There has been no attempt to clarify the status of carotid body tumor （CBT） patients in Japan. We analyzed CBT patients throughout Japan by gathering information on CBT patients from institutions that perform head and neck surgeries. Three-hundred ninety-nine patients were referred to 112 institutions during the past 20 years and 150 patients were registered in our study. There were 87 females and 63 males and their mean age was 48.0 years old. Eighteen patients had a family history of paragangliomas. Fifteen patients had bilateral CBTs. Out of these patients, informed consent was obtained from 61 cases and genetic variations were analyzed.
There were 25 cases （41.7％） without pathogenic genetic variants. Twenty-four cases （40.0％）, 9 cases （15.0％）, 1 case and 1 case had SDHD （succinate dehydrogenase complex subunit D）, SDHB （subunit B）, SDHC （subunit C） and VHL （von Hippel-Lindau） pathogenic variants, respectively. These results indicated the possibility that some gene alterations have penetrated into certain areas of Japan such as Miyagi, Iwate and Nagasaki. Further investigation is needed to clarify the gene alterations of CBT patients in these high-incidence areas and all over the country.

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Carotid body tumor （CBT） is a rare malignant tumor with a rich vascular network in and around it. When planning tumor resection, it is important to know the location of the tumor and its feeding arteries and to control the blood loss during the surgery. In our hospital, we perform preoperative embolization just before the resection surgery for all patients with CBT.
From March 2013 to December 2018, 15 consecutive patients were referred to our hospital with 16 CBTs that were resected after preoperative embolization. There were 9 female and 6 male patients with the mean age of 46 years. One patient had a tumor classified as Shamblin type I, and 15 had type Ⅱ tumors, including one patient who had bilateral CBTs. The mean operative time and the mean amount of blood loss were 138 min and 29.3 mL, respectively. The blood loss in our surgery was reduced greatly compared with other previous reports. There were no complications after preoperative embolization. We believe that adequate preoperative embolization followed by resection surgery leads to minimum blood loss and a safe surgery.
We explain our methods of preoperative embolization and surgery.

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In Japan, as of September 2020, two immune checkpoint inhibitors, nivolumab and pembrolizumab, have been approved for squamous cell carcinoma of the head and neck, and clinical evidence is being generated. Here, we review the two clinical trials （CheckMate 141 trial and KEYNOTE-048 trial） that were registration studies for marketing authorization, focusing on the differences between the two studies in the eligible patients, study design, concomitant drugs, and control drugs. In particular, both trials have different eligibility criteria for prior platinum treatment, which will also be explained.

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Reconstruction with microvascular free tissue transfer is useful for healing, appearance, and the preservation of function after head and neck cancer resection. Flap elevation, suturing, and vascular anastomosis are generally performed under microscopy by plastic surgeons. Since April 2017, however, this has been performed in our department by head and neck surgeons, except for the elevation of free jejunum. Here, we retrospectively evaluate this practice in 40 patients（41 flaps）undergoing treatment up to September 2019, focusing mainly on the perioperative period. There were 16 cases of primary tumors in the tongue and 12 cases in the hypopharynx, and almost all were advanced cancer. Pharyngolaryngoesophagectomy was performed in 13 cases, followed by subtotal tongue removal in 7 cases. Reconstruction materials consisted mainly of free jejunum in 12 cases and anterolateral thigh flap in 11 cases. Anastomosis with the pedicle was mainly done using the superior thyroid artery and internal jugular vein. Median operation time and blood loss were 603.5 minutes and 517.5ml, respectively. Intraoperative complications arose in 5 cases. Further, 17 cases had postoperative complications and reoperation was performed in 3 cases. No vascular thrombosis or leakage due to suture failure occurred. Although some points warrant improvement, performance was not significantly inferior to that in previous large studies.

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Adenoid cystic carcinoma （ACC） is a very rare epithelial tumor of the salivary glands. Surgical resection is considered to be a standard therapy. However, the optimal treatment strategy for managing advanced cases has not yet been established. This study evaluated the efficacy and toxicity of proton beam therapy （PBT） combined with selective intra-arterial infusion chemotherapy （IAIC） using weekly cisplatin for locally advanced ACC of the base of the tongue. Between March 2009 and February 2018, 15 patients were treated. The median follow-up duration was 56 （range: 15-116） months. The 5-year local control and overall survival rates were 89％ and 76％, respectively. With regard to late toxicities, grade 2 osteoradionecrosis was found in one patient and grade 5 pharyngeal necrosis in one patient. Considering most cases were signi?cantly advanced and inoperable, this therapy was effective in controlling the primary tumor, preserving function and maintaining quality of life. Although improvements are needed to reduce adverse events, PBT in combination with IAIC can be a treatment option for locally advanced ACC of the base of the tongue.

