Staged gamma knife radiosurgery for metastatic brain tumors

Atsuya Akabane1, Itaru Kanazawa2, Akio Morita3, Chikayuki Ochiai3

1Tokyo, Japan 2Gamma Knife Center, NTT Medical Center Tokyo, Tokyo, Japan 3Department of Neurosurgery, NTT Medical Center Tokyo, Tokyo, Japan

Keywords: gamma knife, radiosurgery, brain metastasis, technique, outcome

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     Surgical resection, if feasible, is recommended for patients with large metastatic brain tumors (METs). However, it is a burden to an advanced cancer patient with a limited survival period. 
     Therefore, we performed staged gamma knife radiosurgery (GKS) for relatively large METs that are difficult to manage by conventional GKS. Here, we report preliminary results of the staged GKS.
     We retrospectively analyzed 26 patients who underwent staged GKS at our hospital since 2007 for METs with a tumor volume of more than 8ml. The median age of the patients was 66 years (range, 41-86 years) and the median tumor volume at initial GKS was 10.6 ml (range, 8.9-28.3 ml).
      The primary lesions were lung cancer in 11 patients, cancer of the gastrointestinal tract in 10 patients, and other cancers in 5 patients. According to the method reported by Higuchi et al., staged GKS was principally performed 3 times every 2 weeks (3-staged group). The median prescription and central dose in each treatment were 10 Gy (range, 8-10 Gy) and 15 Gy (range, 11-18 Gy), respectively. In 9 patients with a survival period of 6 months or less, staged GKS was performed 2 times in a 2-week interval to shorten the treatment period (2-staged group). In these patients, the median prescription and central dose in each treatment were 13 Gy (range, 12-14 Gy) and 21 Gy (range, 19-26 Gy), respectively. The median follow-up period was 6 months (range, 1-29 months).
     The tumor volume at the final treatment in the 3-staged group and the 2-staged group showed an average reduction of 34% and 19%, respectively, compared to that at the initial treatment. Of the 17 symptomatic patients, 11 (65%) showed a rapid improvement in the Karnofsky performance score and reduction in tumor volume within the treatment period (2-4 weeks). The median survival time was 10.5 months, and local tumor control was achieved in 18 patients (70%). Symptomatic radiation-induced adverse effect was not observed.
     This was a retrospective review.
     Although our results are preliminary, they suggest that staged GKS may be effective for relatively large METs even in the case of advanced cancer patients.
     These results need to be compared to single stage procedure where lower doses might be given.


Project Roles:

A. Akabane (), I. Kanazawa (), A. Morita (), C. Ochiai ()