The effect of hippocampal sparing during prophylactic cranial irradiation on the preservation of neurocognitive functions in patients with small cell lung cancer: a preliminary study

Summary: Prophylactic cerebral irradiation (PCI) is the standard of care for patients with limited small cell lung cancer (SCLC). Cerebral irradiation is associated with deterioration of patients' quality of life in terms of cognitive function, in which hippocampus plays a critical role. Protection of the hippocampus during PCI aims to reduce the adverse effects of ionizing radiation on neurocognitive function, which may be important for optimal quality of life. To date, subjective psychological tests have been used as a methodical assessment of cognitive function in patients after PCI. In the present study, we attempted to evaluate the effect of hippocampal sparing during PCI on the preservation of cognitive functions in patients with SCLC, using two diagnostic and screening tests: Mini-Mental State Examination (MMSE) Short Scale and Montreal Cognitive Assessment (MoCA) Scale. Assessment was made at three time points: before start of radiation, immediately after completion of irradiation and 3 months after radiation therapy. Our results indicate, that after radiation therapy there is a deterioration in cognitive functions. We additionally found, that the results of both tests after radiation therapy differed significantly according to the gender and education of patients. Following PCI, cognitive functions deteriorate in SCLC patients, even when radiation doses are reduced in the hippocampal area. This trend persists at least 3 months after the end of brain irradiation.