Shiraishi, Yutaka



School of Medicine, Department of Radiology (Radiation Oncology) (Shinanomachi)


Assistant Professor/Senior Assistant Professor

Career 【 Display / hide

  • 2004.05

    国立病院機構東京医療センター, 初期臨床研修医

  • 2006.05

    慶應義塾大学医学部, 放射線科学, 専修医

  • 2008.04

    国立病院機構東京医療センター, 放射線科, レジデント

  • 2009.10

    国立病院機構東京医療センター, 放射線科, 医員

  • 2011.04

    慶應義塾大学医学部, 放射線治療科, 助教

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Academic Background 【 Display / hide

  • 1998.04

    慶應義塾大学, 医学部

    University, Graduated

Academic Degrees 【 Display / hide

  • 博士(医学), 慶應義塾大学, Dissertation, 2013.12


Papers 【 Display / hide

  • Effect of adding androgen deprivation therapy to permanent iodine-125 implantation with or without external beam radiation therapy on the outcomes in patients with intermediate-risk prostate cancer: A propensity score–matched analysis

    Sutani S., Yorozu A., Toya K., Shiraishi Y., Nishiyama T., Yagi Y., Nakamura K., Saito S.

    Brachytherapy (Brachytherapy)  20 ( 1 ) 10 - 18 2021.01

    ISSN  15384721

     View Summary

    Purpose: The purpose of the study was to evaluate the effect of adding androgen deprivation therapy (ADT) to brachytherapy with or without external beam radiation therapy on oncological outcomes in prostate cancer. Methods and Materials: Overall, 1,171 patients with intermediate-risk prostate cancer treated with brachytherapy with or without external beam radiation therapy with or without ADT between 2003 and 2013 were identified. Propensity score matching was used to counter biases between the ADT and non-ADT groups. The biochemical failure-free rate (bFFR), local recurrence-free rate, and overall survival rate were evaluated using Kaplan–Meier curves, and predictors were identified using Cox proportional hazards regression models. Results: After propensity score matching, 405 patients were included in each group. The median followup duration was 9.1 years; the median ADT duration was 6 months. In the ADT versus non-ADT groups, the 9-year bFFR, local recurrence-free rate, and overall survival rate were 93.4% versus 87.8% (p = 0.016), 96.9% versus 98.1% (p = 0.481), and 88.1% versus 90.4% (p = 0.969), respectively. On multivariate analyses, Gleason score (hazard ratio [HR]: 2.52, 95% confidence interval [CI]: 1.58–4.03) and ADT use (HR: 0.55, 95% CI: 0.34–0.89) were associated with biochemical failure. Supplemental external beam radiation therapy use (HR: 0.38, 95% CI: 0.16–0.91) was associated with lower local recurrence rates. Age (HR: 1.12, 95% CI: 1.08–1.16) and comorbidities (HR: 1.56, 95% CI: 1.04–2.34) were associated with all-cause mortality. Conclusions: A risk-benefit assessment between bFFR improvement and the potential side effects of adding ADT to brachytherapy-based radiotherapy is warranted before incorporating ADT as routine practice.

  • Time to achieve a prostate-specific antigen nadir of ≤0.2 ng/mL and related factors after permanent prostate brachytherapy

    Soyano T., Yorozu A., Natsume N., Hanada T., Shiraishi Y., Toya K., Saito S.

    Brachytherapy (Brachytherapy)  20 ( 1 ) 29 - 37 2021.01

    ISSN  15384721

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    Purpose: The purpose of this study was to identify the time to achieve a prostate-specific antigen (PSA) nadir of ≤0.2 ng/mL and the related factors to achieve this goal. Materials and Methods: We retrospectively reviewed 2218 Japanese prostate cancer patients who received 125I brachytherapy with or without external beam radiotherapy between 2003 and 2013 at one institution. Among them, patients followed up for ≥72 months and without luteinizing hormone–releasing hormone (LH-RH) agonist/antagonist were included (total of 1089 patients). The time to a PSA nadir of ≤0.2 ng/mL (months) was defined as the time between the date of implantation and the first time the lowest PSA value reached ≤0.2 ng/mL. Biochemical recurrence (BCR) was determined using the Phoenix definition. Multivariate linear regression analysis was performed to detect the related factors to achieve this nadir. Results: We assigned 409, 592, and 88 patients to the low-, intermediate-risk, and high-risk groups, respectively. The median followup time was 9.5 years. The median time to achieve a PSA nadir of ≤0.2 ng/mL was 44.0 (95% confidence interval: 42.3–45.7) months. The percentage of patients that achieved the nadir was 89.1%. BCR was noted in 107 (9.8%) patients. In the multivariate analysis of patients without BCR, younger age, larger prostate volume at implantation, higher initial PSA level, and monotherapy were significantly associated with longer time to achieve the PSA nadir. Conclusion: The median time to achieve a PSA nadir of ≤0.2 ng/mL was 44.0 months. Some patients, however, may require a lengthy period of time to do so.

