#358 Oncologic Emergencies with Dr. Aditi Singh

October 3, 2022 | By Matthew Watto, MD

Video

From Cord Compression to Tumor Lysis Syndrome

Do you freak out over oncologic emergencies like cord compression or tumor lysis syndrome? Join Dr. Aditi Singh (University of Pennsylvania, Abramson Cancer Center, @AditiSinghMD) for this comprehensive conversation on six commonly encountered oncologic emergencies we see in the hospital!

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Credits

• Producer, Writer, Hosts: Meredith Trubitt, MD MPH; Monee Amin, MD
• Infographic and Cover Art: Caroline Coleman
• Hosts: Matthew Watto MD, FACP; Paul Williams MD, FACP   
• Associate Editor: Leah Witt, MD
• Showrunner: Matthew Watto MD, FACP
• Technical Production: PodPaste
• Guest: Aditi Singh, MD

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CME Partner: VCU Health CE

Show Segments

• Intro, disclaimer, guest bio
• Guest one-liner, Picks of the Week*
• Cord Compression
• SVC Syndrome
• Malignant Obstruction
• Tumor Lysis Syndrome
• Blast Crisis
• Outro

Oncologic Emergencies Pearls

1. Do not wait for permission to order steroids for cord compression.
2. The most common presenting symptom of cord compression is back pain, and it may not present with the classic triad of cauda equina syndrome.
3. Malignant SVC syndrome can be associated with thrombus, which requires treatment with anticoagulation.
4. Malignant bowel obstruction or pseudo-obstruction may be due to other risk factors besides current cancer diagnosis such as pain medications (e.g. opioids), prior surgeries, prior pelvic radiation, or current cancer-specific treatment.
5. Elevated calcium levels may be an early sign of cancer recurrence for some cancer types, most commonly breast, lung, and multiple myeloma..
6. Cairo-Bishop criteria can be used for diagnosis of lab-based or clinical tumor lysis syndrome.
7. For patients with hypocalcemia in tumor lysis syndrome, treat with a phosphorus binder, because the mechanism of hypocalcemia is elevated serum phosphorus which binds calcium. Calcium repletion may result in precipitation of calcium phosphate in renal tubules resulting in acute kidney injury.
8. For patients who present with hyperleukocytosis, be cognizant of leukostasis as a potentially fatal complication.

Oncologic Emergencies Notes

Cord Compression

Diagnosis 

Dr. Singh reminds us that the most common presenting symptom of cord compression is back pain. On initial evaluation, pain is present 83-95% of the time, followed by weakness (35-75%) and less commonly sensory changes (Lawton, 2019). Dr. Singh reminds us to avoid the common trap of only looking for cauda equina syndrome. If the compression is above the level of the cauda equina, the patient will not present with the classic triad of saddle anesthesia, bowel and/or bladder dysfunction, and lower extremity weakness. In fact, the thoracic spine is most commonly affected, followed by lumbosacral and then cervical (Lawton, 2019).

Diagnosis requires imaging, and MRI is the standard of care as it has 93% sensitivity and 97% specificity in detection of malignant spinal cord compression (Lawton, 2019). 

Cancers which are predisposed to cord compression include prostate, lung, breast, and multiple myeloma (Higdon, 2018). Anyone with cancer who presents vague back pain, especially with paresthesias should be ruled out for cord compression (expert opinion). 

Treatment

As soon as you get the call for admission, Dr. Singh says not to hesitate to order an initial steroid dose (typically dexamethasone 10 mg, followed by 4 mg every 6 hours). Ultimately, the specialists should provide the duration and taper for steroids. Length of steroid treatment is dependent on length of radiation therapy, type of cancer, and surgical plan, so should be determined by the multidisciplinary team (expert opinion).

The multidisciplinary team will consist of neurosurgery (or local spine surgery team) and radiation oncology. The patient’s surgical candidacy is up to the surgeon, but Dr. Singh provided the mnemonic NOMS (Neurologic, Oncologic, Mechanical, Systemic) that the surgeon may use to determine candidacy (Laufer, 2013).

• Neurologic:  What are the neurologic deficits present? 
• Oncologic: Where is the patient in their cancer journey? Is the cancer type chemo or radiosensitive as an additional therapeutic option?
• Mechanical: How stable is the spine, and can surgery safely be done?
• Systemic: What is the patient’s overall health status and can they tolerate surgery?

Premorbid functional status is an important factor for overall functional prognosis, and explains the reason for quick action (Lawton, 2019).

SVC Syndrome

Diagnosis

SVC syndrome is caused by compression of the superior vena cava and the hallmark finding is facial edema (Higdon, 2018). SVC syndrome is a clinical diagnosis and other signs/symptoms may be present as well including distended neck veins, cough, dyspnea, orthopnea, upper extremity swelling, distended chest vein collaterals, and/or conjunctival suffusion. Less commonly SVC syndrome can present with stridor, hoarseness, dysphagia, pleural effusion, head plethora, headache, nausea, lightheadedness, syncope, change in vision, altered mental status, upper body edema, cyanosis, papilledema, stupor, and/or coma (Seligson, 2022). 

