Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Masao Asai is active.

Publication


Featured researches published by Masao Asai.


Cancer | 1998

Tumor thickness predicts cervical metastasis in patients with stage I/II carcinoma of the tongue†

Takahiro Asakage; Tomoyuki Yokose; Kiyoshi Mukai; Shoichiro Tsugane; Yoshitaka Tsubono; Masao Asai; Satoshi Ebihara

The incidence of cervical metastases after surgery for Stages I/II carcinoma of the tongue is 30‐40%. Postoperative cervical metastases are an adverse prognostic factor for patients with this malignancy. The purpose of this study was to evaluate the clinicopathologic factors associated with late cervical metastases in patients with carcinoma of the tongue.


Plastic and Reconstructive Surgery | 1999

Comparison of innervated and noninnervated free flaps in oral reconstruction.

Yoshihiro Kimata; Kiyotaka Uchiyama; Satoshi Ebihara; Seiji Kishimoto; Masao Asai; Masahisa Saikawa; Waichiro Ohyama; Tastumasa Haneda; Ryuichi Hayashi; Tetsuro Onitsuka; Takashi Nakatsuka; Kiyonori Harii

Thirteen patients who had undergone ablative surgery for advanced squamous cell carcinoma in which more than half of the tongue had been resected underwent reconstruction in which the cutaneous nerve of a free flap was anastomosed to the stump of the transected lingual nerve. Eight of the patients underwent reconstruction with an innervated anterolateral thigh flap and five patients underwent reconstruction with an innervated rectus abdominis musculocutaneous flap. Sensory recovery of the flap at least 6 months postoperatively was compared in these 13 patients and in 16 additional patients who received noninnervated versions of the same flaps for the same defect. The degree of sensory recovery of innervated thigh flaps was significantly greater than that of noninnervated ones in all modalities and that of innervated rectus abdominis flaps was also greater than that of noninnervated flaps, except for hot and cold perception. These results indicate that sensory regrowth occurs in most areas through the surgically created pathways. However, results of Semmes-Weinstein testing showed that recovery did not reach the level of protective sensation in either type of innervated flap. Although these findings must be followed by additional objective and functional tests and the need for sensory reeducation should be considered, this simple operative procedure can improve postoperative intraoral function and should be attempted whenever possible after ablative surgery.


Cancer | 2002

Results of Multimodality Therapy for Squamous Cell Carcinoma of Maxillary Sinus

Ken-ichi Nibu; Masashi Sugasawa; Masao Asai; Keiichi Ichimura; Masato Mochiki; Atsuro Terahara; Nobutaka Kawahara; Hirotaka Asato

A wide variety of modalities, including surgery, radiation therapy, and chemotherapy, alone or in combination, have been used for the treatment of squamous cell carcinoma (SCC) of the maxillary sinus to obtain better local control and maintain functions. However, there is still much controversy with regard to the optimum treatment.


Plastic and Reconstructive Surgery | 2000

Postoperative complications and functional results after total glossectomy with microvascular reconstruction

Yoshihiro Kimata; Kiyotaka Uchiyama; Satoshi Ebihara; Masahisa Saikawa; Ryuichi Hayashi; Tatsumasa Haneda; Waichiro Ohyma; Seiji Kishimoto; Masao Asai; Takashi Nakatsuka; Kiyonori Harii

Microsurgical reconstruction after total glossectomy can greatly improve quality of life; however, postoperative functional results are often unstable, and the effectiveness of total glossectomy remains questionable. To determine the problems of reconstruction after total glossectomy with laryngeal preservation and to examine the functional results of swallowing and speech, 30 patients who had undergone total glossectomy and reconstruction with free flaps were reviewed for this study. The patients ranged in age from 20 to 73 years, and 23 of the 30 had undergone reconstruction with a rectus abdominis musculocutaneous flap. Wider and thicker flaps were designed and transferred and were sutured to suspend the larynx. To maintain physiologic swallowing function after surgery, the extent of laryngeal suspension and cricopharyngeal myotomy was limited. Of the 30 patients, 21 (70 percent) could be decannulated with laryngeal preservation; 20 of these 21 could tolerate a normal/soft/pureed diet, and 1 was limited to a fluid diet. Speech was intelligible in 16 of the 19 patients evaluated. In 9 of the 30 patients, laryngeal function could not be preserved. In four of these nine patients, additional resection combined with total glossectomy caused severe aspiration and recurrent pneumonia. Two patients with preoperative cerebral dysfunction were also poor candidates for laryngeal preservation. Additionally, the transferred flap’s lack of bulk in the oral cavity and the advanced age (73 years) of one patient and the poor motivation of another may have contributed to postoperative aspiration. Aspiration occurred in one patient because of local recurrence of a tumor. The presence of preoperative cerebral dysfunction (p = 0.025), resection of the epiglottis (p = 0.005), and postoperative orocutaneous fistulas (p = 0.04) were significantly associated with the failure of laryngeal preservation. However, because of the difficulty of enrolling a sufficient number of patients in the study and the inherent limitations of retrospective studies, multivariate analysis in this study showed that no factors, such as patient age, flap volume, and the type of neck dissection, were significant predictors of laryngeal preservation. Although prospective studies are necessary, the function of individual patients must be assessed so that the study experiences discussed here can be applied to subsequent patients.


