Tetsuya Shima

Laserthermia on Head and Neck Malignancies— Experimental and Clinical Studies

In recent years, remarkable progress has been made in thermotherapy. However, there is little information on localized laser hyperthermia (laserthermia) or on conventional hyperthermia technique applied to head and neck cancers. We have developed a ceramic probe to insert into tumor tissue and irradiate the Nd:YAG laser omnidirectionally. This probe can heat a spherical range of 1.5 cm to 43 degrees C. This paper concerns experimental and clinical studies on the effectiveness of laserthermia using our technique in the tumor of head and neck regions. The results obtained were as follows: histological findings and biochemical studies of arachidonic acid metabolites on normal rabbit tongue after laserthermia showed very slight effect and relatively short duration of the concomitant inflammation. The combination of laserthermia and CDDP chemotherapy was found to give a much better cytocidal effect on the tumor tissue in nude mice implanted with human thyroid cancer cells. In a clinical study on 21 cases with head and neck cancers, four cases showed complete and 13 cases showed partial remission after combined treatments of laserthermia and radiochemotherapy. Both basic experimental and clinical results have indicated a role for laserthermia in the treatment of head and neck cancer. Possible uses include the treatment of early cancer as well as advanced or recurrent cancer, where its therapeutic effect may be increased by combination with radiotherapy or chemotherapy.

Laser Beam in Treating Congenital Choanal Atresia in Three Patients

We present the results of 3 patients with congenital unilateral choanal atresia who were treated surgically at our department. We report a method of surgical approach for repair of choanal atresia. A transpalatal procedure offers an approach which is straightforward. The use of carbon dioxide or Nd:YAG laser seemed better for recurrent cases. A tube stent should be placed for at least 6 weeks postoperatively.

Histological changes in elastic components of soft palate scars after CO2 and contact Nd:YAG laser incisions in the dog as an experimental model

Soft palate stiffening operations — often with CO2 or contact Nd:YAG lasers — have been used recently to treat patients with pronounced snoring. Differences in soft palate scars formed after CO2 and contact Nd:YAG laser incisions were studied in an animal model to determine which of these lasers produces a more rigid scar and consequently might be more effective for a soft palate stiffening operation. Six mongrel dogs were placed in each laser group, after which either the CO2 or Nd:YAG laser was used to make a 1.5-cm-long soft palate incision. The scars produced were then excised and studied histologically 4 weeks postoperatively. Special attention was paid to collagen density and elastin fibers in the scar tissue. After contact Nd:YAG laser incisions scar tissue was found to contain densely aligned collagen fibers and practically no elastin fibers. CO2 laser incisions produced significantly different scars: irregularly arranged collagen fibers with some elastin fibers also inside the scar tissue. Differences in the shapes of the scars and wound contractions were also found that were only seen after contact laser incisions. These findings suggest that the contact Nd:YAG laser might be more effective for soft palate stiffening operations.

Localized Hyperthermia Using Contact YAG Laser in the Treatment of Head and Neck Cancer

It is well known that hyperthermia combined with radio-chemotherapy can be useful in treating malignant tumors. This treatment using micro-wave or radiofrequency has been limited to thraco-abdominal malignant lesions. The main advantage of this technique is the administration of irradiation or heat to a limited tumor volume, sparing the surrounding normal tissues. However, there is little information on localized laser hyperthermia therapy applied to head and neck tumors. We have recently developed a new ceramics-tip for localized laser hyperthermia.