Radiation-induced Necrosis Deteriorating Neurological Symptoms andMimicking Progression of Brain Metastasis after Stereotactic-guidedRadiotherapy

Radiation-induced Necrosis Deteriorating Neurological Symptoms and
Mimicking Progression of Brain Metastasis after Stereotactic-guided
Radiotherapy.
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: Cancer Res Treat. 2007 Mar;39(1):16-21. English.
Radiation-induced Necrosis Deteriorating Neurological Symptoms and
Mimicking Progression of Brain Metastasis after Stereotactic-guided
Radiotherapy.

Kim YZ, Kim DY, Yoo H, Yang HS, Shin SH, Hong EK, Cho KH, Lee SH.

Neuro-Oncology Clinic, National Cancer Center, Goyang, Korea.
nslsh@ncc.re.kr
Proton Therapy Center, National Cancer Center, Goyang, Korea.
Department of Pathology, Research Institute and Hospital, National Cancer
Center, Goyang, Korea.

PURPOSE: Although radiation-induced necrosis (RIN) is not a tumor in
itself, the lesion progressively enlarges with mass effects and diffuse
peritumoral edema in a way that resembles neoplasm. To identify the RIN
that mimics progression of brain metastasis, we performed surgical
resections of symptomatic RIN lesions.

Meterials and Methods: From June 2003 to December 2005, 7 patients
received stereotactic-guided radiotherapy (SRT) for metastatic brain
tumor, and they later underwent craniotomy and tumor resection due to the
progressive mass effects and the peritumoral edema that caused focal
neurological deficit. On MR imaging, a ring-like enhanced single lesion
with massive peritumoral edema could not be distinguished from progression
of brain metastasis.

RESULTS: Four patients had non-small cell lung cancer, 2 patients had
colorectal cancer and 1 patient had renal cell carcinoma. The mean tumor
volume was 8.7 ml (range: 3.0~20.7 ml). The prescribed dose of SRT was 30
Gy with 4 fractions for one patient, 18 Gy for two patients and 20 Gy for
the other four patients. The four patients who received SRT with a dose of
20 Gy had RIN with or without microscopic residual tumor cells.

CONCLUSIONS: Early detection of recurrent disease after radiotherapy and
identifying radiation-induced tissue damage are important for delivering
adequate treatment. Therefore, specific diagnostic tools that can
distinguish RIN from progression of metastatic brain tumor need to be
developed.