More than 10 years have passed since the da Vinci® Surgical System （Intuitive Surgical Inc.） was introduced to head and neck cancer treatment. It has spread all over the world very quickly and the indications for this procedure have been expanding.
Trans-oral robotic surgery （TORS） was initially applied to oropharyngeal cancer （anterior wall and lateral wall）, and is now widely used for naso- and hypo-pharyngeal cancer treatment. Although its indications remain open to discussion, TORS demonstrates good accessibility and operability for nasopharyngeal cancer. As for hypopharyngeal cancer, it is still difficult to obtain good exposure of the hypopharynx. However, new instruments have been shown to work in the hypopharynx, and the difficulty of exposing the hypopharynx will be addressed by making the instruments smaller.
In Japan, a multi-institutional clinical study of TORS was completed last year, and the use of surgical robots has just been approved in the field of otolaryngology. Currently, in order to ensure the quality and safety of TORS, related societies are preparing rules and systems for conducting TORS.

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Immune check point inhibitors （ICPi） have shown activity not only in malignant melanoma but also in lung cancer, renal cell carcinoma, urothelial carcinoma and so on. With regard to head and neck cancer （HNC）, ICPi improves survival for platinum refractory HNC and many clinical trials of ICPi for HNC are ongoing. In Japan, nivolumab, one of the PD-1 antibodies, has been approved since March 2017 and can now be used in clinical practice. On the other hand, ICPi may cause immune related adverse events （irAE）, sometimes resulting in severe sequelae. Thus, it is essential for medical oncologists to be involved in the clinical practice of head and neck cancer patients and to support head and neck surgeons and oral and maxillofacial surgeons. In order to promote such collaboration, the Japanese Society of Medical Oncology （JSMO） has established the Head and Neck Cancer Collaborative Program.

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Computed tomography（CT）is widely used as the first cross-sectional imaging modality and plays an important role in the management of patients with head and neck cancer. Recent advanced CT imaging techniques can generate additional CT reconstructions and there is increasing evidence to improve the diagnostic evaluation. First, dual-energy CT allows material decomposition so that iodine can be differentiated from soft tissue, and can potentially provide additional further “contrast resolution” to the standard contrast-enhanced CT images. The addition of iodine overlay maps using dual-energy CT scanning to the conventional CT images has increased the specificity for detection of cartilage invasion without compromising sensitivity by laryngeal and hypopharyngeal cancer. Second, bone subtraction iodine（BSI）imaging using 320-row area detector CT scanning is useful for detecting and accurately assessing the extent of bone invasion such as skull base/mandible by head and neck cancer. This technique reduces spatial mismatch using volume scanning with wide-area detector CT and a high-resolution deformable registration algorithm, enabling identification of contrast enhancement in the bone marrow by subtracting the unenhanced CT from the contrast-enhanced CT. Third, additional metal artifact reduction postprocessing, such as single-energy metal artifact reduction（SEMAR）, has been applied to improve overall image quality and increase diagnostic confidence in the assessment of soft tissues near and far from metallic implants. The SEMAR algorithm significantly improves both the objective and subjective image quality, thereby increasing the rate of detection of oral cavity tumors.
As a next step, texture analysis/radiomics using CT imaging is now entering the area of personalized medicine with the development of new techniques to predict prognosis, response to treatment, and outcomes from images and other associated data. These developments will be applied to clinical applications and decision support systems using deep learning algorithms in the near future.

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This review summarizes the presentation of “Emerging topics of PET/CT and PET/MR” at the 43rd Annual Meeting of the Japan Society for Head and Neck Cancer. The topics are: 1） The role of FDG-PET/CT for the evaluation after chemoradiotherapy of head and neck cancer, 2） Quantitative PET/CT and its harmonization, 3） The relationship between tumor heterogeneity and texture analysis, and 4） The role of PET/MR for head and neck cancer.

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Recently, the incidence of oral cancer in Japan has been increasing. Tokyo Dental College started oral cancer screening in cooperation with a local dental association in 1992. Here, we report the actual results of mass screening and individual screening for oral cancer.
Mass screening for the public was performed in each region. Individual screening was performed in a general dental clinic of a cooperating physician. In mass screening, we checked 18,590 subjects from 1992 to 2017; the ratio of males to females was 1：3 and the oral cancer detection rate was 0.13％. In individual screening in Chiba city, we checked 4,369 subjects from 2006 to 2017; the ratio of males to females was 1：2.1 and the oral cancer detection rate was 0.14％. We also detected many potentially malignant oral disorders.
We are now developing an oral cavity cancer navigation system and fluorescence optical equipment, and are planning to perform further activities for the early detection and treatment of oral cancer.

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Neck lymph node metastases frequently develop in early-stage hypopharyngeal carcinoma, necessitating prophylactic neck dissection. This retrospective cohort study preoperatively evaluated 58 patients of pyriform sinus carcinoma with no contralateral neck lymph node metastasis, who underwent total pharyngolaryngectomy with bilateral neck dissection for determining the presence of occult neck lymph node metastasis in the contralateral side. This study compared patients with primary lesions that did and did not cross the midline as well as patients with primary lesions that were and were not limited to the pyriform sinus. This suggests that prophylactic contralateral neck dissection may not be required for patients with primary lesions that do not cross the midline or primary lesions limited to the pyriform sinus.

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The aim of this study was to evaluate the association between ALDH2 polymorphisms and clinicopathological characteristics of Japanese hypopharyngeal cancer （HPC） patients.
We retrospectively reviewed the clinical charts of 63 HPC patients who initially underwent curative intent surgery from 2008 to 2015. ALDH2 polymorphism status was determined using Sanger sequencing. Amount of alcohol consumption was converted using the Sake index.
ALDH2*1/*1, ALDH2*1/*2, and ALDH2*2/*2 were found in 27 （43％）, 36 （57％）, and 0 patients, respectively. The Sake index in ALDH2*1/*2 patients was significantly lower than that in ALDH2*1/*1 patients （75.6±9.2 and 114.0±14.5, respectively; P＝0.03）. In contrast, ALDH2 polymorphism status did not correlate with the prognoses of HPC patients.

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We analyzed a total of 34 cases who had undergone partial hypopharyngectomy with laryngeal preservation followed by free-flap reconstruction surgery in terms of swallowing function and its influencing factors such as the patient’s age, the range of partial resection, the kind of flap tissue, and the postoperative structural changes of the larynx and its surroundings. There was no statistically significant relationship between the patient’s age and the frequency of aspiration pneumonia, but some cases in the long-term follow-up showed increased susceptibility to aspiration pneumonia with age. Although not statistically significant, 45％ of the patients whose resection ranges were so large as to include the arytenoid cartilage suffered aspiration pneumonia.
Jejunal patch graft exceeded other skin flaps in number with 22 cases. There was no relationship between the kinds of tissue for free flap and the tendency toward aspiration pneumonia. The frequency of aspiration pneumonia when reconstruction of the aryepiglottic fold was conducted with a jejunal patch graft was no different than when conducted with skin flaps.
As to the morphological changes of the surroundings of the larynx after reconstruction surgery, it was confirmed that a mucosal ridge between the aryepiglottic fold and the pyriform sinus was effective for preventing laryngeal penetration. Also, it seemed important to secure a broad space between the base of the epiglottis and the wall of the pharynx.

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Follicular dendritic cell sarcoma （FDCS） is a rare malignant neoplasm arising from antigen-presenting cells in B-lymphofollicles and can be found at nodal or extranodal sites.
We report a case of nodal FDCS of the neck. A 65-year-old female presented with a left neck tumor. Upon the initial diagnosis of metastatic cervical lymph node of unknown origin, neck dissection was performed. The postoperative pathological diagnosis was FDCS. Complete resection was performed, but we added radiotherapy as adjuvant therapy, because of reduction of locoregional recurrence rate. The patient is currently disease free after 18 months.
With rare diseases such as FDCS, it is difficult to decide not only the diagnosis but also the appropriate treatment. In order to establish the treatment in future, more FDCS cases need to be accumulated. We hope this case report will help to establish the treatment.

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Due to various functional disorders and adverse events with head and neck cancer treatment, the QOL of cancer survivors markedly decreases. In many cases, there is a gradual improvement in QOL, though patients experience various discomforts daily. A critical issue is how long long-term survivors can continue to manage their oral condition. Since 2012, cooperating cancer dentists have been registered and presently there are more than 14,000 such dentists in Japan, creating a framework for referring such cancer patients to dentists in general practice.
In 2011, for patients who were treated from 2007 to 2010, we performed a survey of continued oral management after discharge from Hokkaido University Hospital. After discharge, 34.3％ of cases continued oral management, but when limited to patients in the care of general practice dentists, the rate was only 7.5％. In this study of patients from 2011 to 2016, the patients who continued oral management after discharge and the patients in the care of general practice dentists were higher, at 70.5％ and 40.4％.
It is essential that appropriate oral management in cooperation with local dental clinics is continued to improve the QOL of head and neck cancer patients.

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