What is SABR (Stereotactic Ablative Radiotherapy) LUNG?

Stereotactic Ablative Radiotherapy (SABR) for Lung Cancer

SABR LUNG is a highly precise radiation therapy technique that delivers very high doses of radiation to lung tumors with extreme accuracy, used primarily for early-stage non-small cell lung cancer (NSCLC) in medically inoperable patients or those who refuse surgery. 1

Definition and Technical Aspects

SABR (also known as Stereotactic Body Radiation Therapy or SBRT) is an advanced external beam radiation technique characterized by:

• Delivery of very high radiation doses with exceptional precision
• Treatment completed in a limited number of fractions (typically 3-5)
• Biological equivalent dose (BED10) of at least 100 Gy
• Highly conformal dose distribution to minimize damage to surrounding healthy tissue

Clinical Indications

Primary Indication

• Medically inoperable patients with stage T1-2N0M0 NSCLC 1
• Operable patients who refuse surgical intervention 1

Contraindications

• Patients with very limited life expectancy due to severe comorbidities 1
• Caution required for:
  • Central tumors
  • Large volume tumors
  • Patients with severe pulmonary comorbidity 1

Efficacy and Outcomes

SABR has demonstrated superior outcomes compared to standard external-beam radiation therapy (EBRT) for early-stage NSCLC:

• Higher local control rates
• Better cancer-specific survival
• Acceptable toxicity profile 1

Standard EBRT techniques typically result in:

• Local 3-year recurrence rates of 29-57%
• Overall survival rates of only 20-50% 1

Dosing Considerations

• Optimal biological equivalent dose (BED10) should be at least 100 Gy 1
• Evidence suggests doses higher than 150 Gy could be detrimental 1
• For high-risk cases (central tumors, large tumors, severe pulmonary comorbidity), a risk-adapted schedule should be used:
  • Dose reduction
  • Increase in number of fractions 1

SABR vs. Surgery

Despite promising results with SABR, surgery remains the standard of care for operable patients with early-stage NSCLC:

• Lobectomy (or pneumonectomy when appropriate) is still considered the standard treatment for operable patients 1
• Surgery provides additional benefits:
  • En bloc resection of the primary tumor
  • Removal of draining lymph nodes
  • Definitive assessment of tumor histology
  • Mediastinal staging 1

Special Considerations

Large Tumors (≥5 cm)

While traditionally excluded from SABR trials, recent research shows SABR may be effective for larger tumors with:

• Acceptable local control rates
• Manageable toxicity profile 2

Patient Selection

Treatment decisions should be discussed in multidisciplinary tumor boards, considering:

• Severity of comorbidities
• Advantages and disadvantages of available treatments
• Local expertise 1

Potential Complications

Despite a generally favorable toxicity profile, SABR can produce serious complications, particularly in:

• Central tumors
• Large volume tumors
• Patients with severe pulmonary comorbidity 1

Summary of Recommendations

1. For medically operable patients with stage T1-2N0M0 NSCLC, surgery remains the standard treatment 1
2. For medically inoperable patients with stage T1-2N0M0 NSCLC or medically operable patients who refuse surgery, SABR should be preferred over standard EBRT 1
3. The biological equivalent dose (BED10) used for SABR treatment should be at least 100 Gy 1
4. For patients with central tumors, large-volume tumors, or severe pulmonary comorbidity, a risk-adapted schedule should be used 1
5. SABR should not be considered for patients whose life expectancy is very limited due to comorbidities 1