Ozawa, Hiroyuki



School of Medicine, Department of Otorhinolaryngology, Head and Neck Surgery (Shinanomachi)



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Academic Degrees 【 Display / hide

  • 博士(医学), Keio University, 2010.01

Licenses and Qualifications 【 Display / hide

  • 耳鼻咽喉科専門医, 2003.09

  • 日本癌治療医認定医機構 癌治療認定医, 2008.04

  • 日本頭頸部外科学会 頭頸部がん専門医, 2010.10


Research Areas 【 Display / hide

  • Tumor therapeutics

  • Otorhinolaryngology

Research Keywords 【 Display / hide

  • Thyroid tumor

  • Skull Base Tumor

  • Head and Neck Cancer

  • Carotid Body Tumor

Research Themes 【 Display / hide

  • Genetic factor and tumor progression mechanism of carotid body tumor, 


  • Head and Neck Cancer metastasis, 



Papers 【 Display / hide

  • Cyclooxygenase‑2 expression is associated with chemoresistance through cancer stemness property in hypopharyngeal carcinoma

    Saito S., Ozawa H., Imanishi Y., Sekimizu M., Watanabe Y., Fumihiro I.T.O., Ikari Y., Nakahara N., Kameyama K., Ogawa K.

    Oncology Letters (Oncology Letters)  22 ( 1 )  2021.07

    ISSN  17921074

     View Summary

    Cyclooxygenase‑2 (COX‑2) is one of the two isoforms of COX, an enzyme that catalyzes the conversion of arachidonic acid to prostaglandins. COX‑2 is associated with the progression in various types of cancer, and its expres‑ sion has been associated with a poor prognosis in head and neck squamous cell carcinoma (HNSCC). Furthermore, COX‑2 expression has been associated with resistance to anticancer drugs. However, the precise mechanism of COX‑2 for chemoresistance in HNSCC has not been fully elucidated. The present study aimed to investigate the effect of COX‑2 on cancer stem cell (CSC) property and to reveal its effect on chemoresistance using in vitro and clinicopathological assays in HNSCC cells and tissues. The current study analyzed the immunohistochemical expression levels of COX‑2 and clinicopathological factors using matched samples of pretreatment biopsy and surgical specimens from patients with hypopharyngeal carcinoma who underwent tumor resec‑ tion with preoperative chemotherapy, including docetaxel. Additionally, the chemoresistance to docetaxel with or without a COX‑2 inhibitor (celecoxib) was examined in HNSCC cell lines by MTS assays. To evaluate the association of COX‑2 expression with stemness property, the expression levels of CSC‑associated genes after exposure to celecoxib were assessed by reverse transcription‑quantitative PCR. A sphere formation assay was also performed using ultra‑low attachment dishes and microscopic imaging. The immunohistochemical analysis of biopsy specimens revealed a negative association between COX‑2 expression in biopsy specimens and the pathological effect of induction chemotherapy in surgical specimens. The cell survival rate under exposure to docetaxel was decreased by the addition of celecoxib. COX‑2 inhibition led to downregulation of CSC‑associated gene expression and sphere formation. The present findings suggested that COX‑2 expression may be associated with chemoresistance through the cancer stemness property, and inhibition of COX‑2 may enhance chemo‑sensitivity in HNSCC. Therefore, COX‑2 may be an attractive target for the treatment of HNSCC.

  • Prognostic Value of the Lymphocyte-to-Monocyte Ratio in Patients with Parotid Gland Carcinoma

    Mikoshiba T., Ozawa H., Watanabe Y., Sekimizu M., Saito S., Yoshihama K., Nakamura S., Imanishi Y., Kameyama K., Ogawa K.

    Laryngoscope (Laryngoscope)  131 ( 3 ) E864 - E869 2021.03

    ISSN  0023852X

     View Summary

    Objective: Previous studies have evaluated various markers as prognostic predictors in patients with many types of cancers. However, the influence of such factors on the outcomes of patients with parotid gland carcinoma (PGC) is unknown. This study investigated the roles of alternative markers in the prognoses of patients with PGC. Methods: Overall, 101 patients who underwent curative treatment for PGC were retrospectively evaluated, and their 5-year overall and disease-free survival rates were calculated. The prognostic values of clinical and pathologic factors were determined. Results: The 5-year overall and disease-free survival rates were 73.1% and 62.8%, respectively. Multivariate analysis revealed that a low lymphocyte-to-monocyte ratio (LMR), high T classification, high N classification, and perineural invasion were independent predictors of poor prognosis. Conclusions: Thus, we identified LMR as an independent prognostic factor for patients with PGC. Patients with low LMRs who are amenable to treatment may require adjuvant treatment to improve their prognoses. Level of Evidence: 4 Laryngoscope, 131:E864–E869, 2021.

  • Transoral Removal of Tumors of the Dorsal Aspect of the Soft Palate: A Technical Note

    Nakamura S., Ozawa H., Sekimizu M., Ikari Y., Nakahara N., Saito S., Yoshihama K., Nishiyama Y., Ogawa K.

