Small Cell Lung Cancer (SCLC)

Background: 

• SCLC is a poorly differentiated neuroendocrine carcinoma.

  • Small blue cells, scant cytoplasm, high N:C ratio, granular chromatin

• Types:

  • Limited-Stage SCLC (LS-SCLC):

    • Stages I–III confined to the ipsilateral hemithorax that can be safely encompassed within a radiation field

      • Some stage III tumors are considered extensive-stage when the disease burden is too extensive to be safely encompassed in a tolerable radiation field.

  • Extensive-Stage SCLC (ES-SCLC):

    • Stage IV disease/Metastatic, beyond the ipsilateral hemithorax, including malignant pleural or pericardial effusion

    • Stage I–III disease that cannot be safely encompassed within a definitive thoracic radiation field.

• Median overall survival:

  • LS-SCLC: ~15–30 months with treatment

  • ES-SCLC: ~10–13 months with treatment

• Five-year survival:

  • LS-SCLC: ~20–30%

  • ES-SCLC: <5%

• May present with SVC Syndrome

  • IR consult:

    • Obtain tissue diagnosis before treatment whenever feasible and safe

    • SVC stenting in patients with severe/life-threatening symptoms for rapid relief

  • Rad Onc consult:

    • Urgent radiotherapy when indicated

      
      

Work up:

• Biopsy or cytology

  • EBUS-guided biopsy of the primary or thoracic nodes, or biopsy of a metastatic lesion

• Labs:

  • CBC, electrolytes, LFTs, BUN/creatinine

    • Unexplained hyponatremia → require SIADH work up

    • Hypokalemia, metabolic alkalosis, new or refractory hyperglycemia → ectopic ACTH/ Cushing syndrome

      • Almost all of these patients have weight loss (unlike classic Cushing) so absence of the cushingoid habitus does not exclude it.

  • LDH

    • Elevated LDH may reflect greater disease burden and is associated with worse prognosis.

• Imaging:

  • CAP CT scan

  • Brain MRI with contrast

    • ~15% have brain metastases at diagnosis

  • Consider FDG-PET/CT when limited-stage disease is suspected to identify occult distant metastases and assist with radiation planning.

    • If PET CT scan is unavailable, bone scan may be used.

    • PET/CT does not replace brain MRI.

• Smoking cessation counseling

• Consider biomarker testing:

  • Extensive-stage in never- smoker or light-smokers

  • Remote smoking history

  • Diagnostic or therapeutic dilemma

  • Relapse

• Palliative care integration

  
  

Treatment:

LS-SCLC

• Curative-intent therapy

• Stage I-IIA (T1-2 , N0):

  • lobectomy mediastinal lymph node dissection/sampling + adjuvant chemotherapy (Carboplatin/cisplatin + Etoposide)

    • Invasive mediastinal staging is mandatory before resection. Patients with pathologic nodal involvement should be managed as stage IIB–IIIC disease.

• Stage IIB-III:

  • Concurrent chemo-RT → consolidation Durvalumab (ADRIATIC)

    • OS was 55.9 months (durvalumab) vs 33.4 months (placebo)

    • PFS was 16.6 months (durvalumab) vs 9.2 months (placebo)

  • Thoracic RT should begin with cycle 1 or 2 of chemotherapy.

    • Do not delay RT until completion of induction chemotherapy.

  • Myeloid growth factors are not recommended during concurrent chemo-RT.

  • Consider prophylactic cranial irradiation (PCI) in patients with a good response to definitive therapy, which reduces the incidence of brain metastases and has demonstrated an overall survival benefit.

    • PCI should be completed before initiating consolidation durvalumab.

  • Brain surveillance imaging is recommended for all patients regardless of PCI status.

ES-SCLC

• Systemic therapy is the backbone of treatment.

• No role for surgery

• Brain RT is used selectively rather than routinely.

  • If asymptomatic: give systemic therapy first and defer brain RT

  • If symptomatic: give brain RT + steroids before systemic therapy

• Consider consolidative thoracic RT after systemic therapy in selected responders with residual thoracic disease.

• Chemo-IO options:

  • (Carboplatin/cisplatin + Etoposide) + Durvalumab x4 cycles → Maintenance: Durvalumab (CASPIAN)

  • (Carboplatin/cisplatin + Etoposide) + Atezolizumab x4 cycles → Maintenance: Atezolizumab (IMPOWER-133)

  • (Carboplatin/cisplatin + Etoposide) + Atezolizumab x4 cycles → Maintenance: Atezolizumab+lurbinectedin (IMforte)

Relapsed cases

• The important questions is: 'When did the relapse occur?'

  • Relapse > 6 months after platinum exposure (Platinum-sensitive relapse):

    • Repeat original regimen (Carboplatin/cisplatin + Etoposide)

  • Relapse ≤ 6 months after platinum exposure (Platinum-resistant relapse):

    • Lurbinectedin

    • Topotecan

    • Tarlatamab: bispecific Ab (DeLLphi-301)

    • Clinical Trial