ASTRO Guidelines on Stereotactic Radiation in Early NSCLC

Pam Harrison

June 12, 2017

The American Society for Radiation Oncology (ASTRO) has issued new guidelines on the appropriate use of stereotactic radiation (SBRT) in early-stage non-small cell lung cancer (NSCLC), now the leading cause of cancer-related death for both men and women in the United States.

"Early-stage NSCLC in medically fit patients is traditionally managed surgically," the guideline authors write. "However, many patients are medically inoperable because of comorbidities."

Because conventional radiation is associated with both toxicity and local failure in medically inoperable patients, SBRT has emerged as standard of care for these early-stage patients.

The guideline is published online in Practical Radiation Oncology..

"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," commented co-chair of the ASTRO Task Force, Gregory Videtic, MD, Cleveland Clinic, Ohio.

"SBRT provides an option for these patients...and increasing access to this potentially life-saving treatment is essential to improve outcomes for the growing population of early-stage NSCLC patients," Dr Videtic said in a statement.

Nevertheless, controversy over the use of SBRT remains for patients with large, multifocal, recurrent, or centrally located tumors, as well as for patients who lack tissue confirmation and those with recurrent disease. 

To address these challenging clinical scenarios, guideline authors reviewed the literature and produced a consensus document to guide physicians involved in the management of early-stage NSCLC in their decision-making.

The guideline emphasizes that SBRT is not recommended as an alternative to surgery for patients with stage I NSCLC who are at standard operative risk. For this patient group, lobectomy with systematic mediastinal lymph node evaluation is the recommended procedure of choice.

It adds that SBRT should be discussed as a potential alternative to sublobar resection in patients with stage I NSCLC at high operative risk.

Medically Inoperable Patients

For medically inoperable patients, ASTRO's new recommendations vary according to tumor location, size, and type and treatment history. The guidelines state that:

  • SBRT is appropriate for centrally located tumors, but toxicity risks depend on both the total dose of radiation used and the fractionation schedule. When used, SBRT directed at central tumors should be delivered in 4 or 5 fractions; however, for central tumors deemed to be too high risk for SBRT, hypofractionated radiation therapy, given in 6 to 15 fractions, may be considered.

  • SBRT is also considered to be appropriate for tumors in excess of 5 cm in diameter. As is true for the treatment of central lung tumors, adherence to volumetric and maximum-dose restrictions may help improve the safety profile of SBRT in both groups of patients.

  • In patients who do not have tissue confirmation of a malignant lung nodule — and wherever possible, physicians should try to obtain a biopsy specimen before SBRT — SBRT can be used, but only after a multidisciplinary discussion of this option to ensure that the characteristics of the lesion in question are consistent with a malignant lung nodule.

  • Multiple primary lung cancers (MPLCs) are often difficult to distinguish from intrathoracic metastatic lung cancer, and they need to be evaluated by a multidisciplinary team. Positron emission tomography, computed tomography, or MRI of the brain should be used to help differentiate patients with MPLC from those with intrathoracic metastatic lung cancer. "SBRT may be considered as curative for patients with synchronous MPLC," guideline authors note.

  • Similarly, SBRT may be considered as curative for patients with metachronous MPLCs, even in patients who have previously undergone pneumonectomy and who now have a new primary cancer in their remaining lung.

Again in medically inoperable patients, the new guidelines describe how SBRT may be tailored for use in high-risk scenarios, when, for example, the tumor abuts critical structures, such as the bronchial tree, esophagus, heart, or chest wall.

  •  When close to the proximal bronchial tree, heart, and pericardium, "SBRT should be delivered in 4 to 5 fractions," the guideline authors advise, because serious toxicities to these organs are typically limited.

  • In contrast, physicians need to adhere to the constraints reported in the literature if the tumor is close to the esophagus because severe toxicities can be inflicted on the esophagus upon treatment of tumors in close proximity to it.

  • SBRT also should be offered to patients with T1-2 tumors that abut the chest wall. The authors note that even though toxicity to the chest wall after SBRT treatment is common, it usually resolves with minimal treatment.

  • SBRT may be used in patients with cT3 disease due to chest wall invasion, they add.

The guideline authors also describe a role for SBRT for medically inoperable patients with recurrent early-stage disease. Recommendations again vary according to treatment history.

  • Salvage SBRT may be used after patients have received primary conventionally fractionated radiation, but patient selection for salvage SBRT should be highly individualized. Patients also should be aware of significant — even fatal — toxicities associated with salvage SBRT following conventional radiation.

  • Selecting patients for salvage SBRT after they've undergone a sublobar resection should also be highly individualized.

Dr Videtic has disclosed no relevant financial relationships.

Pract Radiat Oncol. Published online June 12, 2017. Abstract

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