Publications by authors named "Koji Masui"

Background: The present study investigated the acute mucosal reaction (AMR) after high-dose-rate interstitial brachytherapy at 54 Gy/9 fractions (HDR54) as monotherapy administered twice a day for tongue cancer in 13 patients, and attempted to validate HDR54 by comparing the AMR with that of our previously reported HDR at 60 Gy/10 fractions (HDR60), and low-dose-rate interstitial brachytherapy at approximately 70 Gy (LDR70).

Methods: The European Organization for Research on Treatment of Cancer/ Radiation Therapy Oncology Group scoring system with modifications (score: 1-4.5) was used to evaluate AMR.

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In CT-guided percutaneous punctures-an image-guided puncture method using CT images-physicians treat targets such as lung tumors, liver tumors, renal tumors, and intervertebral abscesses by inserting a puncture needle into the body from the exterior while viewing images. By recognizing two-dimensional CT images prior to a procedure, a physician determines the least invasive puncture route for the patient. Therefore, the candidate puncture route is limited to a two-dimensional region along the cross section of the human body.

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Background/aim: Endoscopic submucosal dissection (ESD) followed by chemoradiotherapy (CRT) has become a promising treatment modality in the management of early-stage superficial esophageal squamous cell carcinoma (SESCC). However, radiotherapy often leads to significant adverse events (AEs), including cardiopulmonary toxicity, limiting the delivery of this treatment modality. This study aimed to evaluate the efficacy of reduced-volume radiotherapy and dose-dense chemotherapy in mitigating AEs for high-risk SESCC following ESD.

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Background This study was aimed at analyzing the impact of postoperative radiotherapy (PORT) after breast-conserving surgery (BCS) on Japanese patients with early-stage breast cancer and exploring the potential of PORT omission. Materials and methods Data from 794 patients with early-stage breast cancer (T1-2, N0-1), who underwent BCS with (n = 310) or without PORT (n = 484) were retrospectively analyzed. Local control (LC) rate and breast cancer-specific survival (BCSS) were compared between the groups that received and did not receive PORT in the whole cohort and low-risk cohort (i.

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Article Synopsis
  • The study investigates the use of high-dose-rate (HDR) brachytherapy for treating recurrent gynecologic cancer in Japan, analyzing patient data from multiple centers to assess its clinical effectiveness.
  • A total of 165 patients were treated from 2000 to 2018, with outcomes showing varied survival and control rates depending on the type of cancer and timing of reirradiation.
  • The findings suggest that HDR brachytherapy can be effective for recurrent cases, particularly when there's a longer gap before reirradiation, but also highlight a significant rate of severe complications in some patients.
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We aimed to retrospectively review outcomes in patients with high-risk prostate cancer and a Gleason score ≤ 6 following modern radiotherapy. We analyzed the outcomes of 1374 patients who had undergone modern radiotherapy, comprising a high-risk low grade [HRLG] group (Gleason score ≤ 6; n = 94) and a high-risk high grade [HRHG] group (Gleason score ≥ 7, n = 1125). We included 955 patients who received brachytherapy with or without external beam radio-therapy (EBRT) and 264 who received modern EBRT (intensity-modulated radiotherapy [IMRT] or stereotactic body radiotherapy [SBRT]).

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  • The study evaluated the effectiveness of hands-on training (HoT) and surveys on 3D image-guided brachytherapy (3D-IGBT) and hybrid brachytherapy (HBT) for cervical cancer among 29 healthcare professionals in Japan.
  • Participants completed questionnaires before and after the training, revealing key concerns like applicator insertion, human resource shortages, and pain management; feedback led to adjustments in the HoT content.
  • Post-training, a significant reduction in anxiety was noted across all professions, with an average satisfaction score of 9.52 out of 10, indicating that the tailored HoT was successful in addressing participants' concerns.
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Objective: We developed fiducial imaging-guidance markers for the prostate with less imaging artifacts than currently commercially available markers. The aim of this study was to evaluate the imaging artifacts and potential usefulness and safety of these novel fiducial imaging markers in preclinical experiments.

