SABR in moderately central NSCLC
SABR to peripheral, small non–small cell lung cancers (NSCLCs) produces high local control rates, with low grade 3-4 toxicity, and is an alternative to resection in patients who are unfit for surgery. In a pragmatic, community-based, prospective cohort experience in Scotland, Robert Rulach, MBChB, and colleagues, treated 50 T1-2N0M0 NSCLC patients with SABR 50-Gy in five fractions (Clin Oncol. 2019 Oct 10. doi: 10.1016/j.clon.2019.09.055). The dose and fractionation schedule was safe and effective in the phase 1/2 RTOG 0813 trial and is concordant with guidelines from the National Comprehensive Cancer Network (NCCN).
All of the tumors were moderately central, as in the RTOG trial. One patient had an additional tumor that was ultracentral. Notably, 84% of patients were deemed medically unfit for surgery.
All patients completed radiotherapy without treatment delays. Two patients died within 90 days of treatment. There were no grade 4 or grade 5 toxicities and the overall rate of grade 3 toxicity was 4%. With a median follow-up of 25.2 months, 34 patients died: 18 from causes unrelated to cancer and 16 from cancer recurrence. The median overall survival was 27 months. The 2-year overall survival rate was 67.6%, commensurate with the rate seen in RTOG 0813.
The researchers concluded that, for frail patients with centrally-located NSCLC treated uniformly in a community practice, SABR with the RTOG 0813 treatment protocol produced acceptable toxicity and overall survival comparable with the published literature.
What this means in clinical practice
The results and conclusions of the study by Dr. Rulach and colleagues are straightforward: SABR can be used for centrally-located NSCLC without producing massive hemoptysis, bronchial stricture, and fistula formation. Since the majority of patients had no histologic diagnosis, T1N0 lesions, and no routine follow-up CT scans beyond 3 months post treatment, conclusions beyond that are unjustified.
In a community-based practice, NCCN guideline–concordant SABR treatment in moderately centrally-located NSCLC was safely delivered. For the burgeoning population of medically inoperable and/or elderly NSCLC patients, this alone is reassuring for clinicians and is helpful information for patients who require and/or desire nonsurgical treatment.
Dr. Lyss has been a community-based medical oncologist and clinical researcher for more than 35 years, practicing in St. Louis. His clinical and research interests are in the prevention, diagnosis, and treatment of breast and lung cancers and in expanding access to clinical trials to medically underserved populations.