Modern Pathology | 2013

SOX10 is a novel marker of acinus and intercalated duct differentiation in salivary gland tumors: a clue to the histogenesis for tumor diagnosis.

Rie Ohtomo; Taisuke Mori; Shinsuke Shibata; Koji Tsuta; Akiko Miyagi Maeshima; Chihiro Akazawa; Yukio Watabe; Kazufumi Honda; Tesshi Yamada; Seiichi Yoshimoto; Masao Asai; Hideyuki Okano; Yae Kanai; Hitoshi Tsuda

Salivary gland tumors are relatively rare and morphologically diverse and heterogeneous tumors; therefore, histogenesis-based tumor markers are sorely needed to aid in diagnosing and determining the cell type of origin. SRY-related HMG-box 10 (SOX10) protein is a transcription factor known to be crucial in the specification of the neural crest and maintenance of Schwann cells and melanocytes. In addition, positive expression has also been implicated in the major salivary gland. Here, we examined SOX10 expression in various salivary gland tumors to correlate this expression with myoepithelial markers. Overall, 76 malignant and 14 benign tumors were examined. SOX10 expression clearly delineated two distinct subtypes of human salivary gland tumors; acinic cell carcinomas, adenoid cystic carcinomas, epithelial-myoepithelial carcinomas, myoepithelial carcinomas, and pleomorphic adenomas, including the pleomorphic adenoma component of carcinoma, were SOX10 positive, while salivary duct carcinomas, mucoepidermoid carcinomas, an oncocytic carcinoma, Oncocytomas, and Warthin tumors were SOX10 negative. Also, SOX10 was expressed in solid-type or non-specific morphology salivary gland tumors, but was not expressed in poorly differentiated squamous cell carcinomas. In normal human salivary gland tissue, SOX10 expression was specific to the nuclei of acini and both luminal and abluminal cells of intercalated ducts but not in other sites. Moreover, the murine model suggested that SOX10 continued to be expressed from the developmental stage to adulthood in the acinar and both luminal and abluminal intercalated ducts in the major salivary gland. Thus, SOX10 is a novel marker for diagnosing and understanding the histogenesis of salivary gland tumors.


Head and Neck-journal for The Sciences and Specialties of The Head and Neck | 1997

Preservation of the larynx after resection of a carcinoma of the posterior wall of the hypopharynx : Versatility of a free flap patch graft

Takashi Nakatsuka; Kiyonori Harii; Kazuki Ueda; Satoshi Ebihara; Masao Asai; Kouichi Hirano; Takashi Yoshizumi; Tadashi Sugasawa

Preservation of the larynx after resection of a pharyngeal tumor remains a challenging problem for the head and neck surgeon.


Radiotherapy and Oncology | 2011

Multicenter phase II study of an opioid-based pain control program for head and neck cancer patients receiving chemoradiotherapy

Sadamoto Zenda; Kazuto Matsuura; Hiroyuki Tachibana; Akihiro Homma; Tadaaki Kirita; Nobuya Monden; Shigemichi Iwae; Yojiro Ota; Tetsuo Akimoto; Hiroshi Otsuru; Makoto Tahara; Kengo Kato; Masao Asai

BACKGROUND The aim of this multi-center phase II study was to clarify the clinical benefit of an opioid-based pain control program for head and neck cancer patients during chemoradiotherapy. PATIENTS AND METHODS Head and neck cancer patients who were to receive definitive or postoperative chemoradiotherapy were enrolled. The opioid-based pain control program consisted of a three-step ladder, with basic regimens of: The primary endpoint of this study was compliance with radiotherapy. RESULTS A total of 101 patients from 10 institutions were registered between February 2008 and May 2009 and included in the analysis. The major combination chemotherapy regimen was cisplatin alone (76%). The rate of completion of radiotherapy was 99% and the rate of unplanned breaks in radiotherapy was 13% (13/101, 90% confidence interval: 9.9-16.5%). Median maximum quantity of morphine used per day was 35 mg (range 0-150 mg). CONCLUSIONS Use of a systematic pain control program may improve compliance with CRT.


