As reviewed in this issue of The ASCO Post, a recent ASCO panel, chaired by Bryan Schneider, MD, and Brendon Stiles, MD, has provided an endorsement of a recently published guideline on the use of stereotactic body radiotherapy for non–small cell lung cancer.1 The original guideline,2 developed and written by a panel from the American Society for Radiation Oncology (ASTRO), provides guidance on the use of stereotactic body radiotherapy for challenging clinical scenarios, including centrally located tumors, large (> 5 cm) tumors, multifocal tumors, and previously irradiated tumors. It also addresses the use of stereotactic body radiotherapy for medically operable patients and in patients without tissue confirmation.
As stereotactic body radiotherapy has been widely and rapidly implemented in radiation oncology practice, the ASTRO guideline provides a valuable resource for physicians adopting this technology. ASCO’s endorsement helps make this guideline available to a broader audience and provides valuable additional commentary, particularly for physicians in non–radiation oncology specialties.
Medically Operable Patients: Surgery Remains Standard of Care
Both the ASTRO and ASCO panels recommend that patients should be assessed for surgical suitability by a thoracic surgeon and that multidisciplinary discussions are encouraged. The guideline makes the distinction between patients at standard operative risk and those at “high” operative risk—a population lacking a clear definition but for whom sublobar resections are frequently considered in lieu of lobectomy. For patients at standard operative risk, stereotactic body radiotherapy is not recommended outside the setting of a clinical trial, although discussions about stereotactic body radiotherapy
The guideline and endorsement reflect uncertainty as to the comparative effectiveness of stereotactic body radiotherapy and surgical resection for early-stage lung cancer, due to the lack of completed randomized trials.— Megan E. Daly, MD
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may be appropriate in a multidisciplinary setting. Among patients at high operative risk, discussions about stereotactic body radiotherapy are encouraged, acknowledging the paucity of long-term (> 3 year) outcomes data.
The guideline and endorsement reflect uncertainty as to the comparative effectiveness of stereotactic body radiotherapy and surgical resection for early-stage lung cancer, due to the lack of completed randomized trials. Multiple well-designed randomized efforts, including ROSEL, STARS, and ACOSOG Z0499, have all closed early secondary to poor accrual. Ultimately, successful accrual to ongoing efforts, including the Veterans Affairs’ VALOR study and the JoLT-Ca STABLE-MATES consortium trial, is critical.
Challenge of Radiographic Diagnosis
One of the potentially controversially components of the -ASTRO guideline and ASCO endorsement is the recommendation that stereotactic body radiotherapy may be offered in select scenarios to patients lacking tissue confirmation of malignancy. Although the guideline strongly recommends obtaining tissue whenever possible, it addresses the increasing common scenario of the frail patient for whom the procedures to obtain tissue pose prohibitive risk. In such cases, the ASTRO guideline and ASCO endorsement recommend multidisciplinary review to ensure the tumor is -radiographically and clinically consistent with early-stage lung cancer and informed consent/shared decision-making with patients to ensure they understand the small risk of treatment of a nonmalignant process. Although a break with the traditional oncologic orthodoxy of never treating without tissue, the guideline and endorsement appropriately recognize that lung stereotactic body radiotherapy is a somewhat unique scenario in which the risks of biopsy may outweigh the risks of a curative-intent therapy and appropriately do not insist on denying this therapy to patients with prohibitive biopsy risks.
Balancing Tumor Control and Toxicity
A consistent theme in both the original ASTRO guideline and the ASCO endorsement is providing an appropriate balance between tumor control and risk of toxicity. When delivered appropriately to peripherally located tumors, stereotactic body radiotherapy carries a relatively low risk of side effects and long-term toxicities. However, for some of the challenging scenarios tackled in this guideline, such as central tumors abutting the airways or esophagus as well as previously irradiated tumors, risks may be considerably higher. Both the ASTRO guideline and ASCO endorsement acknowledge that for medically inoperable patients, limited treatment options are available and that acceptance of a somewhat higher risk profile may be acceptable following informed consent and shared decision-making. Other treatments, including hypofractionated and conventionally fractionated radiation, should also be considered and discussed. The theme of shared decision-making with patients is appropriately highlighted throughout the guideline and the endorsement.
Closing Thoughts
Both the ASTRO guideline and ASCO endorsement, which contains additional commentary, provide a valuable resource for all specialists involved in the treatment of lung cancer. The guideline highlights the crucial importance of shared patient decision-making with a focus on goals of care and multidisciplinary input and decision-making. A number of key questions had relatively limited clinical data available from which to generate recommendations, highlighting the crucial importance of ongoing clinical trials in patients with early-stage lung cancer. Enrollment of patients to such trials, as well as to prospective registries, is strongly endorsed. ■
Dr. Daly is Associate Professor of Radiation Oncology at the University of California, Davis.
DISCLOSURE: Dr. Daly reported no conflicts of interest.
REFERENCES
2. Videtic GMM, Donington J, Giuliani M, et al: Stereotactic body radiation therapy for early-stage non-small cell lung cancer: Executive Summary of an ASTRO evidence-based guideline. Pract Radiat Oncol 7:295-301, 2017.
