Four oncologic emergencies to watch out for in primary care

By Naveed Saleh, MD, MS | Medically reviewed by Jeffrey A. Bubis, DO, FACOI, FACP
Published February 7, 2024

Key Takeaways

  • Because cancer treatment is often done on an outpatient basis, community healthcare providers can encounter oncologic emergencies.

  • Oncologic emergencies are usually hematologic, metabolic, structural, or treatment-related.

  • Stabilization of oncologic emergencies can involve intravenous fluids.

An estimated 16 million people in the US are living with cancer, according to research published in CA: A Cancer Journal for Clinicians.[] And because oncology care has transitioned to outpatient settings, urgent complications are being treated in acute care settings, such as the emergency department. Patients with oncologic emergencies are also often encountered in primary care settings.

These emergencies represent a variety of pathogenesis, including malignancy, disease progression, cancer recurrence, and adverse effects of treatment. Some can be deadly and necessitate prompt stabilization and triage, according to an American Family Physician article.[]

Most oncologic emergencies fall into the categories of metabolic, hematologic, structural, or treatment-related.

Tumor lysis syndrome

This condition is caused by rapid, acute cell lysis that occurs after cancer treatment. Although it is most often seen with chemotherapy, it can also occur following radiation and biologic therapies, according to the American Family Physician research.

Due to an increased number of ambulatory infusion centers, PCPs can encounter tumor lysis syndrome when assessing standard post-cancer treatment lab results or in patients who have complications.

With this syndrome, the release of intracellular products, such as phosphates, uric acid, calcium, and potassium, disrupts the body homeostasis. This complication most often occurs with solid tumors—in particular, hematologic malignancies like acute leukemia or high-grade lymphoma.

Patients with tumor lysis syndrome can exhibit acute renal failure, azotemia, hyperphosphatemia, hyperuricemia, hyperkalemia, and hypocalcemia.

Tumor lysis syndrome typically occurs within 7 days of cancer treatment. Patients with renal disease are at higher risk of renal failure as a result of tumor lysis syndrome.

To stabilize patients with tumor lysis syndrome, volume expansion is required, with urine output maintained. Uric acid levels should be lowered and the intake of potassium/phosphorus limited during high-risk periods (for example, 3–7 days before cancer treatment).

The patient should be quickly transferred to the care of an inpatient oncology team. With severe acute renal insufficiency, nephrologists should be consulted, and early hemodialysis may be required.

Febrile neutropenia

One of the most frequent complications of cancer treatment, febrile neutropenia can arise from the use of antineoplastics of any type but is most frequently associated with cytotoxic therapies such as anthracyclines, topoisomerase inhibitors, platinums, gemcitabines, alkylating agents, and more, according to American Family Physician.

Symptoms of febrile neutropenia include high temperatures and low absolute neutrophil counts.

Patients with high-risk febrile neutropenia require blood cultures and inpatient treatment with empiric antibiotics until their ANC levels are at least 500 cells per mm3 for 72 hours. Low-risk patients can be treated as outpatients.

Research data suggest that the use of antibiotics within 30 minutes of the presentation of febrile neutropenia improves survival. The patient should be immediately referred to oncologists and infectious disease specialists.


As many as 15% of cancer patients experience paraneoplastic syndromes. Most of these are endocrine-mediated and reflect the secretion of bioactive substances, according to the CA: A Cancer Journal for Clinicians article.

Syndrome of inappropriate antidiuretic hormone (SIADH) commonly presents with small cell lung cancer and affects 10%–15% of patients with this cancer. SIADH can also accompany other aerodigestive tract tumors or result from extreme cancer pain. It is also seen in patients with central nervous system disease.

Physicians may suspect SIADH in individuals with cancer who present with hyponatremia. It’s important to recognize this condition quickly to improve outcomes, as severe hyponatremia is dangerous. Small cell lung cancer, which can arise in the lung or be extrapulmonary, is often the ectopic source of antidiuretic hormone production.

Patients with SIADH can exhibit gastrointestinal and neurological symptoms with few overt physical findings. Papilledema and pathologic reflexes, such as the Babinski sign, may be present. Metabolic panels identify hyponatremia, decreased serum osmolarity, and concentrated urine.

An emerging agent to treat SIADH is tolvaptan (Samsca), a selective vasopressin V2 receptor antagonist that raises free water excretion. There are, however, concerns about liver injury related to tolvaptan, according to the research.

On stabilization, the care of cancer patients with SIADH should be referred to oncologists and nephrologists.


Between 10% and 30% of patients with cancer exhibit hypercalcemia; it is most often seen with breast, renal, lung, and squamous cell cancers and multiple myeloma, according to research published in Cancer Medicine.[]

Hypercalcemia presents with vague symptoms, often reflective of volume depletion secondary to osmotic diuresis associated with hypercalcemia, according to research published by Western Journal of Emergency Medicine.[]

These symptoms include anorexia, nausea/vomiting, and constipation. Lethargy, confusion, and coma may also result. Calcium and ionized calcium levels should be tested. 

The treatment for hypercalcemia begins with volume expansion. Other possible treatments include bisphosphonates, loop diuretics, and glucocorticoids.

Patients with few symptoms can be managed as outpatients if determined so by their oncologist.

Patients with moderate or severe hypercalcemia may require admission to the ICU. 

Get familiar

Although oncologic emergencies will frequently be referred to oncologists and other specialists, PCPs and other general physicians may want to consider familiarizing themselves with these conditions.

Such knowledge will enable them to better care for patients who arrive presenting with these symptoms by stabilizing the patient before they are referred to their oncologist.

What this means for you

Patients with cancer are routinely treated on an outpatient basis. Emergency presentations in patients with cancer can occur in a variety of healthcare settings including primary care clinics and emergency departments. Various types of physicians, including PCPs, should be equipped to stabilize oncologic emergencies before referring care to the patient’s oncologist.

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