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Virtual touch tissue imaging quantification （VTIQ） is an elastography technique that measures the tissue elasticity quantitatively as the propagation velocity （Vs） of shear waves and displays tissue elasticity images. We analyzed the histological relationship of 51 salivary gland tumors whose VTIQ was measured and pathologically diagnosed from 2016 to 2019 at Fukushima Medical University Hospital. There were 11 malignant tumors, 21 benign tumors with pleomorphic adenoma, and 19 other benign tumors, and Vs and tissue elasticity images were compared among the three groups.
Vs of 4.8m/s or higher was 45％ overall, 91％ for malignant tumors, 55％ for pleomorphic adenomas, and 0％ for other benign tumors. Vs for pleomorphic adenomas had a large range and was difficult to distinguish from that for malignant tumors. The tissue elasticity images of each tumor were classified into four types: 91％ of malignant tumors and 10％ of pleomorphic adenomas were the homogeneous type or geographic type, and 9％ of malignant tumors and 67％ of pleomorphic adenomas were the mottled type. Although it was difficult to discriminate by Vs, it may be possible to discriminate between malignant tumors and pleomorphic adenomas by tissue elasticity images.

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A clinicopathological study, focusing on local recurrence, was performed on 107 patients who were histologically diagnosed with oral squamous cell carcinoma and who underwent radical surgery at the Department of Oral and Maxillofacial Surgery of Nagoya Ekisaikai Hospital between January 2007 and March 2020. Among these 107 patients, 14 developed local recurrence with a recurrence rate of 13.1％. The median interval between surgery and local recurrence was 293.5 days （range: 21-1,408 days）. An analysis of the risk factors for local recurrence was performed, and depth of invasion was identified as an independent risk factor. Salvage treatments included surgery in 7 patients, radiation and chemoradiotherapy in 4 patients, and palliative care in 3 patients. Seven of the 11 patients （63.6％） were successfully salvaged. Analysis of the patients with local recurrence showed that the surgery resulted in a better outcome. However, further studies are needed to analyze the risk factors for the recurrence and efficacy of the salvage treatments from multiple perspectives.

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For the management of cancer, both complete and careful surveys are important. Because surveys by medical institutes are time-consuming, it is necessary to share the burden among regional institutes while maintaining medical quality. A regional survey system using regional contact paths for five major cancers was started in Japan. Because the number of patients is small, the same system for thyroid cancer is not strongly recommended. On the other hand, regional surveys for thyroid cancer are suitable because the postoperative prognosis is good, and long-range surveys are necessary. From 2014 to 2019, 76 cases operated for papillary thyroid cancer at our institute were applicable to this system using a regional contact path. On the other hand, 304 cases were not applicable to this system. Not so many regional institutes complied with our request because of their experience of management of papillary thyroid cancer. To promote this system, changes in efforts for surgeons, regional doctors, and patients are required.

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We retrospectively analyzed the frequency of retropharyngeal lymph node （Rp） metastasis on diagnostic images and the irradiation dose to the same area in 55 patients with advanced maxillary sinus squamous cell carcinoma who underwent external radiotherapy and superselective intra-arterial chemotherapy at Juntendo Hospital. Reassessment of pretreatment images revealed potential Rp metastases in 10 patients （18％）; 9 who were diagnosed with a minor axis of ≥ 5mm and 1 diagnosed with a major axis of ≥ 10 mm. Patients who underwent MRI or PET-CT tended to have a high rate of Rp node metastases （P＝0.090）. The median irradiation dose for Rp metastasis was 57.7 Gy, and 8/10 patients were irradiated with high doses without targeting. As a result, no recurrence of Rp metastasis was observed. When the Rp region is not targeted during intensity-modulated radiation therapy, the Rp region dose is significantly lower than that of three-dimensional radiation therapy （47.4 Gy vs. 36.0 Gy, respectively; p＝0.040）.

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Gunma University has been utilizing carbon-ion radiotherapy as a treatment for head and neck cancer since 2010. We evaluated the long-term efficacy and safety of carbon-ion radiotherapy for non-squamous cell carcinoma of the head and neck in 35 patients enrolled in a pective study at the Gunma University Heavy Ion Medical Center （from 2010 to 2014）. The median age of the patients was 59 years （range, 31-77 years）. The median follow-up time for all the patients was 65 months （range, 6.1-98.8 months）. Thirty-two and three patients received 64.0 Gy （relative biological effectiveness） and 57.6 Gy （relative biological effectiveness） in 16 fractions, respectively. The T-classification was 5/8/22 in T2/3/4, respectively, and the tumors were inoperable in 20 cases （57％）. The maxillary sinus and nasal cavity were the most common sites for tumors in 9 cases （26％）. Adenoid cystic carcinoma was dominant, with this carcinoma being found in 21 cases （60％）. The 5-year local control, progression-free survival, and overall survival rates were 74.5％, 53.2％, and 81.3％, respectively. Nine patients had local recurrence, and six patients died. Acute and late adverse events were evaluated according to the Common Terminology Criteria for Adverse Events, version 4.0. Over acute grade 3 radiation mucositis （8 cases） improved immediately with conservative therapy. Late grade 4 adverse events were observed; these were two cases of visual loss and one case of brain necrosis. There were no grade 5 adverse events. Carbon-ion radiotherapy achieved excellent local control and overall survival rates for non-squamous cell carcinoma.