    Laryngoscope (Laryngoscope)   2021

    ISSN  0023852X

  • The clinicopathological significance of the adipophilin and fatty acid synthase expression in salivary duct carcinoma

    Hirai H., Tada Y., Nakaguro M., Kawakita D., Sato Y., Shimura T., Tsukahara K., Kano S., Ozawa H., Okami K., Sato Y., Fushimi C., Shimizu A., Okamoto I., Takase S., Okada T., Sato H., Imanishi Y., Otsuka K., Watanabe Y., Sakai A., Ebisumoto K., Togashi T., Ueki Y., Ota H., Saigusa N., Takahashi H., Ando M., Urano M., Hanazawa T., Nagao T.

    Virchows Archiv (Virchows Archiv)  477 ( 2 ) 291 - 299 2020.08

    ISSN  09456317

     View Summary

    Salivary duct carcinoma (SDC) is an aggressive, uncommon tumor histologically comparable to high-grade mammary ductal carcinoma. SDCs are usually androgen receptor (AR)–positive and often HER2-positive. Recently, therapies targeting these molecules for SDC have attracted attention. Lipid metabolism changes have been described in association with biological behavior in various cancers, although no such relationship has yet been reported for SDC. We therefore analyzed the clinicopathological relevance of the immunohistochemical expression of adipophilin (ADP) and fatty acid synthase (FASN), representative lipid metabolism–related proteins, in 147 SDCs. ADP and FASN were variably immunoreactive in most SDCs (both 99.3%), and the ADP and FASN expression was negatively correlated (P = 0.014). ADP-positive (≥ 5%) SDCs more frequently exhibited a prominent nuclear pleomorphism and high-Ki-67 labeling index than those ADP-negative (P = 0.013 and 0.011, respectively). In contrast, a high FASN score, calculated by the staining proportion and intensity, (≥ 120) was correlated with the high expression of AR and FOXA1 (P < 0.001 and = 0.003, respectively). The ADP and FASN expression differed significantly among the subtypes based on biomarker immunoprofiling, as assessed by the AR, HER2, and Ki-67 status (P = 0.017 and 0.003, respectively). A multivariate analysis showed that ADP-positive expression was associated with a shorter overall and progression-free survival (P = 0.018 and 0.003, respectively). ADP was associated with an aggressive histopathology and unfavorable prognosis, and FASN may biologically interact with the AR signaling pathway in SDC. ADP may, therefore, be a new prognostic indicator and therapeutic target in SDC.

  • Endoscopic endonasal removal of a pediatric paranasal ossifying fibroma using preoperative embolization

    Saito S., Ozawa H., Ikari Y., Nakahara N., Ito F., Sekimizu M., Kameyama K., Akiyama T., Toda M., Ogawa K.

    Otolaryngology Case Reports (Otolaryngology Case Reports)  14 2020.03

     View Summary

    Background: Ossifying fibroma arising in the sinonasal tract is rare. Its treatment includes complete resection; however, this can be challenging to perform due to the well-vascularized nature of the fibroma. Some surgical techniques can control intraoperative hemorrhage; however, to date, no reports have assessed the use of preoperative embolization. Methods: We report a case of a child with ossifying fibroma arising from the ethmoid sinus, which was resected by endoscopic surgery using preoperative transarterial embolization. Conclusions: Embolization was effective in decreasing intraoperative hemorrhage. No complications related to the procedure or operation were encountered. Preoperative embolization should be considered for better control of the bleeding that occurs in ossifying fibromas, similar to that in other well-vascularized tumors.

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

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

  • 頭頸部癌における低酸素応答因子の免疫応答への影響の解析とその臨床応用


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 小澤 宏之, Grant-in-Aid for Scientific Research (C), Principal Investigator

  • Development of head and neck cancer treatment targeting HIF1-alpha


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 小澤 宏之, Grant-in-Aid for Scientific Research (C), Principal Investigator

  • Analysis of HIF1-alpa expression for head and neck cancer metastasis


    MEXT,JSPS, Grant-in-Aid for Scientific Research, 小澤 宏之, Grant-in-Aid for Scientific Research (C), Principal Investigator

     View Summary

    The aim of the present study was to investigate the molecular targets of HIF1-α relevant to metastasis, and to find out an impact of HIF1-α to HNSCC metastasis by clinicopathological assays. In immunohistochemical study, the HIF-1α expression was higher in cancer cells than in normal cells of the adjacent normal mucosa. Univariate analysis revealed that high expression of HIF-1α was significantly correlated with T-classification (P=0.012), lymph node metastasis (P=0.002) and lymphatic invasion (P=0.03). HIF-1 inhibitor downregulated the expression of HIF-1α, twist, Oct3/4 and Nanog of head and neck cancer cells.
    These results suggest that HIF-1α plays a key role for the tumor progression of HNSCC through EMT and CSC property. From the present study, HIF-1α inhibition may have the possibility to suppress tumor metastasis, thus HIF-1α is attractive target for the treatment of HNSCC.


Courses Taught 【 Display / hide











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Courses Previously Taught 【 Display / hide

  • Skull base tumors

    Keio University, 2017

  • Head and Neck cancer

    Keio University, 2017, Major subject


Memberships in Academic Societies 【 Display / hide

  • The Oto-Rhino-Laryngological Society of Japan

  • Japan Society for Head and Neck Cancer

  • Japan Society for Head and Neck Surgery

  • Japanese Society for Skull Base Surgery

  • The Society of Practical Otolaryngology


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