The American Society for Radiation Oncology (ASTRO) has released new clinical guidelines that recommend the use of stereotactic body radiation therapy (SBRT) in early-stage lung cancer.
 
Currently, SBRT is the standard of care for patients with peripherally located tumors that are inoperable. The new guidelines address the use of SBRT for medically inoperable patients with high-risk clinical scenarios that require curative focused therapy.
 
Additionally, the guidelines offer detailed principles of SBRT directed toward centrally located lung tumors. The appropriateness of SBRT in operable patients was also addressed.
 
The guidelines––which drew on data from retrospective and prospective studies and randomized clinical trials­­––provides evidence-based recommendations on the appropriate use of SBRT for early-stage non-small cell lung cancer (NSCLC).
 
The appropriateness of SBRT as an alternative to surgery for different subsets of medically operable patients with early-stage NSCLC differs among patients who are at high risk or standard risk of surgery-related mortality.
 
For standard risk, SBRT is not recommended as an alternative to surgery outside of the clinical trial setting for patients with stage 1 NSCLC who have an anticipated risk of operative mortality of less than 1.5%. A lobectomy with systematic mediastinal lymph node evaluation remains the recommended treatment for these patients.
 
For high risk patients, discussions about SPBRT as an alternative to surgery is recommended for patients with stage 1 NSCLC who are at a greater risk of surgical morbidity or mortality, or who cannot tolerate a lobectomy but are candidates for sublobar resection. However, the guidelines note that health care providers should let patents know that although short-term treatment-related risks are lower with SBRT, long-term outcomes more than than 3 years are not well-established in studies.
 
To reduce potential specialty bias, a thoracic surgeon should evaluate any potentially medically operable patients with early-stage NSCLC who are considering SPRT––preferable in a multidisciplinary setting.
 
Recommendations for inoperable patients are varied based on tumor location, type, size, and treatment history.
 
SBRT is appropriate for centrally located tumors, but the associated toxicity risk depends on the total dose and fractionation schedule. Therefore, SBRT should be delivered in 4 or 5 fractions as a function of total dose, the guidelines states.
 
Additionally, the use of stereotactic treatment for centrally located lung tumors close to or involving specific critical structures should be considered because of the risk of rare but potentially severe adverse events after receiving high-dose treatments.
 
For tumors that are larger than 5 cm that cannot be surgically removed, SBRT is conditionally recommended, but patients should be counseled about the subsequent risk of locoregional and distant failure.
 
Although a biopsy should be used whenever possible to confirm tumor malignancy, SBRT can be considered for patients who are unable or unwilling to undergo a biopsy. Such cases should be discussed prior to treatment at a multidisciplinary tumor board.
 
SBRT can be considered as a curative-intent treatment option for patients with a history of previously resected lung cancers––either singly or multiply––and/or who received a pneumonectomy for prior lung cancer and now have a new primary tumor in their remaining lung(s).
 
The following guidelines outline how SBRT techniques should be tailored to high-risk scenarios where the tumor abuts critical structures among medically inoperable patients:
  • Tumors that touch the trachea or proximal bronchial tree––or tumors near the heart and pericardium––SBRT should be administered in treatment schedules of 4 or 5 fractions. Similar treatment schedules are suggested for tumors located near the esophagus, but data are more limited. Furthermore, physicians are encouraged to minimize the radiation dose to the esophagus with highly conformal techniques.
  • SBRT is an appropriate option for patients with early-stage tumors that touch the chest wall. The guidelines note that patients should be counseled on the risk of grade 1 and 2 chest wall toxicity. SBRT is also endorsed for tumors that invade the chest wall (cT3).
Use of SBRT as a salvage therapy for patients with medically inoperable, recurrent early-stage disease varies based on treatment history.
 
SBRT is conditionally recommended for carefully selected patients who received prior conventional radiation therapy. However, patients should be counseled on potentially significantly, or even life-threating adverse events.
 
A highly select patient population who had prior SBRT may receive repeat treatment. Limited data exists for this subset of patients and the option is a highly-individualized decision.
 
SBRT may be feasible following limited surgical resections, but the data are limited and physicians should carefully consider patient and disease characteristics on a patient by patient basis, according to a press release.
 
“With longer life expectancies and more sophisticated diagnostic tools, we have seen a rise in the incidence of early-stage lung cancer, including among patients who are not able to undergo surgery or choose not to do so,” said Gregory M. M. Videtic, MD, co-chair of the task force that authored the guideline. “Increasing access to this potentially life-saving treatment is essential to improve outcomes for the growing population of early-stage NSCLC patients.”
 
The guidelines were based on a systematic review of studies published from January 1995 through August 2016. There was a total of 402 abstracts obtained from PubMed.
 
“NSCLC is a complex disease, with a great deal of heterogeneity among patients,” said Megan E. Daly, MD, co-chair of the task force. “This guideline reinforces SBRT as the standard of care for medically inoperable patients, but it also examines the safety and efficacy of SBRT in less traditional clinical scenarios, such as patients with larger tumors or recurrent patients with early-stage diseases.”
 
The guidelines are available as a free access article in Practical Radiation Oncology