Does Number or Volume of Brain Metastases Impact NSCLC Outcomes?

M. Alexander Otto, MMS, PA

December 17, 2021

Key Takeaway

  • After treatment with stereotactic radiosurgery, patients with non-small cell lung cancer (NSCLC) who had 20 or more brain metastases exhibited better local tumor control and similar overall survival compared with patients with only one brain metastasis.

  • Outcomes depend on the cumulative volume of brain lesions, not their number.

  • Authors suggest revising guidelines that currently restrict stereotactic radiosurgery to patients with one to four brain lesions.

Why This Matters

  • Experts continue to debate whether eligibility for stereotactic radiosurgery should be based on the number of brain metastases or their cumulative volume.

  • The new findings suggest that outcomes do not depend on the number of lesions and that restrictions limiting stereotactic radiosurgery to patients with four or fewer metastases should be reconsidered.

Study Design

  • Between 2014 and 2020, 26 patients with NSCLC underwent stereotactic radiosurgery targeting 20 or more brain metastases with a median cumulative tumor volume of 4.52 cm3.

  • Another 56 patients underwent stereotactic radiosurgery for a single brain lesion with a median volume of 4.74 cm3.

Key Results

  • Overall survival was 15 months in patients with 20 or more lesions vs 12 months in patients with only one lesion (P = .3).

  • Two tumors progressed in patients with single lesions (3.6%); in the group with 20 or more lesions, three of 925 lesions (0.3%) progressed (P = .0013).

  • Adverse radiation events did not significantly differ between the group with 20 or more lesions (7.5%) and the single-lesion group (8.7%).


  • The study was a small, nonrandomized review, and the results may not apply to all patients or all types of metastatic cancer.  


  • There was no funding for the study. One investigator holds stock in a maker of stereotactic radiosurgery equipment.

This is a summary of a preprint research report led by Zhishuo Wei at the University of Pittsburgh Medical Center. The full text can be found at

M. Alexander Otto is a physician assistant with a master’s degree in medical science and an award-winning medical journalist who has worked for several major news outlets before joining Medscape. He is an MIT Knight Science Journalism fellow. Email:

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