Risk of hippocampal metastases in small cell lung cancer patients at presentation and after cranial irradiation: a safety profile study for hippocampal sparing during prophylactic or therapeutic cranial irradiation.
OBJECTIVE
Neurocognitive impairment (NI) in patients with small cell lung cancer (SCLC) after whole brain radiation treatment (WBRT) is a significant cause of morbidity. Hippocampal avoidance (HA) during WBRT may mitigate or prevent NI in such patients. However, this has not been tested in SCLC patients. The estimated risk of metastases in the HA region (HM) in patients with SCLC at diagnosis or after WBRT is unknown. Our study aimed to determine the risk of HM in patients with SCLC and to assess correlated clinical factors.


METHODS
Patients with SCLC who experienced brain metastases (BM) at presentation (de novo) or after WBRT treated at the Saskatoon Cancer Centre between 2005 and 2012 were studied. Relevant neuroimaging was independently reviewed by a neuroradiologist. HM was defined as metastases within 5 mm of the hippocampus. Logistic regression analysis was performed to assess correlation between various clinical variables and HM.


RESULTS
Seventy eligible patients were identified. Of 59 patients presenting with de novo BM, 3 patients (5%, 95% confidence interval [CI]: 0%-10.7%) had HM. Collectively there were 359 (range, 1-33) de novo BM with 3 (0.8%, 95% CI: 0%-1.7%) HM deposits. Twenty patients experienced progression of metastatic disease in the brain after WBRT. Of the 20 patients, only 1 patient (5%, 95% CI: 0%-14.5%) experienced HM. On logistic regression, no factors significantly correlated with HM.


CONCLUSIONS
The overall incidence of HM before or after WBRT in SCLC patients is low, providing preliminary support for the safety of HA during planned clinical trials of HA-WBRT for SCLC.
Saskatoon Cancer Center, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Electronic address: Vijayananda.kundapur@saskcancer.ca.
Vijayananda
V
Kundapur
Department of Radiology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Tasha
T
Ellchuk
Saskatoon Cancer Center, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Shahid
S
Ahmed
Cadence Health Brain Tumor Center and Cadence Health Proton Center, Chicago, Illinois.
Vinai
V
Gondi
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000175:diagnosis / Q000532:radiotherapy* / Q000556:secondary*; D016371:Cranial Irradiation / Q000009:adverse effects / Q000379:methods*; D018450:Disease Progression; D005260:Female; D006624:Hippocampus / Q000528:radiation effects*; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000175:diagnosis; D059351:Organ Sparing Treatments / Q000009:adverse effects / Q000379:methods*; D055752:Small Cell Lung Carcinoma / Q000175:diagnosis / Q000532:radiotherapy* / Q000556:secondary*