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Hypopharyngeal cancer often coexists with other primary cancers, particularly esophageal cancer. Making a treatment choice for patients with synchronous double cancer may be difficult, and the treatment may not be performed as scheduled. We examined 152 patients with hypopharyngeal cancer receiving first-line therapy in our hospital from January 2011 to December 2014. Eighty-four patients had double cancer （55％）, and the most common second malignancy was esophageal cancer, which showed both synchronous and metachronous associations. The 5-year overall survival （OS） of patients with hypopharyngeal cancer alone （n＝68） and that of those with hypopharyngeal and esophageal cancers （n＝52） were 54％ and 80％, respectively, with a significantly better survival in patients with double cancer. This was presumably because of the early detection of hypopharyngeal cancer using upper endoscopy in patients with double cancer. Regarding synchronous double cancer comprising hypopharyngeal and esophageal cancers, the OS rates were 100％, 65％, 75％, and 56％ for patients with early-stage hypopharyngeal and esophageal cancers, advanced hypopharyngeal and esophageal cancers, early-stage hypopharyngeal and advanced esophageal cancers, and advanced hypopharyngeal and early-stage esophageal cancers, respectively. Early-stage esophageal cancer cannot be treated early, and chemotherapy may be administered as a first-line treatment. Even if early-stage hypopharyngeal cancer responds to previous chemotherapy, a close follow-up or treatment is required.

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Supracricoid laryngectomy （SCL） is a useful surgical procedure that enables both disease cure and function preservation in patients with laryngeal cancer, however, the duration of treatment tends to be prolonged. We report an attempt to start swallowing rehabilitation at an early post-operative time where feasible to shorten the duration of treatment.
All 31 patients who underwent SCL for laryngeal cancer in our hospital from March 2013 to August 2020 were included. The cases were divided into those in which swallowing rehabilita-tion was performed before the tracheostomy closure （early rehab group, n＝7） and those in which it was performed afterward （late rehab group, n＝24）. The timing of postoperative intervention and the total duration of treatment were compared between these two groups.
In the early rehab group and the late rehab group, the median start dates of swallowing rehabil-itation were 20 days （range, 15-24 days） and 71.5 days （33-227 days） after surgery, re-spectively （p＜0.001）. The median duration of swallowing rehabilitation was 28 days （16-88 days） and 22 days （12-77 days）, respectively （p＝0.15）. The median total duration of treatment was 54 days （45-109 days） and 108.5 days （63-441 days）, respectively （p＜0.001）.
Initiation of swallowing rehabilitation before tracheostomy closure significantly shortened the total duration of treatment without extension of the duration of swallowing rehabilitation. This procedure may be a practical and useful intervention in the postoperative management of SCL.

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A 41-year old man with nasopharyngeal adenoid cystic carcinoma （T4aN0M0） received carbon ion radiotherapy of 65 Gy （RBE） in 25 fractions. The treatment was well tolerated and complete response was obtained. At 30 months after the therapy, mucosal necrosis and brain necrosis were observed as a late toxicity. Despite treatment with oral steroid, brain necrosis worsened and osteonecrosis of the skull base and cervical spine was newly observed. The patient died of intracranial infection caused by mucosal necrosis, brain necrosis and osteonecrosis of the skull base and cervical spine at 54 months after the carbon ion radiotherapy. A pathological autopsy revealed no recurrence of adenoid cystic carcinoma. Carbon ion radiotherapy may be a useful treatment option for radioresistant malignant tumors of the head and neck. Optimal treatment planning and long-term careful follow-up are necessary to control fatal late toxicities.

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We encountered a patient who underwent cochlear implant surgery for bilateral severe hearing loss after administration of cisplatin. The patient was a 69-year-old man who received cisplatin and vinorelbine as postoperative chemotherapy for lung cancer. On day 7 of administration, the patient experienced hearing loss. On day 9, pure tone audiometry showed bilateral deafness. The patient also developed a renal disorder, but it subsequently improved. As hearing aids were ineffective, cochlear implantation was performed to treat the bilateral severe hearing loss. The patient’s hearing ability was favorable immediately after the implantation. This case shows that hearing loss can be induced by cisplatin after not only dose accumulation but also single administration. Identifying genes related to cisplatin-induced hearing loss to predict post-administration hearing can contribute to a safer cancer treatment plan. Currently, there is no method for predicting or preventing the onset of hearing loss; therefore, cochlear implant surgery may be the only option for patients who develop bilateral severe hearing loss after the first administration of cisplatin.

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A radiation-induced malignant tumor is a malignant tumor that develops at the irradiation site after radiation therapy. The latent period is long and the actual situation has not been fully clarified. Intensity-modulated radiation therapy （IMRT）, which has been on the increase in recent years, exposes many normal tissues to radiation. Therefore, by using IMRT, it is estimated that the incidence of radiation-induced malignant tumors is twice as high as that in the past. Although the case we experienced was not caused by IMRT but by conventional radiation therapy, it is highly possible that radiation-induced malignant tumors will increase due to the increasing number of IMRT cases and increasing use of chemoradiotherapy. It is essential to review the frequency and end time of follow-up and to establish close cooperation with regional medical institutions.

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