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Small Cell Lung Cancer (SCLC)

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Small Cell Lung Cancer (SCLC)

Small cell lung cancer (SCLC) is a high-grade neuroendocrine lung carcinoma
characterized by rapid growth, early metastasis, and a strong association with cigarette
smoking. It is typically located centrally within the lung

Also called

Oat cell carcinoma — older name

ICD-10

C34

Specialty

Pulmonology

Onset

Chronic

Reviewed

July 2026

On This Page

Overview

SCLC is an aggressive neuroendocrine tumor arising from Kulchitsky cells. Although it
often responds well initially to chemotherapy, recurrence is common, and many patients
present with advanced disease.

Etiology & Risk Factors

Etiology

Main cause:

  • Cigarette smoking — strongly associated with SCLC

Other causes include long-term exposure to:

  • Secondhand smoke
  • Occupational carcinogens
  • Air pollution

Risk Factors

  • Heavy cigarette smoking
  • Long smoking duration
  • Older age
  • Secondhand smoke exposure
  • Occupational exposure to:
    • Asbestos
    • Radon
    • Arsenic
    • Chromium
    • Nickel
  • Previous radiation exposure

Pathophysiology

• Originates from neuroendocrine (Kulchitsky) cells
• Rapid growth
• High mitotic activity
• Early metastatic spread
• Frequently associated with paraneoplastic syndrome

Clinical Presentation

  • Patients may present with:
    • Pulmonary symptoms
    • Extrapulmonary symptoms
    • Paraneoplastic syndromes
    • Features of metastatic disease
    SCLC commonly presents at an advanced stage due to its rapid progression.

History Taking

-Assess for:
• Smoking history
• Respiratory symptoms
• Constitutional symptoms
• Symptoms suggestive of paraneoplastic syndromes
• Symptoms suggestive of metastatic disease

Physical Examination

-Assess for:
• Respiratory findings
• Evidence of metastatic disease
• Signs of paraneoplastic syndromes
• General performance status

Investigations of Small Cell Lung Cancer (SCLC)

-Imaging :
• CT chest (initial evaluation)
• Further staging imaging as indicated


-Tissue diagnosis :
• Bronchoscopic biopsy
• CT-guided biopsy
Histopathology
Characteristic findings:
• Small, dark blue neuroendocrine (Kulchitsky) cells
• Hyperchromatic nuclei with “salt-and-pepper” appearance
• Scant cytoplasm
• High mitotic rate (>10 mitoses/2 mm²)


-Immunohistochemical markers :
• Chromogranin A
• Synaptophysin
• Neuron-specific enolase (NSE)
• CD56

Diagnosis of Small Cell Lung Cancer (SCLC)

-Diagnosis is based on:
• Clinical evaluation
• Chest CT
• Histopathological confirmation by biopsy
• Immunohistochemical staining

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Management Small Cell Lung Cancer (SCLC)

-Management depends on disease stage and should involve a multidisciplinary tumor board whenever available.


Limited-stage disease
Stage I–II (N0)
• Consider surgical resection


-All patients
• Systemic therapy
• Concurrent radiotherapy
• Consider prophylactic cranial irradiation (PCI)


-Extensive-stage disease
• Palliative chemotherapy
• Chemotherapy with or without immunotherapy
• Consider prophylactic cranial irradiation (PCI) or MRI surveillance


-General points
• Early palliative care improves quality of life and may prolong survival.
• Most patien

Complications

• Early distant metastases
• Paraneoplastic syndromes
• Disease recurrence (commonly within 6 months after initial chemotherapy response)

Prognosis of Small Cell Lung Cancer (SCLC)

• Very aggressive malignancy.
• Good initial response to chemotherapy is common.
• Most patients relapse within approximately 6 months.
• Overall prognosis is poor because most patients present with advanced disease.

Key Points / Clinical Pearls of Small Cell Lung Cancer (SCLC)

• High-grade neuroendocrine lung carcinoma.
• Strongly associated with smoking.
• Usually centrally located.
• Rapid growth with early metastasis.
• Originates from Kulchitsky cells.
• Positive neuroendocrine markers:
• Chromogranin A
• Synaptophysin
• Neuron-specific enolase
• CD56
• Diagnosis requires biopsy