Summary

This phase II/III trial studies whether avoiding the hippocampus during whole-brain radiation therapy prevents cognitive side effects in patients with small cell lung cancer that is found in one lung, the tissues between the lungs, and nearby lymph nodes only (limited stage) or has spread outside of the lung in which it began or to other parts of the body (extensive stage). Radiation therapy uses high energy x-rays to kill tumor cells and shrink tumors. The hippocampus is part of the brain that is important for memory. Avoiding the hippocampus during whole-brain radiation could decrease the chance of side effects on memory and thinking. It is not yet known whether giving whole-brain radiation therapy is more effective with or without hippocampal avoidance in treating patients with small cell lung cancer.

Objectives

PRIMARY OBJECTIVES:
I. Determine whether the 12-month intracranial relapse rate following hippocampal avoidance (HA)-prophylactic cranial irradiation (PCI) is non-inferior to the rate following PCI for patients with small cell lung cancer (SCLC). (Randomized Phase II Component [Non-Inferiority])
II. Determine whether HA-PCI reduces the likelihood of 6-month deterioration from baseline in Hopkins Verbal Learning Test (HVLT)-Revised (R) delayed recall compared to PCI for patients with SCLC. (Phase III Component [Efficacy])

SECONDARY OBJECTIVES:
I. Compare time to cognitive failure, as measured by a battery of tests (HVLT-R, Controlled Oral Word Association [COWA] test, and Trail Making Test [TMT] parts A and B), after PCI versus HA-PCI in SCLC.
II. Compare time to cognitive failure as separately measured by each test (HVLT-R for Total Recall and Delayed Recognition, COWA test, and TMT parts A and B), after PCI versus HA-PCI for SCLC.
III. Compare patient-reported cognitive functioning and other quality of life domains (assessed by the European Organization for Research and Treatment of Cancer [EORTC] Quality of Life Questionnaire [QLQ]-Core [C]30 and Brain Cancer Module [BN] 20) between PCI versus HA-PCI for patients with SCLC.
IV. Compare overall survival after PCI versus HA-PCI for patients with SCLC.
V. Compare 12-month intracranial relapse rate (at completion of phase III) and time to intracranial relapse after PCI versus HA-PCI for patients with SCLC.
VI. Evaluate adverse events according to Common Terminology Criteria for Adverse Events (CTCAE) criteria.
VII. Correlate changes in health-related quality of life (HRQOL) domains with changes in cognitive testing outcomes following PCI versus HA-PCI for patients with SCLC.
VIII. Assess cost-effectiveness of HA-PCI (modulated radiation therapy [MRT]) and PCI (3-dimensional conformal radiation therapy [3DCRT]) using the EuroQOL-5 dimension (D) health state classification (EQ-5D-5L).
IX. Correlate micro-ribonucleic acid (miRNA) signatures with cognitive failure in SCLC patients who received PCI and HA-PCI.
X. Evaluate APOE genotyping as potential predictor of neurocognitive decline, hippocampal atrophy after brain irradiation and/or differential benefit from hippocampal avoidance.
XI. Evaluate baseline MR imaging biomarkers of white matter injury and hippocampal volumetry as potential predictors of cognitive decline and differential benefit from HA-PCI as compared to PCI.

EXPLORATORY OBJECTIVES:
I. Collect serum and whole blood for future translational research analyses.
II. Compare levels of hopefulness between PCI versus HA-PCI for patients with SCLC.
III. Feasibility of remote neurocognitive testing.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients undergo PCI using 3DCRT daily for 2 weeks.

ARM II: Patients undergo PCI with HA using IMRT daily for 2 weeks.

After completion of study treatment, patients are followed every 3 months for 1 year, then every 6 months until 3 years and then annually until death.