Dr. Singh points out that the presence of particular associated symptoms distinguish SVC syndrome as either an oncologic urgency vs emergency. This is important as it is necessary to determine how much time the team has to tailor the treatment to the patient. She explains if the patient has signs or symptoms of airway obstruction, altered mental status due to cerebral edema, laryngeal edema, or signs of arrhythmia due to compression of the heart, these are all reasons the SVC syndrome would be classified as an emergency. 

While diagnosis of SVC syndrome is clinical, it is important to confirm with a CT scan of the neck with IV contrast. If the patient cannot tolerate contrast, then order MR venography instead. The imaging can help discern location, severity, and etiology to help guide treatment options and timing (Seligson, 2022).

The cancers most predisposed to SVC syndrome include lung, non-Hodgkin lymphoma, thymic, germ cell, breast, and mesothelioma. 

Treatment

The first step to treatment is to ensure stability of the patient (e.g. evaluate airway and breathing).. The next steps are involving the multidisciplinary team which will include vascular surgery for possible endovascular stenting to alleviate the obstruction (Higdon, 2018) as well as radiation oncology. 

Additionally, Dr. Singh recommends additional oncologic evaluation to consider chemotherapy and/or radiation depending on tumor sensitivity. This could be complicated if SVC syndrome is the presenting symptom of a new cancer diagnosis, as it is  necessary to get a histologic diagnosis first to initiate appropriate cancer-directed treatment.

Lastly, if SVC syndrome is found with an associated thrombus, the team will need to consider anticoagulation. Depending on other procedures needed (i.e. endovascular intervention), catheter-directed thrombolysis may be a possible treatment modality (Seligson, 2022). 

Malignant Obstruction

Diagnosis

The most common associated symptoms include: nausea, vomiting, colicky abdominal pain, and the absence of flatus or stool in the last 72 hours (Ferguson, 2015). Dr. Singh urges us to remember that even if someone has an underlying cancer, their obstruction may not be due to the malignancy but other risk factors such as prior surgery, prior pelvic radiation, opioids or cancer-specific treatment causing pseudo-obstruction.

Cancers most commonly associated with malignant obstruction include colorectal, ovarian, peritoneal metastasis, and melanoma. 

If there is a high suspicion for obstruction or even with confirmed obstruction on abdominal x-ray, it is important to get a CT abdomen/pelvis with contrast to provide more information about the transition point, partial vs complete obstruction, and high or low grade obstruction, as these answers all impact surgical decision-making (expert opinion).

As with all oncologic emergencies, the primary team needs to involve the multidisciplinary team managing this patient, including medical oncology, general surgery, and palliative care. 

Treatment

Initial therapies include conservative management of IV fluids, NPO, NG tube for decompression, electrolyte repletion as well as symptom control for both pain and nausea. Considerations for symptomatic control include somatostatin analogues which decrease secretions and motility, scopolamine, and steroids (Ferguson, 2015).

Nutrition is often a central concern, particularly for the patient and their family. Therefore, total parenteral nutrition (TPN) may come up in family discussions. Dr. Singh notes that while this is an available treatment modality, it is very dependent on where the patient is in their cancer journey. If the underlying malignancy cannot be treated, then starting TPN may prolong longevity without improving quality, thereby requiring a multidisciplinary discussion with the patient’s primary oncologist and likely palliative care provider.

Lastly, Dr. Singh highlights that malignant obstruction often results in recurrent admissions and a venting G-tube may be considered as a palliative measure.

Hypercalcemia of Malignancy

For a full review of hypercalcemia, please refer to episode 281. 

Dr. Singh had a couple of pearls she wanted to highlight regarding hypercalcemia in the setting of malignancy. First, the most common associated cancers with this condition are squamous cell cancer from the lung or head and neck, which is mediated by parathyroid related protein (PTHrP). It is also associated with multiple myeloma due to lytic lesions and lymphoma due to activation of vitamin D.

The ultimate treatment for hypercalcemia of malignancy is treating the underlying cancer, but the initial mainstay of therapy is fluids. A newly uptrending calcium may be the first sign that there is recurrence of malignancy.

Tumor Lysis Syndrome

Pathophysiology

Tumor lysis syndrome can occur spontaneously or after initiating therapy. When it occurs spontaneously, the tumor is outgrowing its blood supply resulting in lysis of tumor cells. When it occurs after initiating therapy, the cell death is intentional, but still results in lysis of tumor cells (Howard, 2018). As Dr. Singh says, whatever is inside the cell comes out when the cell dies which includes potassium, phosphorus, and uric acid. The increasing serum phosphorus then binds to calcium ions which drives calcium levels down, which can lead to dangerous hypocalcemia. 

Diagnostic Criteria

Cairo-Bishop Criteria defines tumor lysis syndrome (Howard, 2018). 

