Hiromitsu Iwata

Dr. Hiromitsu Iwata

Department of Radiation Oncology, Nagoya Proton Therapy Center, Nagoya City West Medical Center
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Research Focus & Metrics

Academic Career Length

17Years (2010-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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10 June 2011 in Neuro-Oncology
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Journal Article
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HIHiromitsu Iwata
Hiromitsu Iwata
KSKengo Sato
Kengo Sato
KTKoshi Tatewaki
Koshi Tatewaki
NYNaoki Yokota
Naoki Yokota
MIMitsuhiro Inoue
Mitsuhiro Inoue
YSYuta Shibamoto
Yuta Shibamoto
The aim was to evaluate the clinical outcome of hypofractionated stereotactic radiotherapy (SRT) with CyberKnife for nonfunctioning pituitary adenoma. From October 2000 to March 2009, 100 patients with nonfunctioning pituitary adenoma were treated with hypofractionated SRT. Forty-three patients were male, and 57 were female. The patient's ages ranged from 16 to 82 years (median, 59 years). Five patients were medically inoperable, and 1 refused surgery; the remaining 94 were recurrent cases or those receiving postoperative adjuvant SRT. No patients had a history of previous cranial radiotherapy. Tumor volume ranged from 0.7 to 64.3 mL (median, 5.1 mL). The marginal doses were 17.0 to 21.0 Gy for the 3-fraction schedule and 22.0 to 25.0 Gy for the 5-fraction schedule. Toxicities were evaluated with the Common Terminology Criteria for Adverse Events version 4.0. The median follow-up period for living patients was 33 months (range, 18–118.5 months). The 3-year overall survival and local control rates were 98% and 98%, respectively. In-field and out-field tumor regrowth were observed in 3 and 2 patients, respectively. Transient cyst enlargement occurred in 3 cases. A post-SRT grade 2 visual disorder occurred in 1 patient. Symptomatic post-SRT hypopituitarism was observed in 3 of 74 patients who had not received hormone replacement therapy after surgery. CyberKnife SRT involving 21 Gy in 3 fractions or 25 Gy in 5 fractions is safe and effective for surgical treatment of nonfunctioning pituitary adenoma. Hypofractionated SRT appears useful for protecting the visual nerve and neuroendocrine function, especially for tumors located near the optic pathways and large tumors.

23 August 2011 in Journal of Neuro-Oncology
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Journal Article
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HIHiromitsu Iwata
Hiromitsu Iwata
KTKoshi Tatewaki
Koshi Tatewaki
MIMitsuhiro Inoue
Mitsuhiro Inoue
NYNaoki Yokota
Naoki Yokota
YBYoshimi Baba
Yoshimi Baba
KSKengo Sato
Kengo Sato

14 February 2018 in Cancer Medicine
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Journal Article
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HIHiromitsu Iwata
Hiromitsu Iwata
HIHitoshi Ishikawa
Hitoshi Ishikawa
MTMasaru Takagi
Masaru Takagi
TOTomoaki Okimoto
Tomoaki Okimoto
SMSigeyuki Murayama
Sigeyuki Murayama
HSHideyuki Sakurai
Hideyuki Sakurai
This is the first multi‐institutional retrospective survey of the long‐term outcomes of proton therapy (PT) for prostate cancer in Japan. This retrospective analysis comprised prostate cancer patients treated with PT at seven centers between January 2008 and December 2011 and was approved by each Institutional Review Board. The NCCN classification was used. Biochemical relapse was based on the Phoenix definition (nadir + 2.0 ng/mL). Toxicities were evaluated with the Common Terminology Criteria for Adverse Events version 4.0. There were 215, 520, and 556 patients in the low‐risk, intermediate‐risk, and high‐risk groups, respectively. The median follow‐up period of surviving patients was 69 months (range: 7–107). Among all patients, 98.8% were treated using a conventional fractionation schedule and 1.2% with a hypofractionation schedule; 58.5% and 21.5% received neoadjuvant and adjuvant androgen deprivation therapy, respectively. The 5‐year biochemical relapse‐free survival (bRFS) and overall survival rates in the low‐risk, intermediate‐risk, and high‐risk groups were 97.0%, 91.1%, and 83.1%, and 98.4%, 96.8%, and 95.2%, respectively. In the multivariate analysis, the NCCN classification was a significant prognostic factor for bRFS, but not overall survival. The incidence rates of grade 2 or more severe late gastrointestinal and genitourinary toxicities were 4.1% and 4.0%, retrospectively. This retrospective analysis of a multi‐institutional survey suggested that PT is effective and well‐tolerated for prostate cancer. Based on this result, a multi‐institutional prospective clinical trial (UMIN000025453) on PT for prostate cancer has just been initiated in order to define its role in Japan.

1 May 2016 in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
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Journal Article
Closed access
HIHiromitsu Iwata
Hiromitsu Iwata
HOHiroyuki Ogino
Hiroyuki Ogino
SHShingo Hashimoto
Shingo Hashimoto
MYMaho Yamada
Maho Yamada
HSHiroki Shibata
Hiroki Shibata
YSYuta Shibamoto
Yuta Shibamoto

1 June 2013 in Journal of Thoracic Oncology
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Journal Article
Closed access
HIHiromitsu Iwata
Hiromitsu Iwata
YDYusuke Demizu
Yusuke Demizu
OFOsamu Fujii
Osamu Fujii
KTKazuki Terashima
Kazuki Terashima
MMMasayuki Mima
Masayuki Mima
NFNobukazu Fuwa
Nobukazu Fuwa

1 July 2021 in Cancer Treatment Reviews
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Journal Article
Open access
MMMasashi Mizumoto
Masashi Mizumoto
HFHiroshi Fuji
Hiroshi Fuji
MMMitsuru Miyachi
Mitsuru Miyachi
TSToshinori Soejima
Toshinori Soejima
TYTetsuya Yamamoto
Tetsuya Yamamoto
HSHideyuki Sakurai
Hideyuki Sakurai
Children and adolescents and young adults (AYAs) with cancer are often treated with a multidisciplinary approach. This includes use of radiotherapy, which is important for local control, but may also cause adverse events in the long term, including second cancer. The risks for limited growth and development, endocrine dysfunction, reduced fertility and second cancer in children and AYAs are reduced by proton beam therapy (PBT), which has a dose distribution that decreases irradiation of normal organs while still targeting the tumor. To define the outcomes and characteristics of PBT in cancer treatment in pediatric and AYA patients, this document was developed by the Japanese Society for Radiation Oncology (JASTRO) and the Japanese Society of Pediatric Hematology/Oncology (JSPHO).