can be used as 1° prophylaxis when expected FN incidence >20% or as 2° prophylaxis after FN has occurred in a previous cycle (to maintain dose-intensity for curable tumors). CSFs ↓ rate of FN but have not been shown to impact mortality.

• Colony-stimulating factors can be considered as adjuvant therapy in high-risk FN Pts

SPINAL CORD COMPRESSION

Clinical manifestations
(
Lancet Neuro
2008;7:459)
• Metastases located in vertebral body extend and cause epidural spinal cord compression •
Prostate
,
breast
and
lung
cancers are the most common causes, followed by renal cell

carcinoma, NHL and myeloma

•
Site of involvement
:
thoracic
(60%), lumbar (25%), cervical (15%) • Signs and symptoms:
pain
(>95%,
precedes neuro
D
s
),
weakness
,
autonomic dysfunction
(urinary retention, ↓ anal sphincter tone),
sensory loss
Diagnostic evaluation

• Always take back pain in Pts with solid tumors very seriously • Do
not
wait for neurologic signs to develop before initiating evaluation b/c duration & severity of neurologic dysfunction before Rx are best predictors of neurologic outcome • Urgent
whole-spine MRI
(Se 93%, Sp 97%); CT myelogram if unable to get MRI
Treatment

•
Dexamethasone
(10 mg IV × 1 stat, then 4 mg IV or PO q6h)

initiate immediately
while awaiting imaging if back pain + neurologic deficits

• Emergent RT or surgical decompression if confirmed compression/neuro deficits • Surgery + RT superior to RT alone for neuro recovery in solid tumors (
Lancet
2005;366:643) • If pathologic fracture causing compression → surgery; if not surgical candidate → RT

TUMOR LYSIS SYNDROME

Clinical manifestations
(
NEJM
2011;364:1844;
BJH
2010;149:578)
• Large tumor burden or a rapidly proliferating tumor → spontaneous or chemotherapy-induced release of intracellular electrolytes and nucleic acids • Most common w/ Rx of high-grade lymphomas (
Burkitt’s
) and leukemias (
ALL
,
AML
,
CML in blast crisis
); rare with solid tumors; rarely due to spontaneous necrosis • Electrolyte abnormalities: ↑ K, ↑ uric acid, ↑ PO
₄
→ ↓ Ca •
Renal failure
(urate nephropathy)
Prophylaxis

• Allopurinol 300 mg qd to bid PO or 200–400 mg/m
²
IV (adjusted for renal fxn) & aggressive hydration prior to beginning chemotherapy or RT

• Rasburicase (recombinant urate oxidase) 0.15 mg/kg or 6 mg fixed dose (except in obese Pts) & aggressive hydration prior to beginning chemotherapy or RT (see below)
Treatment

•
Avoid
IV contrast and NSAIDs • Allopurinol + aggressive IV hydration ± diuretics to ↑ UOP

• Consider alkalinization of urine w/ isotonic NaHCO
₃
to ↑ UA solubility & ↓ risk of urate nephropathy (controversial: may cause metabolic alkalosis or Ca
₃
(PO4)
₂
precipitation) • Rasburicase (0.1–0.2 mg/kg × 1, repeat as indicated) for ↑↑ UA, esp. in aggressive malig; UA level must be drawn on ice to quench
ex vivo
enzyme activity (
JCO
2003;21:4402;
Acta Haematol
2006;115:35). Avoid in G6PD deficiency as results in hemolytic anemia.

• Treat hyperkalemia, hyperphosphatemia and symptomatic hypocalcemia • Hemodialysis may be necessary; early renal consultation for Pts w/ renal insuffic. or ARF

CANCER OF UNKNOWN PRIMARY SITE

• Bony mets: common primary tumors include breast, lung, thyroid, kidney, prostate

NOTES

PNEUMONIA

Clinical manifestations

• “Typical”: acute onset of fever, cough w/ purulent sputum, dyspnea, consolidation on CXR

• “Atypical” (originally described as cx
): insidious onset of dry cough, extrapulm sx (N/V, diarrhea, headache, myalgias, sore throat), patchy interstitial pattern on CXR

• S/s & imaging do
not
reliably distinguish between “typical” (
S. pneumo
,
H. flu
) and “atypical” (
Mycoplasma
,
Chlamydia, Legionella
, viral); ↑ aminotransferases & ↓ Na w/
Legionella
Diagnostic studies

•
Sputum Gram stain
: utility debated. Good sample (ie, sputum not spit) has <10 squamous cells/lpf. Purulent sample has >25 PMNs/lpf.

•
Sputum bacterial culture
: transport to lab w/in 1–2 h of collection • Blood cultures (
before antibiotics!
):
in ~10% of inPts, depending on pathogen •
CXR
(PA & lateral; see Radiology inserts) → tap effusions if >5 cm or severe PNA • Other:
S
_a
O
₂
or P
_a
O
₂
, arterial pH (if severe), CBC w/ diff, Chem-20; HIV test (if unknown) • Other micro based on clinical suspicion (paired serologies available for most atypicals):

Mycoplasma
: PCR of throat or sputum/BAL
before
first dose abx

Legionella
urinary Ag (detects
L. pneumophila
L1 serotype, 60–70% of clinical disease)

S. pneumoniae
urinary Ag (Se 50–80%, Sp >90%)

MTb: induced sputum for AFB stain and mycobacterial cx (
empiric respiratory isolation while pending
); avoid quinolones if suspect TB; request rapid DNA probe if stain

Induced sputum for PCP if HIV
or known ↓ cell-mediated immunity

• Viral testing (DFA or PCR) on nasopharyngeal swab or sputum; rarely viral cx • Bronchoscopy: consider if immunosupp., critically ill, failing to respond, or chronic pneumonia. Also if suspected TB or PCP, but inadequate or
sputum cx. Some pathogens need specific cx (eg,
Legionella
on BCYE); collaborate with lab.