Aggressive Treatment Leads to Long-Term Survival in Low-Risk Stage IV NSCLC

Allison Ashworth, MD

Timing of metastatic development, lymph node involvement, and type of disease all factor into the overall survival (OS) rate of patients with stage IV non-small cell lung cancer (NSCLC), and could offer a potential risk stratification scheme for ablative therapy, according to a meta-analysis presented at the ASTRO 56th Annual Meeting.

The analysis looked at data from 757 patients from 20 hospitals worldwide and found that aggressively treating “low-risk” patients with NSCLC, those with metachronous metastases, with surgery or stereotactic ablative radiotherapy (SABR) elicited a 5-year OS rate of 47.8%. The OS rate was 36.2% for intermediate-risk patients and 13.8% for high-risk. Among all patients, median OS was 26 months, median PFS was 11 months, and 5-year OS was 29.4%.

“We hope our study’s results will help determine which stage IV NSCLC patients are most likely to benefit from aggressive treatments, and equally as important, help identify those patients most likely to fail, thus sparing them from futile and potentially harmful treatments,” lead study author Allison Ashworth, MD, a radiation oncologist who completed the study as part of her training at Western University in London, Ontario, said in a statement.

In the trial, patients were stratified based on timing of metastatic development (synchronous versus metachronous, P < 0.001), lymph node involvement (P = 0.002), and adenocarcinoma histology (P = 0.036). Low-risk patients (n = 146) were defined as those with metachronous metastases while intermediate-risk patients (n = 201) had synchronous metastases and no evidence of involved lymph nodes in the chest. High-risk (n = 184) patients were defined as those with synchronous metastases and evidence of lymph node involvement in the chest.

Patients were treated with surgical metastectomy, SABR, stereotactic radiosurgery or radical external-beam radiotherapy, and curative-intent treatment of the primary lung cancer. Surgery was the most commonly used treatment for both the primary tumor and metastases (83.9%). Despite aggressive treatment, more than half of all patients in the analysis progressed in previously treated areas or developed new disease sites within 1 year.

OS Rate by Risk With Aggressive Treatment

Population

Patients

Risk Factors

OS Rate

Low-risk

146

Metachronous metastases

47.8%

Intermediate-risk

201

Synchronous metastases, no evidence of involved lymph nodes in the chest

36.2%

High-risk

184

Synchronous metastases, evidence of lymph node involvement in the chest

13.8%

Total

757

-

29.4%

Ashworth noted that patients in this analysis were “a very select minority of stage IV patients who are younger, more physically fit, with a lower burden and slower pace of disease than the average stage IV patient.”

As a retrospective analysis, the true impact of aggressive treatment still needs to be determined in a randomized trial. However, this risk classification scheme could be utilized in guiding the selection of patients for future studies of ablative treatment, the authors of the study noted.

“We must await the results of randomized clinical trials to answer this question,” Ashworth said. “In the meantime, it is our hope that our study will help cancer specialists in making treatment decisions and in the development of clinical trials.”

Ashworth A, Senan S, Palma DA, et al. An Individual Patient Data Meta-Analysis of Outcomes and Prognostic Factors after Treatment of Oligometastatic Non-Small Cell Lung Cancer. Presented at: 2014 ASTRO Annual Meeting; September 14-17, 2014; San Francisco, CA. Presentation Number: 168.

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