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Department of Radiation Oncology

Tetsuo Akimoto, Naoki Nakamura, Sadatomo Zenda, Masakatsu Onozawa, Satoko Arahira, Masamichi Toshima, Atsushi Motegi, Yasuhiro Hirano


Radiotherapy (RT) plays an essential role in the management of cancer patients. It is used as (1) a curative treatment for many patients with locoregional localized malignant disease, (2) integrated therapy combined with chemotherapy and/or surgery, and (3) palliative treatment for patients for whom curative treatment is not a treatment option. In radiotherapeutic approaches, the radiation dose to the loco-regional tumor must be as high as possible, while the dose to the surrounding normal tissues should be kept as low as possible in order to maintain the severity of radiation-related complications within an acceptable level.

The primary aim of the Department of Radiation Oncology is to develop high precision RT such as intensity modulated radiation therapy (IMRT), image-guided radiation therapy (IGRT), stereotactic body RT (SBRT) and proton beam therapy (PBT) and establish the definitive role of RT in cancer treatment. Another important goal is to establish standard treatments for various cancers and optimal irradiation techniques including total dose, fractionation and radiation fields.

Routine activities

At present, the staff of the Radiation Oncology Department consists of seven consultant physicians (radiation oncologists), 19 radiation technologists, four medical physicists, one nurse, and one clerk. We have more than 1,000 new cases for conventional RT and 300 or more new patients for proton beam therapy every year, and quality assurances of both conventional RT and PBT are performed by medical physicists and radiation technologists, and the conference on verification of treatment planning is held every morning in addition to a weekly work conference regarding research activities. RT and PBT are routinely based on three-dimensional radiation therapy planning and PBT using RT-dedicated multi-detector-row helical computed tomography (CT) scanning in order to confirm a precise radiation dose to the targeted tumors. Respiratory-gating has been applied especially in radiotherapeutic management for patients with lung, esophagus and liver cancers.

Selection of treatment approaches is determined through clinical conferences between radiation oncologists, surgical oncologists and medical oncologists. Many clinical trials involving RT as the sole or combined treatment modalities for various cancers are now in progress.

The section is responsible for conventional (photon-electron) RT that consists of 4 linear accelerators, a CT simulator, four treatment planning computer workstations, and other important devices. IMRT and IGRT have been routinely applied for head and neck cancer and prostate cancer. The section is also responsible for PBT that is composed of seven operating staff members and one technician for fabricating the compensator and aperture; they are sent from manufacturing companies and work in collaboration with the other staff members of the Department. PBT consists of two treatment rooms and both rooms are routinely used for rotational gantry treatment. The Department ensures quality assurance and regular maintenance of the PBT machines for precise dose delivery and safe treatment.

Research activities

In the Radiation Oncology Department, the following research activities are in progress:

  1. Establishment of optimal combined approaches including RT and chemotherapy for locally advanced head and neck cancer, non-small cell lung cancer and esophageal cancer, and so on.
  2. Establishment of clinical usefulness of IMRT for head and neck cancer, localized prostate cancer and cervical esophageal cancer.
  3. Hypofractionated IMRT for localized prostate cancer.
  4. Hypofractionated PBT for localized prostate cancer.
  5. Evaluation of feasibility of PBT combined with chemotherapy for inoperable locally advanced non-small cell lung cancer and locally advanced esophageal cancer.
  6. Evaluation of long-term complications after PBT for pediatric malignancies.
  7. The role of gene polymorphism in development of acute and late radiation-related complications.
  8. Exploration of biomarkers for head and neck cancer.
  9. Radiobiological investigation of cellular response to radiation and proton beam.