  • Prediction of Severe Lymphopenia During Chemoradiation Therapy for Esophageal Cancer: Development and Validation of a Pretreatment Nomogram

    van Rossum P.S.N., Deng W., Routman D.M., Liu A.Y., Xu C., Shiraishi Y., Peters M., Merrell K.W., Hallemeier C.L., Mohan R., Lin S.H.

    Practical Radiation Oncology (Practical Radiation Oncology)  10 ( 1 ) e16 - e26 2020.01

    ISSN  18798500

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    Introduction: In patients with esophageal cancer, occurrence of severe radiation-induced lymphopenia during chemoradiation therapy has been associated with worse progression-free and overall survival. The aim of this study was to develop and validate a pretreatment clinical nomogram for the prediction of grade 4 lymphopenia. Methods and Materials: A development set of consecutive patients who underwent chemoradiation therapy for esophageal cancer and an independent validation set of patients from another institution were identified. Grade 4 lymphopenia was defined as an absolute lymphocyte count nadir during chemoradiation therapy of <0.2 × 103/μL. Multivariable logistic regression analysis was used to create a prediction model for grade 4 lymphopenia in the development set, which was internally validated using bootstrapping and externally validated by applying the model to the validation set. The model was presented as a nomogram yielding 4 risk groups. Results: Among 860 included patients, 322 (37%) experienced grade 4 lymphopenia. Higher age, larger planning target volume in interaction with lower body mass index, photon- rather than proton-based therapy, and lower baseline absolute lymphocyte count were predictive in the final model (corrected c-statistic, 0.76). External validation in 144 patients, among whom 58 (40%) had grade 4 lymphopenia, yielded a c-statistic of 0.71. Four nomogram-based risk groups yielded predicted risk rates of 10%, 24%, 43%, and 70%, respectively. Conclusions: A pretreatment clinical nomogram was developed and validated for the prediction of grade 4 radiation-induced lymphopenia during chemoradiation therapy for esophageal cancer. The nomogram can risk stratify individual patients suitable for lymphopenia-mitigating strategies or potential future therapeutic approaches to ultimately improve survival.

  • A multidisciplinary approach to soft-tissue sarcoma of the extremities

    Nakayama R., Mori T., Okita Y., Shiraishi Y., Endo M.

    Expert Review of Anticancer Therapy (Expert Review of Anticancer Therapy)   2020

    ISSN  14737140

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    Introduction: Soft-tissue sarcoma (STS) denotes a group of rare and highly heterogeneous malignant tumors of mesenchymal origin. Accurate histological diagnosis is critical for selecting appropriate treatment. Complete tumor resection is the primary treatment for STS, and the efficacies of radiotherapy and chemotherapy have been tested in the adjuvant setting to improve oncological outcomes. Because most STS lesions arise in the extremities, preserving limb function and managing limb impairment after radical local treatment represent significant challenges. Areas covered: This article reviews the current front-line treatments for patients with extremity STS and discusses the multidisciplinary team-based efforts needed to improve oncological outcomes and survivorship. Expert opinion: Given the rarity, variety, and complexity of STS, a multidisciplinary approach involving experts in various disciplines is vital for improving outcomes in patients ranging from diagnosis to survivorship. A major challenge is building a sustainable system in each region permitting all patients with extremity STS to be treated at high-volume centers with multidisciplinary teams dedicated to this rare and complex disease.

  • Severe lymphopenia during neoadjuvant chemoradiation for esophageal cancer: A propensity matched analysis of the relative risk of proton versus photon-based radiation therapy

    Shiraishi Y., Fang P., Xu C., Song J., Krishnan S., Koay E., Mehran R., Hofstetter W., Blum-Murphy M., Ajani J., Komaki R., Minsky B., Mohan R., Hsu C., Hobbs B., Lin S.

