Risk factors for type I leptomeningeal metastasis derived from non-small cell lung cancer and the impact of treatment for brain metastases on its development.

BACKGROUND

Preventing Type I leptomeningeal metastasis (LM) is critical when treating brain metastases (BMs). The aim of this study was to extract risk factors for Type I LM and to clarify the optimal treatment for BMs from the perspective of Type I LM prevention.

METHODS

The clinical course of consecutive cases of BMs derived from non-small cell lung cancer (NSCLC) treated at our hospital was retrospectively evaluated. The relationship between clinicopathological factors, including molecular background, and Type I LM development was verified. In addition, the difference in the time to Type I LM because of treatment for BMs was evaluated to clarify the effectiveness of each treatment in preventing Type I LM.

RESULTS

Of 784 patients with BMs, 44 exhibited Type I LM at the onset of BMs. Poor performance status ( < .0001) and mutated epidermal growth factor receptor () gene ( = .004) were significant risk factors for Type I LM. Among the 740 patients without LMC at diagnosis, 85 developed Type I LM. Younger age ( = .011) and mutated ( < .0001) were risk factors for developing LMC after BMs. Osimertinib reduced the incidence of Type I LM (hazard ratio [HR]: 0.48; 95% confidence interval [CI]: 0.24-0.97) in -mutated cases. Immune checkpoint inhibitors (ICIs) showed a tendency to prolong the time to Type I LM (HR: 0.15; 95% CI: 0.02-1.11) in -wild-type cases.

CONCLUSIONS

Patients with -mutated NSCLC are prone to developing Type I LM. Osimertinib for -mutated cases and ICIs are expected to prevent Type I LM after the diagnosis of BMs.