Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: Takashi Yamamoto x
  • By Author: Hasegawa, Toshinori x
Clear All Modify Search
Restricted access

Toshinori Hasegawa, Yoshihisa Kida, Takenori Kato, Hiroshi Iizuka and Takashi Yamamoto


Gamma Knife surgery (GKS) has been a safe and effective treatment for small- to medium-sized vestibular schwannomas (VSs) over relatively long-term outcomes. However, even with recent radiosurgical techniques, hearing results following GKS remain unsatisfactory. The purpose of this study was to evaluate the hearing preservation rate as well as factors related to hearing preservation in patients with VSs and serviceable hearing who were treated with GKS.


Among patients with Gardner-Robertson (GR) Class I or II serviceable hearing and VSs treated with GKS between 1991 and 2009, 117 were evaluable via periodic MR imaging and audiometry.


The median age at the time of GKS was 52 years. Four patients (3%) had undergone prior surgery. Fifty-six patients (48%) had GR Class I hearing and 61 (52%) had GR Class II hearing at the time of GKS. The median tumor volume was 1.9 cm3. The median maximum and tumor margin radiation doses were 24 and 12 Gy, respectively. The median follow-up periods for MR imaging and audiometry were 74 and 38 months, respectively. The overall tumor control rate was 97.5%. Actuarial 3-, 5-, and 8-year hearing preservation rates were 55%, 43%, and 34%, respectively. On multivariate analysis, GR hearing class at the time of GKS and the mean cochlear dose affected hearing preservation significantly. In a limited number of patients who were treated using the most recent dose planning techniques and who had GR Class I hearing before treatment, the 3- and 5-year hearing preservation rates increased to 80% and 70%, respectively.


For the majority of patients with small- to medium-sized VSs, GKS was an effective and reasonable alternative to resection with satisfactory long-term tumor control. Factors related to hearing preservation included a GR Class I hearing pre-GKS and a lower mean cochlear radiation dose. To retain serviceable hearing, it is important to apply GKS treatment while patients retain GR Class I hearing.

Restricted access

Toshinori Hasegawa, Yoshihisa Kida, Takenori Kato, Hiroshi Iizuka, Shunichiro Kuramitsu and Takashi Yamamoto


Little is known about long-term outcomes, including tumor control and adverse radiation effects, in patients harboring vestibular schwannomas (VSs) treated with stereotactic radiosurgery > 10 years previously. The aim of this study was to confirm whether Gamma Knife surgery (GKS) for VSs continues to be safe and effective > 10 years after treatment.


A total of 440 patients with VS (including neurofibromatosis Type 2) treated with GKS between May 1991 and December 2000 were evaluable. Of these, 347 patients (79%) underwent GKS as an initial treatment and 93 (21%) had undergone prior resection. Three hundred fifty-eight patients (81%) had a solid tumor and 82 (19%) had a cystic tumor. The median tumor volume was 2.8 cm3 and the median marginal dose was 12.8 Gy.


The median follow-up period was 12.5 years. The actuarial 5- and ≥ 10-year progression-free survival was 93% and 92%, respectively. No patient developed treatment failure > 10 years after treatment. According to multivariate analysis, significant factors related to worse progression-free survival included brainstem compression with a deviation of the fourth ventricle (p < 0.0001), marginal dose ≤ 13 Gy (p = 0.01), prior treatment (p = 0.02), and female sex (p = 0.02). Of 287 patients treated at a recent optimum dose of ≤ 13 Gy, 3 (1%) developed facial palsy, including 2 with transient palsy and 1 with persistent palsy after a second GKS, and 3 (1%) developed facial numbness, including 2 with transient and 1 with persistent facial numbness. The actuarial 10-year facial nerve preservation rate was 97% in the high marginal dose group (> 13 Gy) and 100% in the low marginal dose group (≤ 13 Gy). Ten patients (2.3%) developed delayed cyst formation. One patient alone developed malignant transformation, indicating an incidence of 0.3%.


In this study GKS was a safe and effective treatment for the majority of patients followed > 10 years after treatment. Special attention should be paid to cyst formation and malignant transformation as late adverse radiation effects, although they appeared to be rare. However, it is necessary to collect further long-term follow-up data before making conclusions about the long-term safety and efficacy of GKS, especially for young patients with VSs.

Free access

Takuya Kawabe, Masaaki Yamamoto, Yasunori Sato, Shoji Yomo, Takeshi Kondoh, Osamu Nagano, Toru Serizawa, Takahiko Tsugawa, Hisayo Okamoto, Atsuya Akabane, Kazuyasu Aita, Manabu Sato, Hidefumi Jokura, Jun Kawagishi, Takashi Shuto, Hideya Kawai, Akihito Moriki, Hiroyuki Kenai, Yoshiyasu Iwai, Masazumi Gondo, Toshinori Hasegawa, Soichiro Yasuda, Yasuhiro Kikuchi, Yasushi Nagatomo, Shinya Watanabe and Naoya Hashimoto


In 1999, the World Health Organization categorized large cell neuroendocrine carcinoma (LCNEC) of the lung as a variant of large cell carcinoma, and LCNEC now accounts for 3% of all lung cancers. Although LCNEC is categorized among the non–small cell lung cancers, its biological behavior has recently been suggested to be very similar to that of a small cell pulmonary malignancy. The clinical outcome for patients with LCNEC is generally poor, and the optimal treatment for this malignancy has not yet been established. Little information is available regarding management of LCNEC patients with brain metastases (METs). This study aimed to evaluate the efficacy of Gamma Knife radiosurgery (GKRS) for patients with brain METs from LCNEC.


The Japanese Leksell Gamma Knife Society planned this retrospective study in which 21 Gamma Knife centers in Japan participated. Data from 101 patients were reviewed for this study. Most of the patients with LCNEC were men (80%), and the mean age was 67 years (range 39–84 years). Primary lung tumors were reported as well controlled in one-third of the patients. More than half of the patients had extracranial METs. Brain metastasis and lung cancer had been detected simultaneously in 25% of the patients. Before GKRS, brain METs had manifested with neurological symptoms in 37 patients. Additionally, prior to GKRS, resection was performed in 17 patients and radiation therapy in 10. A small cell lung carcinoma–based chemotherapy regimen was chosen for 48 patients. The median lesion number was 3 (range 1–33). The median cumulative tumor volume was 3.5 cm3, and the median radiation dose was 20.0 Gy. For statistical analysis, the standard Kaplan-Meier method was used to determine post-GKRS survival. Competing risk analysis was applied to estimate GKRS cumulative incidences of maintenance of neurological function and death, local recurrence, appearance of new lesions, and complications.


The overall median survival time (MST) was 9.6 months. MSTs for patients classified according to the modified recursive partitioning analysis (RPA) system were 25.7, 11.0, and 5.9 months for Class 1+2a (20 patients), Class 2b (28), and Class 3 (46), respectively. At 12 months after GKRS, neurological death–free and deterioration–free survival rates were 93% and 87%, respectively. Follow-up imaging studies were available in 78 patients. The tumor control rate was 86% at 12 months after GKRS.


The present study suggests that GKRS is an effective treatment for LCNEC patients with brain METs, particularly in terms of maintaining neurological status.