Laboratory tumor lysis syndrome: requires two of the below serologic criteria within the same 24 hour period either 3 days before starting therapy or up to 7 days afterward: 

• Potassium > 6 mmol/L
• Phosphorus > 4.5 mg/dL
• Uric acid > 8 mg/dL
• Corrected Calcium < 7 mg/dL

Clinical tumor lysis syndrome: requires meeting laboratory tumor lysis syndrome criteria (listed above) PLUS one of the following: 

• Acute kidney injury 
• Seizures
• Cardiac dysrhythmia
• Death 

Dr. Singh reminds us that while we often obtain LDH levels, this is not part of the criteria for TLS diagnosis. LDH is a marker of high cell turnover and suggests risk of TLS however it should not be used to monitor for TLS by itself.

Common cancers at high risk for TLS are high-turnover hematologic malignancies such as: Burkitt’s lymphoma, diffuse large B cell lymphoma, ALL, CLL (especially with an elevated WBC#). TLS can be seen rarely with some solid tumor malignancies such as small cell lung cancer or colorectal cancer. 

Treatment

Management is aimed at preserving renal function. Dr. Singh recommends that treatment to avoid renal failure should include high rate maintenance intravenous fluids such as 150-250 cc/hr. 

Additionally, treatment is aimed at carefully managing electrolytes, Dr. Singh warns against the common pitfall of repleting hypocalcemia, as this may result in more precipitation of bound calcium and phosphorus, which can worsen acute kidney injury. She reminds us that phosphorus binders should be the mainstay of treatment as they treat both the phosphorus and calcium abnormalities.

Both allopurinol and rasburicase are used to decrease byproducts which can precipitate and lead to nephropathy. Allopurinol prevents the formation of uric acid, but it does not do anything to uric acid that has already been formed, therefore it is used in TLS prevention but not acute treatment. Despite using allopurinol, urate nephropathy can occur. Additionally, allopurinol is a xanthine oxidase inhibitor, therefore xanthine accumulation can occur and lead to xanthine nephropathy (Howard, 2018). Allopurinol must be renally dosed, but if the patient can tolerate it, the goal is to use a high dose (e.g. 300 mg).

Rasburicase prevents xanthine accumulation and directly breaks down uric acid so is used for tumor lysis treatment for renal protection (Howard, 2018). Dr. Singh reminds us that we should check G6PD levels because patients who are deficient and treated with rasburicase could develop a methemoglobinemia or in severe cases, hemolytic anemia. 

Blast Crisis and Leukostasis 

Definitions

Hyperleukocytosis is a WBC count over 100,000/microL, without clinical signs and symptoms.  

Blast crisis is the presence of greater than 20% of peripheral or bone marrow blast cells.

Leukostasis is hyperleukocytosis with neurologic or pulmonary manifestations.  

Diagnosis

Clinical manifestations of blast crisis include anemia, thrombocytopenia, bleeding, bone pain, and immunosuppression, all associated with the invasion of bone marrow. Hyperleukocytosis, if untreated, can develop into three major complications: leukostasis, DIC, and/or TLS (Emerson, 2018). 

The most common cancers at risk for leukostasis are AML or CML (and less commonly ALL and CLL) (Emerson, 2018). In considering initial work-up, Dr. Singh recommends a peripheral smear to better assess the type of blasts and to rule out APML. Additionally, she recommends a set of coags to better assess DIC risk, and electrolytes as above for TLS evaluation. 

Leukostasis is a rare complication, but can be fatal, so Dr. Singh urges hospitalists to have a high index of suspicion for patients presenting with hyperleukocytosis. 

CNS signs and symptoms include: headache, confusion, blurred vision, altered mental status, focal numbness or weakness. Pulmonary signs and symptoms include: dyspnea, tachypnea, and hypoxemia. Other manifestations include: priapism, limb ischemia, renal insufficiency, and renal vein thrombosis (Emerson, 2018).

Treatment

Treatment decisions for blast crisis and leukostasis should be guided by the patient’s primary medical oncologist.  The mainstay of treatment is to treat the underlying malignancy. Hydroxyurea may be started early, especially if in an asymptomatic phase (Emerson, 2018). Starting IVFs to decrease the viscosity can be temporizing (Emerson, 2018). Dr. Singh recommends avoiding blood transfusion as this may increase the viscosity, thereby precipitating leukostasis (expert opinion). 

Leukapheresis has not shown significant improvement in mortality or morbidity, but if someone is demonstrating symptoms consistent with leukostasis and not responding to hydroxyurea nor underlying cancer treatment fast enough, leukapheresis may be the only treatment option available (expert opinion). 

Links

1. Letter to a Young Female Physician by Suzanne Koven
2. Somebody Feed Phil
3. I’ll Have What Phil’s Having
4. Naked Lunch
5. Monee’s “The Vault” Playlist on Spotify

Goal

Listeners will develop a framework for diagnosis and early management of common oncologic emergencies encountered in the hospital. 

Learning objectives

After listening to this episode listeners will…  

1. List potential inpatient oncologic emergencies.
2. Identify early signs of cord compression and initial management options.
3. Compare and contrast imaging modalities available to identify SVC syndrome.
4. Explain the pathophysiology of tumor lysis syndrome.
5. Discern the difference between leukostasis and blast crisis.

Disclosures

Dr. Singh reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures. 

Citation

Trubitt MT, Amin MA, Singh, A. “#358 Oncologic Emergencies”. The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list October 3rd, 2022.