Clinical trials

The following in-house and multiinstitutional clinical trials are in progress:

  1. The Japan Clinical Oncology Group (JCOG) 0701: Accelerated fractionation vs. conventional fractionation radiation therapy for glottic cancer of T1-2N0M0 phase III study.
  2. JCOG0701-A1: Evaluation of single-nucleotide polymorphisms (SNPs) in development of acute and late complications after accelerated fractionation and/or conventional fractionation radiation therapy for glottic cancer of T1-2N0M0.
  3. JCOG1015: A phase II study of intensity modulated radiation therapy (IMRT) with chemotherapy for loco-regionally advanced nasopharyngeal cancer (NPC).
  4. Phase II study of PBT for malignant melanoma of nasal cavity.
  5. Phase II trial of concurrent chemoradiotherapy with 5-FU plus cisplatin for resectable squamous cell carcinoma of cervical esophagus.
  6. The Japanese Radiation Oncology Study Group (JROSG) phase II trial of IMRT with concurrent chemoradiotherapy for resectable squamous cell carcinoma of cervical esophagus.
  7. JCOG1208: A non-randomized confirmatory study of intensity modulated radiation therapy (IMRT) for T1-2N0-1M0 oropharyngeal cancer.
  8. JCOG1008: Phase II/III trial of postoperative chemoradiotherapy comparing 3-weekly cisplatin with weekly cisplatin in high-risk patients with squamous cell carcinoma of head and neck
  9. Dose escalation study of PBT combined with concurrent chemotherapy for locally advanced esophageal cancer.
  10. JCOG1408: Phase III study of SBRT for stage I non-small cell lung cancer.


We established education and training systems for residents and junior radiation oncologists through clinical conferences and lectures on radiation oncology, physics and radiation biology. In addition, a training course about quality assurance of radiation therapy has been regularly held for medical physicists and radiological technologists.

Future prospects

We are now aiming at the establishment of a system that can provide high-quality and safe high-precision radiation therapy. In addition, we would like to promote research and development of innovative technologies regarding radiation therapy, radiation biology and medical physics.

Table 1. Number of patients treated with radiation therapy during 2011-2015

List of papers published in 2015


  1. Tahara M, Kiyota N, Mizusawa J, Nakamura K, Hayashi R, Akimoto T, Hasegawa Y, Iwae S, Monden N, Matsuura K, Fujii H, Onozawa Y, Homma A, Kubota A, Fukuda H, Fujii M. Phase II trial of chemoradiotherapy with S-1 plus cisplatin for unresectable locally advanced head and neck cancer (JCOG0706). Cancer Sci, 106:726-733, 2015
  2. Hotta K, Kohno R, Nagafuchi K, Yamaguchi H, Tansho R, Takada Y, Akimoto T. Evaluation of monitor unit calculation based on measurement and calculation with a simplified Monte Carlo method for passive beam delivery system in proton beam therapy. J Appl Clin Med Phys, 16:228-238, 2015
  3. Mizowaki T, Aoki M, Nakamura K, Yorozu A, Kokubo M, Karasawa K, Kozuka T, Nakajima N, Sasai K, Akimoto T. Current status and outcomes of patients developing PSA recurrence after prostatectomy who were treated with salvage radiotherapy: a JROSG surveillance study. J Radiat Res, 56:750-756, 2015
  4. Hashimoto Y, Akimoto T, Iizuka J, Tanabe K, Mitsuhashi N. Correlation between the changes in the EPIC QOL scores and the dose-volume histogram parameters in high-dose-rate brachytherapy combined with hypofractionated external beam radiation therapy for prostate cancer. Jpn J Clin Oncol, 45:81-87, 2015
  5. Motegi A, Kawashima M, Arahira S, Zenda S, Toshima M, Onozawa M, Hayashi R, Akimoto T. Accelerated radiotherapy for T1 to T2 glottic cancer. Head Neck, 37:579-584, 2015
  6. Zenda S, Ishi S, Akimoto T, Arahira S, Motegi A, Tahara M, Hayashi R, Asanuma C. DeCoP, a Dermatitis Control Program using a moderately absorbent surgical pad for head and neck cancer patients receiving radiotherapy: a retrospective analysis. Jpn J Clin Oncol, 45:433-438, 2015
  7. Zenda S, Kawashima M, Arahira S, Kohno R, Nishio T, Tahara M, Hayashi R, Akimoto T. Late toxicity of proton beam therapy for patients with the nasal cavity, para-nasal sinuses, or involving the skull base malignancy: importance of long-term follow-up. Int J Clin Oncol, 20:447-454, 2015