Methods: We selected specific metal materials and a shape that can minimize artifacts in line with a license we obtained for a metal with a gold-platinum (Au-Pt) alloy composition that maximized artifact-free MRI images.

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Article Synopsis
  • A nationwide survey in Japan assessed brachytherapy (BT) resources, practices, and resident education across 177 establishments, achieving a high response rate of 90%.
  • The survey revealed that while most prefectures offer BT for gynecological and prostate cancers, there's limited access to interstitial BT for other cancer types, with significant variability in patient caseloads.
  • Only 47% of BT training centers felt they could provide adequate resident training, citing insufficient patient numbers as a major obstacle, indicating a need for improved access and training in advanced BT techniques.
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To examine the impact of ultra-high iPSA levels of >50 ng/mL (uhPSA) after modern radiotherapy, we compared outcomes of 214 patients with uhPSA levels to 1161 other high-risk patients. Radiotherapy included brachytherapy ± external beam radiotherapy (EBRT) and EBRT alone (intensity-modulated radiotherapy or stereotactic body radiotherapy). The biochemical disease-free survival rate (bDFS), the distant metastasis-free survival rate (DMFS), local control, and pelvic lymph node control were analyzed.

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Background To analyze the feasibility of omitting postoperative radiotherapy (PORT) after breast-conserving surgery (BCS) in Japanese patients with ductal carcinoma in situ (DCIS). Materials and methods We retrospectively analyzed 88 patients with small pure DCIS (median diameter 1.1 cm, ≤ 4 cm) who underwent BCS with (n = 39) or without (n = 49) PORT.

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  • A study evaluated treatment outcomes based on prostate volumes (PVs) in prostate cancer patients who underwent various therapies, using data from a large Japanese cohort (J-POPS).
  • The analysis included 6,652 patients categorized into three groups by PV: <15 cc, 15-20 cc, and >20 cc, assessing factors like biochemical freedom from failure (bFFF) and mortality rates over a median follow-up of 60 months.
  • The findings showed no significant differences in bFFF, prostate cancer-specific mortality, or all-cause mortality across PV groups, indicating that permanent seed implantation remains effective even for smaller prostate sizes.
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Purpose: Advances in three-dimensional image-guided brachytherapy technique allow for using intra-cavitary and interstitial brachytherapy (ICIS-BT), and sole interstitial brachytherapy (ISBT) in addition to conventional intra-cavitary brachytherapy (ICBT). However, no consensus has been reached regarding the choice of these techniques. The aim of this study was to propose the size criteria for indication of interstitial techniques.

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Purpose: We investigated the long-term oncological outcome of high-dose-rate (HDR) multicatheter interstitial brachytherapy (MIB) for adjuvant accelerated partial breast irradiation (APBI) after breast conserving surgery in Japanese patients.

Material And Methods: Between June 2002 and October 2011, 86 breast cancer patients were treated at National Hospital Organization Osaka National Hospital (trial number of the local institutional review board, 0329). Median age was 48 years (range, 26-73 years).

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Objective: Compared with the implementation speed of image-guided adaptive brachytherapy for uterine cervical cancer, that of intracavitary and interstitial brachytherapy is slow, possible because it requires more invasive procedure of inserting needles directly into tumours. To accelerate the implementation speed of intracavitary and interstitial brachytherapy, a first hands-on seminar for image-guided adaptive brachytherapy and intracavitary and interstitial brachytherapy for uterine cervical cancer was held on 26 November 2022, supported by Japanese Society for Radiology and Oncology. This article deals with this hands-on seminar and difference of degree of confidence of participants in starting intracavitary and interstitial brachytherapy before and after the seminar.

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Purpose: We evaluated the effect of age, <60 and ≥60 years, on biochemical outcomes and toxicities in patients with prostate cancer who underwent permanent seed implantation (PI) ± external beam radiation therapy ± hormone therapy in a national Japanese prospective cohort study (J-POPS).

Methods And Materials: The safety and efficacy analyses included 6721 and 6662 patients, respectively. We categorized patients into two age groups: <60 (n = 716) and ≥60 (n = 6,005) years.

