Impact of HA-PCI on self-reported cognitive functioning and brain metastases in small-cell lung cancer: Pooled findings of NCT01780675 and PREMER trials

•Hippocampal avoidance prophylactic cranial irradiation (HA-PCI) is safe.•HA-PCI reduces self-reported cognitive impairment at 4-months.•HA-PCI does not improve longitudinal self-reported cognitive functioning over time.•It is worthwhile to explore the use of HA-PCI further. Cognitive decline is an arising concern in patients who need cranial irradiation. We used the pooled longitudinal individual patient data of two phase III trials: NCT01780675 and PREMER to investigate whether hippocampal avoidance (HA)-PCI is associated with improved self-reported cognitive functioning (SRCF) compared with PCI without increasing brain metastases (BM) development within the HA area. Patients with stage I-IV small cell lung cancer (SCLC) were randomized to PCI or HA-PCI. SRCF was assessed and contrast enhanced brain magnetic resonance imaging (MRI) was performed at baseline and up to 24 months follow-up. SRCF and BM incidence after (HA)-PCI were compared between arms. Self reported cognitive impairment was defined as SCRF