    Radiotherapy and Oncology (Radiotherapy and Oncology)  128 ( 1 ) 154 - 160 2018.07

    ISSN  01678140

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    © 2017 Elsevier B.V. Background and purpose: Circulating lymphocytes are exquisitely sensitive to radiation exposure, even to low scattered doses which can vary drastically between radiation modalities. We compared the relative risk of radiation-induced lymphopenia between intensity modulated radiation therapy (IMRT) or proton beam therapy (PBT) in esophageal cancer (EC) patients undergoing neoadjuvant chemoradiation therapy (nCRT). Material and methods: EC patients treated with IMRT and PBT were propensity matched based on key clinical variables. Treatment-associated lymphopenia was graded using CTCAE v.4.0. Using matched cohorts, univariate and multivariable multiple logistic regression was used to identify factors associated with increased risk of grade 4 lymphopenia as well as characterize their relative contributions. Results: Among the 480 patients treated with nCRT, 136 IMRT patients were propensity score matched with 136 PBT patients. In the matched groups, a greater proportion of the IMRT patients (55/136, 40.4%) developed grade 4 lymphopenia during nCRT compared with the PBT patients (24/136, 17.6%, P < 0.0001). On multivariable analysis, PBT was significantly associated with a reduction in grade 4 lymphopenia risk (odds ratio, 0.29; 95% confidence interval, 0.16–0.52; P < 0.0001). Conclusion: PBT is associated with significant risk reduction in grade 4 lymphopenia during nCRT in esophageal cancer.

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Papers, etc., Registered in KOARA 【 Display / hide

Reviews, Commentaries, etc. 【 Display / hide

Presentations 【 Display / hide

  • 外照射併用療法を考える―小線源療法適応拡大に向けてのステップ― 外照射併用療法の治療計画と実際「GIを中心とした注意事項について」

    Shiraishi Yutaka

    第十二回前立腺癌密封小線源永久挿入治療研究会, 2016, Symposium, Workshop, Panelist (nomination)

  • 外部放射線併用療法総論

    Shiraishi Yutaka

    第17回ヨウ素125シード線源永久挿入による前立腺癌密封小線源療法技術講習会 (東京) , 2015, Public discourse, seminar, tutorial, course, lecture and others

  • Normal Tissue Complication Probability (NTCP) Modeling of Late Rectal Bleeding Following Iodine-125 Prostate Brachytherapy Combined With External Beam Radiation Therapy.

    Shiraishi Yutaka

    The 57th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (San Antonio) , 2015, Poster (general)

  • Transperineal Mapping Biopsy Results following Continuous PSA Rises in Patients Treated with Iodine-125 Prostate Brachytherapy

    Shiraishi Yutaka

    15th International Congress of Radiation Research (Kyoto) , 2015, Poster (general)

  • Brachytherapy with or without External Beam Radiotherapy. Outcomes and Toxicities at Tokyo Medical Center.

    Shiraishi Yutaka

    Dr. Grimm Online Workshop (Tokyo) , 2015, Public discourse, seminar, tutorial, course, lecture and others

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Research Projects of Competitive Funds, etc. 【 Display / hide

  • ニューラルネットワークを用いた前立腺癌小線源治療の予後予測モデルの構築


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 白石 悠, Grant-in-Aid for Scientific Research (C), Principal Investigator

     View Summary

    直腸出血を予測するモデルを構築した経験を活かし、小線源治療後の他の有害事象や、生化学的再発あるいは臨床的再発部位を予測するモデルを構築していく。再発時の病理結果をモデルに組み込むことで、生化学的再発だけでなく、病理学的再発や、再発と紛らわしいPSA bounceの予測モデル構築にもチャレンジできると考えている。訓練データ・テストデータの量が大きくなり計算に時間がかかることも予想される。その場合には適宜新たなコンピュータの導入を検討していく。


Courses Taught 【 Display / hide







Courses Previously Taught 【 Display / hide

  • 系統講義

    Keio University, 2015

  • 臨床実習

    Keio University, 2015, Full academic year, Major subject, Laboratory work/practical work/exercise