Neurotoxicity due to prophylactic cranial irradiation for small-cell lung cancer: A retrospective analysis

Prophylactic cranial irradiation (PCI) is an established part of standard therapy for small-cell lung cancer (SCLC). However, the concerns regarding severe late neurotoxicity following PCI have not yet been systematically investigated. Therefore, the aim of this study was to investigate the neurocognitive functioning of SCLC patients treated with PCI. Limited-disease SCLC (LD-SCLC) patients (n=40) treated at Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital (Tokyo, Japan) between January, 2004 and December, 2011 were retrospectively reviewed. A total of 18 LD-SCLC patients were treated with PCI (median age, 65.5 years; range, 52-75 years), whereas 22 LD-SCLC patients did not receive PCI (median age, 65.5 years; range, 57-84 years). The median follow-up for PCI and non-PCI patients was 22 months (range, 4-85 months) and 14.5 months (range, 2-49 months), respectively. Brain metastases occurred in 6 (33%) PCI patients and 11 (50%) non-PCI patients. In the PCI group, dementia occurred in 5 of the 12 PCI patients without brain metastases (42%, 3-40 months after PCI) and in 1 of the 11 non-PCI patients without brain metastases (9%, 4 months after initial treatment). The frequency of dementia in the PCI group was significantly higher compared with that in the non-PCI group (P=0.0357). In the PCI group, all the patients who developed dementia were aged >65 years (range, 66-75 years). Gait disturbance appeared in 25% of the PCI patients without brain metastases (9-27 months after PCI); these patients were also aged >65 years. Patients aged >65 years were significantly more likely to develop dementia (P=0.0028) and gait disturbance (P=0.0291). Therefore, neurotoxicity due to PCI tends to appear more frequently in older patients.