Akira Matsunobu

Particle radiotherapy for prostate cancer.

Recent advances in external beam radiotherapy have allowed us to deliver higher doses to the tumors while decreasing doses to the surrounding tissues. Dose escalation using high‐precision radiotherapy has improved the treatment outcomes of prostate cancer. Intensity‐modulated radiation therapy has been widely used throughout the world as the most advanced form of photon radiotherapy. In contrast, particle radiotherapy has also been under development, and has been used as an effective and non‐invasive radiation modality for prostate and other cancers. Among the particles used in such treatments, protons and carbon ions have the physical advantage that the dose can be focused on the tumor with only minimal exposure of the surrounding normal tissues. Furthermore, carbon ions also have radiobiological advantages that include higher killing effects on intrinsic radio‐resistant tumors, hypoxic tumor cells and tumor cells in the G0 or S phase. However, the degree of clinical benefit derived from these theoretical advantages in the treatment of prostate cancer has not been adequately determined. The present article reviews the available literature on the use of particle radiotherapy for prostate cancer as well as the literature on the physical and radiobiological properties of this treatment, and discusses the role and the relative merits of particle radiotherapy compared with current photon‐based radiotherapy, with a focus on proton beam therapy and carbon ion radiotherapy.

Dosimetric analysis of upper gastrointestinal ulcer after carbon-ion radiotherapy for pancreatic cancer.

PURPOSE The aim of this study was to clarify the incidence, clinical risk factors, and dose-volume relationship of upper gastrointestinal (GI) ulcer after carbon-ion radiotherapy (C-ion RT) for pancreatic cancer. MATERIALS AND METHODS Fifty-eight pancreatic cancer patients were treated with C-ion RT from April 2014 to December 2015. The total dose was 55.2Gy (RBE) in 12 fractions. D2cm3 of GI tracts were restricted under 46Gy (RBE); RBE-weighted absorbed dose. The association between dosimetric parameters (V10-50, Dmax, D1cm3, D2cm3) and GI ulcer was examined using Spearmans correlation. The incidence of GI ulcer was compared between the two groups divided by the cutoff value. RESULTS Twelve patients (21%) experienced gastric ulcer including only one (2%) grade 3 ulcer. There was no grade 4/5 toxicity or duodenal ulcer. V10-30 was significantly associated with gastric ulcer. The 1-year estimated risk of gastric ulcer for the determined cutoff values were 51% vs. 10% (V10, ⩾102cm(3) or less), 42% vs. 9% (V20, ⩾24cm(3) or less), 34% vs. 4% (V30, ⩾6cm(3) or less). CONCLUSIONS The incidence of GI ulcer after C-ion RT was very low with the dose constraint of D2cm3 <46Gy (RBE). To further minimize the risk of GI ulcer, V10-30 should also be reduced.

Carbon-ion radiotherapy for patients with advanced stage non–small-cell lung cancer at multicenters

ABSTRACT Carbon-ion radiation therapy (CIRT) for advanced non–small-cell lung cancer (NSCLC) has not been well studied to date. This paper aimed to analyze a retrospective multicenter survey for detecting problems with the use of CIRT for Stage II and III NSCLC (7th UICC TNM Staging System). Inclusion was restricted to patients with Stage II and III NSCLC who received CIRT from November 2003 to December 2014. We gathered the data from three CIRT operating centers on July 2015. Patients with radiotherapy history, patients with cancers other than lung cancer, and those receiving palliative therapies were excluded. The patient characteristics, prescribed dose/fraction, survival rates, and adverse effects were analyzed. The total number of patients was 64 (male: 49, female: 15). Of these, 53 patients were medically inoperable. The median age was 76 years (range 46–91), and the median follow-up period was 18.5 months (range 3.2–121.5). The clinical staging consisted of 10 Stage IIA, 30 Stage IIB, 23 Stage IIIA and 1 Stage IIIB. The median prescribed dose was 72.0 Gy (RBE) (range 52.8–72.0) in 16 fractions (range 4–16). The 2-year overall survival, progression-free survival, and local control rates were 62.2% [confidence interval (CI): 47.5–76.9], 42.3% (CI: 28.8–55.8) and 81.8% (CI: 69.9–94.0), respectively. There were no higher than Grade 2 adverse effects observed. CIRT for inoperable Stage II and III NSCLC could be implemented without severe adverse effects, but the clinical staging (including lymph node status) was inhomogeneous. In addition, the prescribed dose and fractionation were not standardized. Further data accumulation and a multiple centers prospective trial for evaluating clinical stage–based results are required.

A single institutional experience of combined carbon-ion radiotherapy and chemotherapy for unresectable locally advanced pancreatic cancer

PURPOSE The aim of this study was to evaluate the efficacy and safety of carbon-ion radiotherapy (C-ion RT) for unresectable locally advanced pancreatic cancer (LAPC). METHODS AND MATERIALS Patients with LAPC treated with definitive C-ion RT between April 2014 and July 2017 were analyzed retrospectively. The prescribed dose was 55.2 Gy (relative biological effectiveness [RBE] weighted absorbed dose) in 12 fractions. Overall survival (OS), local control (LC), progression free survival (PFS), and toxicity were evaluated. RESULTS Sixty-four patients were enrolled. All patients completed planned course of C-ion RT. The median follow-up time for survivors from the initiation of C-ion RT was 24.4 months (range, 5.1-46.1 months). Median survival time was 25.1 months. Two-year OS, LC, and PFS were 53% (95% confidence interval [CI], 39%-66%), 82% (95% CI, 66%-91%), and 23% (95% CI, 14%-36%), respectively. Four patients experienced acute grade 3 toxicities including 3 gastrointestinal (GI) toxicities. There was no grade 3 or more late toxicity. CONCLUSIONS The clinical results of C-ion RT for LAPC at our institution were comparable to those of a recent multi-institutional analysis.

Clinical Experience of SAGA HIMAT

SAGA HIMAT [1], the fourth carbon ion beam therapy facility in Japan, is located in Tosu city, Saga prefecture (Figures 1 and 2). The SAGA HIMAT Project is a collaborative work among the local governments, regional industries, and medical societies in the Kyushu area. The initial cost of this facility was approximately ¥15 billion, which was covered by donations, investments, and local government aid. The facility is managed by a nonprofit organization, SAGA HIMAT Foundation. At SAGA HIMAT [2], carbon ions are accelerated to up to 70% of light speed by 2 linear accelerators and a synchrotron. The accelerated ion beams are transported to treatment rooms A and B. The range of extracted energy is 140 to 400 MeV/u (Table 1). Room A has horizontal and 458 oblique beam lines; room B has horizontal and vertical beam lines. Broad beams are used and each outlet measures 15 cm3 15 cm (Figures 3 and 4). In preparation for treatment, radiation technologists create an immobilization device customized for each patient placed on a mock treatment couch. Dose compensation boluses adjusted to the shape of the irradiation fields are designed from the computed tomography (CT) simulation data and produced by outside manufacturers. We also have a regular CT scanner and magnetic resonance imaging for diagnosis. Treatment room C is now under construction for pencil beam scanning therapy. SAGA HIMAT is a stand-alone outpatient clinic specialized for carbon ion cancer therapy. The patients initially visit a cancer treatment facility of their choice, receive a diagnosis and staging of the cancer, and are referred to our institution for carbon ion