Perioperative neutron brachytherapy with californium-252.

Between 1973 and 1988, 495 patients were treated with Cf-252 neutron brachytherapy. Cf-252 neutron therapy sources developed in the USSR has been used in the trial. A numerical reconstruction method for localization of Cf-252 cell coordinates by projections on orthogonal radiographs has been designed and used for treatment planning. Eight (1.6%) patients with recurrent and persistent head and neck tumors and ages from 32 to 48 years (mean age 43 years) were treated with Cf-252 perioperative neutron brachytherapy. There were three patients with oral cavity, one with oropharynx, three with parotid gland cancers, and one with a skin tumor. The dose rate ranged fro 3.2 cGy/h to 11.1 cG/h, the minimal peripheral dose ranged from 3 Gy to 8 Gy. Initial local control was achieved in all patients. Local recurrence developed in two cases. Three patients died in first year after therapy. Three patients died during the second year. Two patients are long term cures, one patient more than nine years and one eight years, that is 25% of the treated patients.

Californium-252 interstitial implants in carcinoma of the tongue.

A clinical study using 252Cf sources in brachytherapy of tumors began in the Research Institute of Medical Radiology of the Academy of Medical Sciences of the USSR in 1973. 252Cf afterloading cells were utilized by the method of simple afterloading. Dosimetry and radiation protection of medical personnel were developed. To substantiate optimal therapeutic doses of 252Cf neutrons, a correlation of dose, time, and treatment volume factors with clinical results of 252Cf interstitial implants in carcinoma of the tongue for 47 patients with a minimum follow-up period of 1 year was studied. Forty-nine interstitial implants have been performed. Seventeen patients received 252Cf implants alone (Group I), 17 other patients received 252Cf implants in combination with external radiation (Group II), and 15 patients were treated with interstitial implants for recurrent or residual tumors (Group III). Complete regression of carcinoma of the tongue was obtained in 48 patients (98%). Recurrences occurred in 1 patient (6%) in Group I, 6 patients (35%) in Group II, and 5 patients (33%) in Group III. Thirteen patients (27%) developed radiation necrosis. The therapeutic dose of neutron radiation from 252Cf sources in interstitial radiotherapy of primary tongue carcinomas (Group I) was found to be 7 to 9 Gy. Optimal therapeutic neutron dose in combined interstitial and external radiotherapy of primary tumors (Group II) was 5 to 6 Gy with an external radiation dose of 40 Gy. For recurrent and residual tumors (Group III), favorable results were obtained with tumor doses of 6.5 to 7 Gy.

Neutron brachytherapy in the treatment of melanoma.

PURPOSE: The use of Cf-252 for treatment of cutaneous malignant melanoma is presented. METHODS AND MATERIALS: From 1975 to 1992, plaque Cf-252 applicator neutron brachytherapy was performed in nine patients with skin malignant melanoma of head and neck or chest wall. Neutron brachytherapy alone was applied in six patients; two patients received neutron brachytherapy before and one after photon teletherapy. Tumor neutron brachytherapy doses ranged from 3.9-11.5 Gy. Four patients underwent surgical resection of the primary tumor and in six cases, regional lymph node dissection was done. RESULTS: The patients survival times ranged from 3 months to 12 years; 2-year survival was 50% and 30% of the patients lived 3 years. The mean survival time was 39 months. All but 1 patients died because of distant metastases. Local tumor control was achieved in all cases. CONCLUSION: The clinical study shows the relative sensitivity of melanoma to the neutron irradiation and offer new possibilities in Cf-252 brachytherapy.

Trace elements and thyroid cancer.

To evaluate the importance of trace amounts of elements in thyroid cancer etiology and diagnostics, instrumental neutron activation analysis has been used to estimate Ag, Co, Cr, Fe, Hg, I,Rb, Sb, Sc, Se, and Zn concentrations in malignant and benign thyroid nodules as well as in apparently intact paranodular thyroid tissue. Resected material from 135 patients was obtained from operations. Forty-five cancer cases were diagnosed and the rest were of benign nodules. The thyroid glands of 65 people, 53 male and 12 female, who died and unexpected death or committed suicide, were used as a control group. Trace element contents of the International Atomic Energy Agency reference material H-4 (animal muscle) were analysed simultaneously with the thyroid tissue in order to evaluate the accuracy of the obtained data. No dependence of trace element contents on sex and age (14-80 years) was found for normal thyroids. In paranodular tissue, the Ag, Co, Hg, I and Rb contents were much higher for malignant and benign nodules than they were for the standard. There was also a slight deficiency of Se in the nodules compared with the standard. This result supports the hypothesis that the direct toxic heavy metal influence on thyrocytes plays a major role in thyroid cancer etiology, provided that an adequate level of the defence mechanisms is absent. Iodine concentrations are 15 times lower, on average, in malignant compared with benign nodules. It is also shown that the radio between the iodine concentration in nodular and paranodular tissue can be used for in vivo thyroid cancer diagnostics.