Neurocognitive function in patients with small cell lung cancer : effect of prophylactic cranial irradiation

The use of prophylactic cranial irradiation (PCI) in patients with small cell lung cancer (SCLC) has been tempered by fears of detrimental effects on cognitive function. Neuropsychologic testing was prospectively conducted before and after PCI to evaluate its effects on cognitive function in patients with SCLC.

Ninety-six patients who completely or partially responded to initial therapy underwent formal neurocognitive testing before PCI. Three patients who had central nervous system metastasis were excluded. Of the remaining patients, 69 received PCI (mean dose, 25 grays [Gy] in 10 fractions). Repeat testing was performed on 37 patients (median follow-up, 23 months; range, 6-120 months).

Baseline impairment was defined as > or =1.5 standard deviations below the normative mean. Before undergoing PCI, 47% of patients had evidence of impaired cognitive function. After PCI, univariate analysis revealed significant transient declines in executive function (pre-PCI mean, 15.6 +/- 11.5; post-PCI, 27.1 +/- 17.6 [P = .008]) and language (pre-PCI mean, 33.8 +/- 9.9; post-PCI, 31.0 +/- 9.0 [P = .049]) at early timepoints. Controlling for noncentral nervous system disease progression the deficit in executive function was no longer significant. Moreover, these deficits were not sustained, and significant improvements in language and motor coordination were recorded. On multivariate analysis, no significant differences before and after PCI were found.

Neurocognitive testing demonstrated that a substantial portion of patients with SCLC had impaired brain functioning at baseline. Persistent declines in cognitive function were not observed after cranial irradiation. These data do not favor the omission of PCI on the basis of fears of neurotoxic effects.