Hippocampal Prophylactic Cranial Irradiation for Small Cell Lung Cancer

-The standard of care in management of small cell lung cancer consists of chemotherapy plus
thoracic radiation followed by prophylactic cranial irradiation (PCI) based on a randomized
trial that demonstrated a significant improvement in overall survival (OS) with PCI.
Unfortunately radiation therapy to the brain is associated with neurocognitive toxicity,
which may be at least in part related to radiation induced injury to neural progenitor cells
in the hippocampus. Both human and animal data suggest an inverse relationship between
radiation dose to the hippocampus and performance on neuropsychological testing. We
hypothesize that hippocampal sparing PCI will allow improved performance on tests of short
term memory and executive function compared to a historical control (RTOG 0212) receiving the
same dose of conventional PCI. The primary objective of this study is to evaluate performance
on the Hopkins Verbal Learning Test-Revised for delayed recall at 6 months following
hippocampal-sparing PCI relative to the historical control. Secondary objectives are to
estimate: 1) composite cognitive function following hippocampal-sparing PCI relative to the
historical control and 2) the rate of metastases in the hippocampus at 2 years following
hippocampal-sparing PCI. The long term goal of this research is to reduce the long term
sequelae of radiation therapy for both primary and metastatic brain tumors.

Inclusion Criteria:

- Patient must have newly diagnosed and confirmed small-cell lung cancer (SCLC)

- Patient must have a performance status of 1 or higher

- Patients must not have received previous irradiation to the brain

- Patients must have limited stage disease with complete response to chemotherapy and
consolidative chest radiotherapy that was documented at least on standard chest x-rays
within one month of study entry

- Negative MRI or CT scan of the brain at least one month before protocol entry

- Women of child-bearing potential must have a negative pregnancy test and also agree to
use adequate contraceptives while on protocol

- Patient must be able to understand and sign the informed consent document

- Patient must be informed of the investigational aspect to this trial prior to singing
the informed consent document

Exclusion Criteria:

- Patients receiving prior external beam irradiation to the head or neck, including any
form of stereotactic irradiation

- Radiographic evidence of brain metastases and/or ipsilateral lung metastases/malignant
pleural effusion

- Planned concurrent chemotherapy or antitumoral agent during PCI

- Concomitant malignancy or malignancy within the past five years other than
nonmelanomatous skin cancer or carcinoma in situ of the cervix

- Patients with minimal pleural effusion evident on chest X-ray; minimal pleural
effusion visible on chest CT is allowed.

- Patients with epilepsy requiring permanent oral medication

_ Patients must not have a serious medical or psychiatric illness that would, in the
opinion of the investigator, prevent informed consent or completion of protocol
treatment, and/or follow-up visits.

- Patients may not take Memantine. This is the only eligibility criterion that has been
added to those of RTOG 0212, since some physicians might now prescribe Memantine. This
medication would not have been given at the time of enrollment on RTOG 0212 and its
administration could confound the results of this study.