Pathologic Complete Response Rate in Neoadjuvant Stereotactic Ablative Radiotherapy Lower Than Expected

Patients who underwent stereotactic ablative radiotherapy (SABR) for medically inoperable early-stage non-small cell lung cancer (NSCLC) had a pathologic complete response (pCR) rate that was lower than expected, according to a study published in JAMA Oncology.

The researchers undertook the study to better understand oncologic and toxicity outcomes from a combined approach to treatment. The 40 patients in this single-arm, phase 2 study, which took place at a tertiary academic cancer center, underwent neoadjuvant SABR followed by surgery. The study recruited patients from September 30, 2014 to August 15, 2017, with follow-up occurring for a median of 19 months. To be eligible for the study, patients needed to have T1T2N0M0 NSCLC and good performance status, along with sufficient pulmonary reserve to undergo surgical resection.

Enrolled patients first were treated with neoadjuvant SABR using a risk-adapted fractionation scheme. Ten weeks later, 35 patients underwent surgery and were evaluated for the primary end point, which was pCR rate as determined by hematoxylin-eosin staining. Results revealed a pCR rate of 60%, and 30- and 90-day postoperative mortality rates were both 0%. There was a 2-year overall survival rate of 77% in patients receiving surgery. In those patients, local control was 100%, regional control was 53%, and distant control was 76%.

Seven patients experienced grade 3 or 4 toxic effects. There was no decline in quality of life after treatment, and during the first year of follow-up there were no significant changes in mean Functional Assessment of Cancer Therapy for Lung–Trial Outcome Index score.

The authors concluded by describing the pCR rate after SABR as “lower than hypothesized.” They added, “The combined approach had toxic effects comparable to series of surgery alone, and there was no perioperative mortality. Further studies are needed to evaluate this combined approach compared with surgical resection alone.”

Reference

Palma DA, Nguyen TK, Louie AV, et al. Measuring the integration of stereotactic ablative radiotherapy plus surgery for early-stage non-small cell lung cancer: a phase 2 clinical trial. JAMA Oncol. 2019 Feb 21. doi: 10.1001/jamaoncol.2018.6993. [Epub ahead of print]