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Article Synopsis
  • Esophagectomy is typically the go-to treatment for superficial esophageal squamous cell carcinoma (SESCC) after noncurative endoscopic submucosal dissection (ESD), but recent studies suggest that chemoradiotherapy (CRT) may also be effective.
  • This study compared the long-term outcomes of 60 SESCC patients who received either CRT or esophagectomy following noncurative ESD, finding that overall and disease-free survival rates were similar between the two treatment groups.
  • Results indicated that CRT could be a promising non-surgical alternative for treating high-risk SESCC patients, suggesting the need for more research in this area.
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Background/aim: The purpose of this study was to retrospectively review the outcomes of intramedullary spinal cord metastasis (ISCM) and identify predictors for ambulation after radiotherapy (RT).

Patients And Methods: We analyzed 16 lesions in 15 patients treated with RT for ISCM at our clinic from October 2009 to April 2020 to evaluate predictors for improved ambulation following RT.

Results: The primary diseases included nine cases of lung cancer, two cases of breast cancer, and several others.

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Currently, tongue cancers are primarily managed by surgery, and interstitial brachytherapy is only recommended for a selected group of early state T1-2N0 patients who refuse surgery or are medically inoperable. In this report, a case with T3N2cM0 tongue cancer who has been effectively treated by the combination of concurrent chemoradiotherapy involving volumetric arc therapy and boost high-dose rate interstitial brachytherapy is presented. Of course, surgery remains the main treatment strategy for tongue cancer patients; however, the authors believe that if volumetric arc therapy is carefully planned to reduce the mandible dose as much as possible and high-dose rate interstitial brachytherapy with a mouthpiece that protects the mandible is combined, it is possible to treat T3N2 disease, and this can be considered for patients who want to preserve organ function.

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Elective nodal irradiation (ENI) and involved field radiotherapy (IFRT) are definitive radiotherapeutic approaches used to treat patients with limited-disease small cell lung cancer (LD-SCLC). However, no solid consensus exists on their optimal target volume. The current study aimed to assess the clinical outcomes of patients with LD-SCLC who received definitive ENI or IFRT.

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This study examined the role of brachytherapy boost (BT-boost) and external beam radiotherapy (EBRT) in intermediate- to high-risk prostate cancer, especially in patients with very high-risk factors (VHR: T3b-4 or Gleason score 9-10) as patients with double very high-risk factors (VHR-2: T3b-4 and Gleason score 9-10) previously showed worst prognosis in localized prostate cancer. We retrospectively reviewed multi-institutional data of 1961 patients that were administered radiotherapy (1091 BT-boost and 872 EBRT: 593 conventional-dose RT (Conv RT: equivalent to doses of 2 Gy per fraction = EQD2 ≤ 72 Gy) and 216 dose-escalating RT (DeRT = EQD2 ≥ 74 Gy). We found that BT-boost improved PSA control and provided an equivalent overall survival rate in the intermediate- and high-risk groups, except for patients within the VHR factor group.

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It has been postulated that the combination of intracavitary and interstitial brachytherapy (IC/IS) is effective and safe for large and irregularly shaped uterine cervical cancer patients. However, due to its invasiveness compared to conventional intracavitary brachytherapy (ICBT), it has to be said that the implementation speed of IC/IS is slow. Until now, there have been no guidelines for required equipment, human resources, and procedural guide focusing solely on IC/IS.

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To compare gastrointestinal (GI) and genitourinary (GU) toxicities in patients with localized prostate cancer treated with ultrahypofractionated radiotherapy (UHF) or brachytherapy [BT; low dose rate, LDR or high dose rate (HDR) with or without external beam radiotherapy (EBRT)]. We compared 253 UHF and 1664 BT ± EBRT groups. The main outcomes were the incidence and severity of acute and late GU and GI toxicities.

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Aim: This study presents multi-institutional individual data of reirradiation (ReRT) for head and neck cancer using brachytherapy (ReRT-BT) collected by national surveillance in Japan.

Methods And Materials: We distributed an e-mail-based questionnaire to 153 institutions equipped with high-dose-rate (HDR) brachytherapy facilities and received responses from 76 institutions (49.7%).

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