Masayuki Kaneko

Role of radiotherapy for mucoepidermoid carcinoma of salivary gland.

This report analyzes 61 patients with mucoepidermoid carcinomas of the salivary gland treated by surgery alone or by surgery plus radiotherapy. Local control for all 61 patients at 5 and 10 years was achieved for 88.8 and 79.7% of the cases. Although the rate of positive surgical margin was higher in patients treated with surgery and radiotherapy (radiotherapy group) than in patients treated by surgery alone (surgery group), the local control rates of the two groups showed no statistically significant differences. There was no local recurrence in seven patients receiving post-operative radiotherapy above 55 Gy while there were three local relapses among 17 patients receiving 55 Gy or lower doses (P < 0.05). The 5- and 10-year actual survival rates were 73.4 and 63.3% respectively. Histopathologic subtype of mucoepidermoid carcinomas correlated with regional lymph node involvement and survival. There were no differences in the local control and survival rates of patients with major salivary gland tumors and patients with minor salivary gland tumors. Radiotherapy using 55 Gy or more combined with operation achieved local control and survival rates comparable with complete resection of tumors even if a positive surgical margin was more frequent in the radiotherapy groups.

Microradiographic and microscopic investigation of a rare case of complex odontoma

An extremely rare case of odontoma that erupted into the oral cavity is presented. The lesion was surgically removed from a 14-year-old girl and examined by soft x-ray radiography, microradiography, and microscopy to determine whether the lesion was complex or compound. Macroscopically, the surface of the lesion was slightly lobular and solid, resembling the surface of an osteoma. The soft x-ray radiograph obtained from the surgical specimen showed radially arranged radiopaque spicules. Microradiographically, dentin was shown to be present in relatively large quantities and to form the bulk of the tumor, with irregular enamel and cementum in small quantities. There were numerous, comparatively well-formed, enamel-free, toothlike structures in the peripheral region of the tumor. Microscopically, the toothlike structures were seen to be arranged radially; this corresponded to the microradiographic findings. Each structure consisted of a central core of pulp tissue encased in a shell of dentin. In the central area of the mass, there was an irregular conglomerate of dentin, enamel, cementum, and pulp tissue. The findings showed that the lesion was a complex odontoma.

Effect of treatment time on outcome of radiotherapy for oral tongue carcinoma

PURPOSE To investigate the importance of total treatment time on the outcome of external beam radiotherapy (EBRT) followed by internal brachytherapy for the treatment of oral tongue carcinoma. METHODS AND MATERIALS Ninety-four patients with T1-T2N0 squamous cell carcinoma of the oral tongue were treated using 35-40 Gy EBRT followed by 35-40 Gy interstitial (137)Cs brachytherapy between 1985 and 1995. The interval between the end of EBRT and the start of interstitial treatment varied for numerous unavoidable reasons, with a mean of 25.3 days and standard deviation of 3.5 days. The median follow-up period was 59.1 months (range 6-146). RESULTS The actuarial survival rate of all cases was 78.4% at 5 years. The 5-year local control rate for those with T1 and T2 was 92.8% and 62.7%, respectively (p < 0.05). The local control rate of the primary tumor in patients with a total treatment time >43 days was statistically lower than that of patients with a total treatment time < or =43 days in all patients (p < 0.05) and in the subgroup of Stage T2 patients (p < 0.05). Multivariate analysis revealed that the local control rates in all cases were significantly related to the T stage (T2 or not), total treatment time (>43 days or not), and location of disease (posterior or not). Regression analysis for 5-year local control as a function of treatment duration showed a 2% loss of local control per day of treatment extension >30 days (r = 0.94, p < 0.01). CONCLUSION The total treatment time was associated with the local control rate in the RT of oral tongue carcinoma. The loss in local control was estimated to be 2.0% per additional day in our series for oral tongue carcinoma.

ESR detection of OH radicals generated inside cells by X-ray and evaluation of the cytotoxicity of DMPO

An attempt was made to identify OH radicals inside cells in which the radicals were generated by X-ray radiolysis. In the experiments, HL60 cells were incubated for 1 hour in a medium containing 100mM 5,5-dimethyl-a-pyrroline-1-oxide (DMPO). Cells were subjected with 20Gy radiation exposure after which the cells were centrifuged. The centrifuged cells were packed in an ESR quartz column and the ESR spectrum was measured. The ESR spectrum of OH radicals was obtained 5 minutes after the irradiation; however, the ESR spectrum of DMPO-OH was weak and decreased rapidly with time in this cell-containing system. The results indicate that the main difficulty in applying the spin-trapping technique to oxygen-derived radicals formed in cell arise from the chemical instability of the resulting spin adducts. To improve the technique to study cellular systems, it will be necessary to increase the stability of the generated spin adduct.

Unhealed old maxillary fracture left for 12 years in a 34-year-old man

A 34-year-old man had a posttraumatic maxillary fracture, which was left to take its own course for over 12 years. The only subjective clinical symptom was slight mobility of the anterior maxillary alveolus when the patient ate hard food with the maxillary teeth. The patient was treated by open reduction and fixation with a good functional result. In this case, the fracture line was detected on a preoperative computed tomography scan only after changing the window level and window width. It is important to bear in mind that an undiagnosed old maxillary fracture is not easily identified on radiological examination.