This review will be discussed the various causes of radiation failure for head and neck cancers from radiobiologic perspective and also provided a few clinical data to illustrate the basic principle. A knowledge about multiplicity of factors that may underlie failure of radiation treatment is essential for rational application of new treatment strategies. Furthermore, it is important to distinguish causes of failure that can be reduced or minimized by application of conventional treatment from one are potentially remediable by new treatment strategies, and one that are not amenable to some modification of radiotherapeutic approach.

Systemic chemotherapy is usually regarded as the standard treatment for palliation in patients with recurrent or metastatic cancer who have failed the definite local treatment with surgery and/or radiotherapy. Recently, with the introduction of more active chemotherapeutic agents and combinations, systemic chemotherapy is being increasingly used before or after local therapy in patients with previously untreated locally advanced head and neck cancer. The most active agents for the head and neck caner are methotrexate, 5-fluorouracil (5-FU), cisplatin and bleomycin. The overall response rates to each of these four drugs are 15-30% expecially when used as first line therapy. But most of these responses are partial with a mean duration of 3-5 months. Various combinations with methotrexate, 5-FU, cisplatin, and bleomycin have been tried with overall response rates of 50-90%, and 10-20% of complete responses. The introduction of chemotherapy prior to local therapy, induction chemotherapy, has been investigated with improved survivals in patients with complete response, especially pathologic, though improvement in overall survival has not been proved yet after the induction chemotherapy. Other therapeutic modalities, such as 'Sandwich' chemotherapy between surgery and radiotherapy, concomittent chemo-radiotherapy and post local treatment adjuvant chemotherapy have been pursued with some hopeful results but these trials should be compared with prospective randomized Phase III trials. To increase the response rates and enhance the survival, important work still remains; 1. Identification of better prognostic factors, 2. Improvement in staging, 3. Development of more active and safter chemotherapeutic agents, 4. Identification of the proper sequence for the addition of chemotherapy to multimodality treatment, and 5. Testing the value of such chemotherapy in locally advanced cancer patients.

It is well known that laryngeal papilloma has a tendency for malignant transformation, but the incidence was variable among many authors. The authors present a case of laryngeal cancer which was considered to be transformed from laryngeal papilloma after six years follow up, with serial pathological review of the specimen. Incidence of malignant transformation in our hospital is 2.5% of total laryngeal papilloma and it is the only case among 57 laryngeal cancer for 6 years duration. It must be stressed that long term follow up is recommanded in adult type laryngeal papilloma.

Dermoid cyst of the floor of mouth is infrequent. This cyst has been classified as epidermoid, dermoid and teratoid cyst. Dermoid cyst is more common in young adults and no sex predilection and has generally been present for months to years before progressive enlargement causes interference with the mobility of the tongue and disturbance of articulation and mastication. The authors have recently experienced dermoid cyst of the floor of mouth which was confirmed histopathologically.

This is a retrospective analysis of 8 patients with olfactory neuroepithelioma treated by external radiation during 1981-1988. Their age ranged from 13 to 65 years. All of them were male patients. At the time of diagnosis, six patients were classified as Kadish stage C, two were stage B, and none of them were stage A. Six of eight patients treated by external irradiation, only one patient had complete surgical resection followed by postoperative irradiation. Another one patient received one course of induction chemotherapy followed by radical irradiation. Three patients developed local recurrences and five patients had distant metastasis. One patient with stage B disease who had complete surgical resection followed by postoperative irradiation was alived without evidence of disease. Seven of eight patients died of tumor, with a duration of survival ranging from 3 to 106 months.

Thirty five lesions of 35 patients with locally advanced malignant tumors of head and neck were received thermoradiotherapy with ultrasound and/or 915 MHz microwave. Most of all patients were failed with previous conventional therapeutic trial. Hyperthermia had been done immediately after radiotherapy, twice a week, $43^{\circ}C$ for one hour and radiotherapy had been done 5 fractions per week with a fraction size of 2 Gy up to total 30 to 60 Gy. Conclusions are as follows; 1) Total response rate (CR+PR) of thermoradiotherapy with microwave and ultrasound was 80%. 2) Tumor depth, minimum temperature of tumor center, number of heat fraction and irradiation dose were statistically significant factors affecting response. 3) Hyperthermia with microwave and ultrasound can be used efficiently to control locally advanced malignant tumors in head and neck whether previously received near tolerance dose of radiotherapy or not.