EVALUATION OF COGNITIVE FUNCTION IN PATIENTS WITH LIMITED SMALL-CELL LUNG-CANCER PRIOR TO AND SHORTLY FOLLOWING PROPHYLACTIC CRANIAL IRRADIATION

Purpose: Cognitive deficits after treatment for small cell lung cancer (SCLC) have been attributed to prophylactic cranial irradiation (PCI). A prospective study of neuropsychological function was undertaken to document the evolution and magnitude of neuropsychologic deficits. Methods and Materials: Thirty patients with limited stage SCLC who responded well (29 complete response (CR), 1 partial response (PR)) to combination chemotherapy plus thoracic irradiation or resection were studied with neuropsychological rests in the cognitive domains of intelligence, frontal lobe function, language, memory, visual-perception, and motor dexterity prior to a planned course of PCT. Nine patients had a neurologic history that could influeuce testing. Results: An unexpected 97% (29 out of 30) of patients had evidence of cognitive dysfunction prior to PCT. The most frequent impairment was verbal memory, followed by frontal lobe dysfunction, and fine motor incoordination. Of the patients with no prior neurologic or substance abuse history, 20 out of 21 (95%) had impairments on neuropsychological assessment. This neurologically normal group was just as impaired as the group with such a history with respect to delayed verbal memory and frontal lobe executive function. Eleven patients had neuropsychological testing 6 to 20 months after PCI; no significant differences were found from their pretreatment tests. Conclusions: A high proportion of neurologically normal patients with limited SCLC and favorable responses to combination chemotherapy have specific cognitive deficits before receiving PCI. Short-term (6 to 20 months) observations after PCI have shown no significant deterioration.