Preliminary results of fast neutron teletherapy of metastatic cervical adenopathy

Fast Neutron Irradiation in Advanced Pre-Irradiated Head and Neck Tumors

Aims and background

Radiotherapy with fast neutrons offers radiobiological advantages in the treatment of hypoxic and slowly proliferating tumors. Tumors recurring in pre-irradiated areas of the head and neck usually exhibit a low radiation sensitivity that seems to promise little success for a repeated irradiation with photons. In such a situation, radiotherapy with fast neutrons may offer an alternative treatment option. To evaluate the question, the Muenster patients were retrospectively analyzed.

Methods

During the period July 1986 to January 1994, 26 patients with local-regional recurrences of pre-irradiated head and neck tumors were treated with fast neutrons at our department.

Results

Median survival calculated by the Kaplan-Meier method was 7.4 months. The 1-year survival probability was 29.3% and the 2-year survival probability 5.9%. The objective tumor remission (complete + partial) was 50%. A subjective improvement of symptoms was reported by 42.3% of all patients.

Conclusions

Despite relatively unfavorable survival rates produced by the therapy, good remission rates and thereby a good palliative effect can be attained with a short treatment time and tolerable side effects.

Particle radiation therapy

Current interest in attempting to identify any therapeutic advantages of beams of heavy particles (heavier than electrons) over photons is based on differences in physical absorption and radiobiologic interactions. The article discusses: dose distributions in tissue, which are markedly different for particles than for high energy photons and so may be clinically advantageous for the former; differences in radiobiologic responses, which could lead to increased tumor cell killing and a possible increase in the therapeutic ratio for particles; clinical experience to date; directions for and impediments to future research.

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.

Fast neutron irradiation of metastatic cervical adenopathy: the results of a randomized RTOG study

Between 1977 and 1982, 199 evaluable patients with measurable cervical adenopathy were entered on a prospective, randomized RTOG study evaluating the use of fast neutrons in treatment of advanced, inoperable squamous cell carcinomas of the head and neck region. One hundred-eleven patients were randomized to receive mixed beam radiation therapy, and 88 were randomized to the photon control treatment. The complete response rates were 86% for mixed beam vs 75% for photons for Stage N1 nodes, 62% for mixed beam vs 48% for photons for Stage N2 nodes, and 63% for mixed beam vs 53% for photons for N3 nodes. The percents of patients remaining free of their adenopathy for two years were 78% for mixed beam vs 55% for photons for Stage N1 nodes, 39% for both mixed beam and photons for N2 nodes and 24% for mixed beam vs 13% for photons for N3 nodes. The median disease-free status was 20.3 months for mixed beam treated patients and 6.4 months for photon-treated patients. Patients who had clearance of cervical adenopathy survived significantly longer than those who did not.

An evaluation of fast neutron beam teletherapy of metastatic cervical adenopathy from squamous cell carcinomas of the head and neck region

One hundred thirteen patients with metastatic cervical adenopathy (MCA) from advanced squamous cell carcinoma of the head and neck completed fast neutron beam irradiation between September 1976 and March 1977. With a maximum follow-up time of 49.9 months (mean 14.5 months), 54% of the total group remain disease-free at the sites of their cervical adenopathy. Control of adenopathy measuring 3 cm or less in maximum dimension was 75% with neutrons only and 87.5% with mixed beams. Nodes measuring 3-6 cm were controlled 38.1% of the time with neutrons only and 59% of the time with mixed beams. Clinical control of adenopathy measuring greater than 6 cm was obtained in 12.5% with neutrons only and 29.4% with mixed beams. For patients with controlled primary tumors, the overall control rate in the neck was 72%; 100% of nodes 3 cm or less were controlled, 82% of nodes measuring from 3-6 cm were controlled, and 42% of nodes greater than 6 cm were controlled. Patients with controlled primary tumors treated with mixed beams had 100% control of nodes measuring 3 cm or less, 96% control of nodes measuring 3-6 cm, and 50% control of nodes measuring greater than 6 cm. Overall, the control rate for mixed beams was significantly better than for treatment with neutrons only. Morbidity was less (both acute and late) in the mixed beam-irradiated group.