What is the recommended treatment for early-stage lung cancer using Stereotactic Ablative Body Radiotherapy (SABR)?

From the Guidelines

Stereotactic Ablative Body Radiotherapy (SABR) is the recommended treatment for early-stage lung cancer in patients who are medically inoperable or who decline surgery, with a biologically equivalent tumor dose of ≥100 Gy, prescribed to the encompassing isodose 1.

Key Considerations

• The standard SABR regimen typically delivers high doses of radiation in 1-5 fractions, with common dose schedules including 54 Gy in 3 fractions, 48 Gy in 4 fractions, or 50 Gy in 5 fractions.
• Treatment is usually completed within 1-2 weeks, which is significantly shorter than conventional radiotherapy that may take 6-7 weeks.
• Prior to treatment, patients require a planning CT scan with 4D imaging to account for respiratory motion, and fiducial markers may be placed to improve targeting accuracy.
• During treatment, patients are immobilized using custom body molds, and image guidance is used to ensure precise delivery.

Efficacy and Safety

• SABR is effective because it delivers ablative doses of radiation that cause direct tumor cell death while minimizing exposure to surrounding healthy tissue.
• This approach achieves local control rates of 85-95% for early-stage lung cancer, comparable to surgical outcomes.
• Side effects are generally mild and may include fatigue, mild radiation pneumonitis, and chest wall pain, particularly for tumors close to the ribs.

Follow-up and Monitoring

• Follow-up typically includes CT scans every 3-6 months for the first 2 years, then annually thereafter to monitor for recurrence.
• The risk of high-grade toxic effect was <9% when the biologically equivalent normal tissue dose was ≤210 Gy 1.

Special Considerations

• For tumours with a size >5 cm and/or central location, radical radiotherapy using more conventional daily or accelerated schedules is recommended 1.
• SABR for early-stage peripheral lung tumours is associated with low toxicity in patients with COPD and the elderly 1.

From the Research

Treatment Overview

The recommended treatment for early-stage lung cancer using Stereotactic Ablative Body Radiotherapy (SABR) is a method of delivering high 'ablative' doses of radiotherapy to tumors in the lung 2. This treatment has been shown to offer higher rates of local control, lower levels of acute toxicity, and a better quality of life after treatment compared to conventionally fractionated radiotherapy.

Key Findings

• High rates of local control and low levels of acute and late toxicity are consistently reported in the published literature for peripheral primary lung cancers less than 5 cm in diameter treated with SABR 2.
• SABR can be used for tumors metastatic to the lung with high rates of local control and is a reasonable alternative to surgery in selected patients 2.
• For central lung tumors, very high SABR doses can be associated with significant toxicity, but dose-adapted fractionation schedules seem to have much lower rates of toxicity 2.
• SABR achieves promising long-term tumor control and survival and may be a potential curative treatment for early stage multiple primary lung cancer (MPLC) 3.

Patient Outcomes

• The median overall survival for patients with early stage peripheral lung cancer treated with SABR was 27.3 months, with 1,2, and 3-year overall survival rates of 78.0,54.9, and 38.6%, respectively 4.
• The 1,2, and 3-year rates of local control for patients with early stage peripheral lung cancer treated with SABR were 98.2,95.7, and 95.7%, respectively 4.
• Patients with MPLC who received SABR had a median overall survival of 46 months, with 2-year and 4-year in-field local control rates of 97.4 and 95.7%, respectively 3.

Treatment Considerations

• SABR should be considered when patients with lung cancer present with a synchronous second lesion and no nodal involvement 5.
• Patients with Medical Research Council (MRC) breathlessness scores of 3-5 had worse overall survival compared to patients with scores of 1-2, and the presence of histological diagnosis conferred improved overall survival 4.
• The incidence of grade ≥ 3 radiation pneumonitis was 3% for patients who underwent surgery or received SABR for an index tumor, but increased to 17% for those who received conventional radiotherapy for an index tumor 3.