A comparison of outcomes after radiosurgery in non-small cell lung cancer patients with one versus more than twenty brain metastases: an international multi-center study.

BACKGROUND

Whether the number or cumulative volume of brain metastases affects survival in patients with metastatic non-small cell lung cancer (NSCLC) remains controversial. We conducted a volume matched multi-center study to determine whether patients with a single metastasis had better outcomes than patients with > 20 brain metastases.

METHODS

Between 2014 and 2022, 317 NSCLC patients (21.14% female; single tumor: 278 patients; >20 tumors, 39 patients) underwent stereotactic radiosurgery (SRS). The prescribed margin dose, cumulative tumor volume, 12 Gy volume, and concurrent systematic disease managements were recorded. The overall survival (OS), local tumor control (LTC), adverse radiation effect (ARE) risk, and new tumor development were compared.

RESULTS

No difference in OS was found between patients with > 20 brain metastases and patients with a single metastasis (p = 0.61). Compared to the single tumor cohort, where 217 of 278 (78.06%) patients had no recorded local tumor progression, patients with > 20 brain metastases had a local tumor control rate of 76.92% (p = 0.25). Patients with > 20 tumors had a significantly higher rate of distant tumor development (69.2%) after SRS compared to patients with single tumors (35.3%; **p = 0.024). No significant difference of ARE rate was found.

CONCLUSION

In this volume matched multi-center study, patients with > 20 tumors showed comparable OS and LTC outcomes compared to patients with single tumors. The number of brain metastases should not be used as a criteria to exclude patients from receiving SRS.