Acta Oto-laryngologica | 2007

Clinicopathological factors related to cervical lymph node metastasis in a patient with carcinoma of the oral floor.

Mitsuya Suzuki; Tsunemiti Suzuki; Masao Asai; Keiichi Ichimura; Ken-ichi Nibu; Masashi Sugasawa; Kimitaka Kaga

Conclusion. Tumors developing into the muscle layer and tumor thickness ≥5 mm are the most important risk factors associated with nodal metastasis. Objective. It is necessary to identify the risk factors associated with cervical metastasis in patients with oral floor cancer to reveal the role of elective neck dissection for oral floor cancer. Patients and methods. Forty-eight patients with oral floor cancer were retrospectively analyzed for a correlation between clinicopathologic factors and cervical lymph node metastasis using Fishers exact test and a logistic regression test. Results. Univariate analysis showed significantly positive correlations for growth type, mitosis, perineural invasion, vascular invasion, lymphatic invasion, depth, thickness, and infiltration growth ratio. Multivariate analysis had a significantly positive correlation with nest formation and depth in all patients, and with thickness in patients with T1 or T2. In patients with bilateral cervical lymph node metastasis, lymph node metastasis was significantly positively correlated with perineural invasion.


Auris Nasus Larynx | 1994

Preoperative Embolization for Paraganglioma

Ryuzaburo Higo; Masao Asai; Masashi Sugasawa; Naonobu Takeuchi; Shigeru Nemoto

We have applied a new method of preoperative embolization to an intravagal and to carotid body paraganglioma, using estrogen dissolved in absolute alcohol and polyvinyl alcohol particles, which diffusely embolizes vessels from capillaries to main feeders. Total resection of the tumors after embolization was successively performed without postoperative complications; total blood loss was 205 and 130 ml, respectively, and the surgical time was approximately 3 hours in both cases. The technique, characteristics, and advantages of this method are discussed.


Microsurgery | 2011

Thoracoacromial vessels as recipients for head and neck reconstruction and cause of vascular complications

Satoshi Onoda; Minoru Sakuraba; Takayuki Asano; Shimpei Miyamoto; Ryuichi Hayashi; Masao Asai; Yoshihiro Kimata

Background: The choice of recipient vessels is an important factor for successful head and neck reconstruction. Finding good recipient vessels for neck microsurgery can be difficult after patients have undergone radiation therapy, previous neck dissection or developed neck infections due to pharyngocutaneous fistulae. Thoracoacromial arteries and veins can be good alternatives to common recipient vessels in such patients. We reviewed the complications, advantages and disadvantages associated with using thoracoacromial arteries and veins as recipient vessels. Methods: We reviewed eight patients whose thoracoacromial arteries and veins served as recipient vessels for head and neck reconstruction between 2002 and 2009. Preoperative status, reconstruction method and operative outcomes with complications were evaluated. Results: Postoperative complications related to microsurgical anastomosis developed in two of the eight patients. One arterial and venous thrombosis developed in each patient. We considered that the arterial thrombosis was derived from a technical problem with the operation and the venous thrombosis was derived from postoperative external pressure. Conclusions: Thoracoacromial arteries and veins are good recipient vessels for patients who have undergone ablative or reconstructive surgery, radiation therapy, or have a neck infection due to complications. However, we believe that using these vessels as recipients requires specific precautions that differ from those associated with general head and neck reconstruction.

Collaboration


Dive into the Masao Asai's collaboration.

Top Co-Authors

Avatar

Satoshi Ebihara

Osaka Electro-Communication University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Masashi Sugasawa

Saitama Medical University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Seiji Kishimoto

Tokyo Medical and Dental University

View shared research outputs
Top Co-Authors

Avatar
Top Co-Authors

Avatar

Minoru Sakuraba

Saitama Medical University

View shared research outputs
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge