The histologic grading of mode of invasion in squamous cell carcinoma of the head and neck was first proposed by Jakobsson, et al in 1973. Grade (Gr.) 4 of mode of invasion, i,e., diffuse invasion or diffuse growth, was subclassified by us into Grs.4C (cord-like type) and 4D (diffuse, widespread) for oral squamous cell carcinoma (OSCC), in 1983. Since then, clinicopathological, immunohistochemical and experimental studies for the mode of invasion have been performed to the present. The Gr.4D specific characteristics comparing with Gr.4C were observed in 1) the poorest prognosis of patients in clinical course, 2) disapearance of cell adhesion molecule corresponding with single cell invasion, 3) strong desmoplasia like as scirrhous gastric cancer in histopathology, 4) greater motility as a single cell in vitro, 5) an original strong invasion into even if "non-fibroblast" collagen gel in in vitro invasion model, 6) no up-grading from Grs.4C to 4D in experimentally induced tongue cancer, 7) no cancer invasion orthotopically transplanted into nude or SCID mouse in in vivo invasion model, in contrast to an original invasion in Grs.3 and 4C. It was concluded from these results that Gr.4D is an independent type from any other grades, and consequently, this subclassification in the mode of invasion was proven justifiable. Finally, clinical feature and treatment strategy in Gr.4D cases are discussed.

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We studied 947 patients with ameloblastoma who visited and were treated at the 61 institutions certified as training facilities by the Japan Society for Oral Tumors between 1995 and 2004. Ameloblastoma were reclassified according to the new WHO classification revised in 2005 and the clinicopathological data were analyzed. The patients were 581 males and 366 females. The higher age groups were 20s (18.6%) in male and 10s in female (23.2%). The most frequent and affected location was the molar region (55.6%). The frequent clinical findings were pain (46.6%) and swelling (13.6%). Radiographically, unilocular appearance was observed in 50.7 %, multilocular appearance was seen in 40.4%. Histopathologically, solid/multicystic type was observed in 74.5%, unicystic type in 17.0%, desmoplastic type in 4.1%, and extraosseous/peripheral type in 3.0%. The treatment modalities for ameloblastomas were both conservative surgery (74.0%) and radical ones (24.1%).

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A questionnaire survey on radiotherapy for oral cancer at 29 oral and maxillofacial radiology departments in Japan was performed. In 11 departments, 35 oral and maxillofacial radiologists worked at radiotherapy. Of the patients, 285 were treated by external radiotherapy and 158 by brachytherapy. In both treatments tongue cancer was the most frequent. The total of 443 patients was estimated to be about 9% of all oral cancer patients in Japan, and the 158 patients treated by brachytherapy to be about one half of all head and neck cancer patients treated by brachytherapy in Japan. In recent years, the incidence of cancer has been increasing and more frequent use of radiotherapy is encouraged. Radiotherapy for oral cancer is expected to play an increasingly important role.

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Purpose: To analyze the treatment results of low-dose-rate (LDR) or high-dose-rate (HDR) interstitial brachytherapy (ISBT) for early (T1N0, T2N0) mobile tongue cancer using microSelectron-HDR (Nucletron, Veenendaal, the Netherlands) in our institute.
Methods: Patients with squamous cell carcinomas of the early mobile tongue were treated with low dose rate (LDR) ISBT or microSelectron high dose rate (HDR) ISBT at the Department of Radiology, Osaka University Hospital. In the case of LDR-ISBT, all cases were treated with a total of 60 Gy/6 days to 70 Gy/7 days. In the case of HDR-ISBT alone, all cases were treated with a total dose of 54 Gy/9 fractions/5 days or 60 Gy/10 fractions/8 days. In the case of the combined therapy, an external dose of 30 Gy/3 weeks to 40 Gy/4 weeks was irradiated. Brinkman index and alcohol index were used for analyzing incidence of late complications after HDR-ISBT.
Results: HDR-ISBT showed the same local control rate as LDR-ISBT (about 80% at 3 years). Elderly patients (65 years or older) showed a poorer local control rate than the younger group (less than 65 years of age). Fifteen of 72 patients (21%) treated with HDR-ISBT had late complications. Ten of 15 patients (67%) with late complications had a Brinkman index of more than 600.
Conclusions: HDR-ISBT achieved the same results as LDR-ISBT for early tongue cancer. However, elderly patients showed a higher rate of local recurrence after ISBT. In addition, we found an increase in late complications, such as soft tissue ulcers and/or bone exposure, after irradiation of 60 Gy HDR-ISBT for tongue cancer when the patients had a Brinkman index of more than 600.
Fuwa et al. reported that the results of arterial injection therapy using cisplatin with sodium thiosulfate were excellent. Therefore, this chemoradiotherapy may be a new therapy for advanced tongue cancer or surgically inoperable cases in the future.

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Super-selective intra-arterial infusion chemotherapy using cisplatinum (CDDP) has been an established organ-preserving therapy for squamous cell carcinoma of the head and neck region. We have observed a constant treatment response in advanced cases by combined intra-arterial and systemic chemotherapy. Our protocol consisted of intra-arterial infusion of docetaxel (DOC) by the Seldinger method on day 1 followed by intra-venous instillation of CDDP for one day, and continuous infusion of 5-fluorouracil (5-FU) for 5 days from day 2. Radiotherapy was administered from day one until the total dose exceeded 60 Gy. The three-years overall survival rate of stage III–IV disease was 69%. As for adverse reactions in grade 3–4 diseases, leukopenia was noted in 70% and mucositis in 47%. For intra-arterial infusion chemotherapy, detailed anatomical knowledge and identification of a feeding artery are necessary to eradicate the tumor with no neurological events. To clarify the role of the intra-arterial infusion chemotherapy in the treatment system, multi-institutional clinical trials are now being planned.

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Cutting Field IMRT (CFIMRT) is a radiation technology which was developed for distributing the dose of IMRT in combination with an already established radiation method. Because a microscopic irradiation field such as IMRT is not used, its reproducibility and scope of usage are considerably enhanced, facilitating optimal therapeutic planning with the aid of templates so far proposed in various fields. Furthermore, CFIMRT has the merit of flexibility, thus absorbing the potential difference in instruments used in various institutions, and so can be used even in a facility with no MLC. In particular, its clinical application to the head and neck region where the target capacity and critical organs are anatomically close and in complicated juxtaposition with each other is highly expected in many institutions.

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Human T-cell leukemia virus type 1 (HTLV-1) is known to cause adult T-cell leukemia (ATL). Several cases of ATL in the oral cavity have so far been reported. In addition, because ATL has been frequently reported to be complicated with solid cancer, ATL should be ruled out in patients who are HTLV-1 carriers and who are suspected of having an oral malignant tumor.
A 44-year-old female who was an HTLV-1 carrier presented with a two-week history of a mass on her tongue. Our initial examination revealed a 30 × 20mm, indurated mass on the left side of the tongue. The laboratory data indicated anti HTLV-1 antibody to be positive and atypical lymphocytes were detected in 1% of the white blood cells in a blood smear preparation. The clinical-diagnosis was a malignant tumor in the tongue. A tongue biopsy revealed squamous cell carcinoma. Polyclonal integration of HTLV-1 proviral DNA was detected by Southern blotting of both a biopsy specimen and peripheral blood, thus ATL could be ruled out.
The preoperative diagnosis was tongue cancer (T2N2bM0). A tongue sub-total resection and left neck dissection and reconstruction were therefore performed. During adjuvant radiotherapy, right cervical lymph node metastasis appeared. As a result, a right neck dissection and adjuvant radiotherapy to the right neck were performed. Unfortunately, bone and lung metastasis occurred and the patient died 12 months after our initial examination.
These findings suggest that a chronic HTLV-1 infection may therefore compromise cellular immunity, thereby accelerating the progression of cancer.

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