Clinical evaluation of neutron beam therapy. Current results and prospects, 1983

Fast neutron radiotherapy for primary mucosal melanomas of the head and neck

BACKGROUND

Primary head and neck mucosal melanomas (HNMMs) are rare tumors managed with surgery and/or radiotherapy and associated with poor outcomes. Given their radioresistance, high linear energy transfer radiotherapy with neutrons may improve local control.

METHODS

We conducted a retrospective review of 14 patients with HNMM treated with neutrons at the University of Washington from 1990 to 2012. Five patients had T3 disease, 9 had T4 disease, 3 had regional nodal disease, and 4 had distant metastases at diagnosis. Primary sites were sinonasal (n=10), lip (n=2), and palate (n=2). Ten patients had initial surgical resection/debulking.

RESULTS

Nine patients had gross residual disease, 6 had complete response, and 3 had partial response. Local control was achieved in 79% until death or last follow-up, and 50% developed distant metastases. Kaplan-Meier 5-year local control was 66% and overall survival was 21%.

CONCLUSION

High rates of locoregional control were achieved with neutrons, despite the presence of gross disease. Survival was limited by early distant metastases.

Palliative radiotherapy of malignant melanoma with reactor fission neutron therapy (RENT): a prospective study

To study the efficacy and safety of relatively low-dosed reactor fission neutron therapy (RENT) at the research reactor of the Technical University Munich, we treated 33 superficial lesions of 20 patients with advanced malignant melanoma by neutron beam alone (n = 22), mixed neutron/electron beam (n = 5), or by neutron beam after incomplete surgery (n = 6). Median tumor volume was 17.0 cm3. Median dose for neutron beam alone was 8.0 Gy and for mixed beam 3.0 Gy n + 45.3 Gy e-. Local tumor response, local control time, survival and treatment related toxicity were followed prospectively over a time period of 52 months. Overall response rate (CR;PR) after neutron beam alone and mixed beam therapy was 64% (CR: 36%) and 100% (CR: 60%), respectively. Observed differences between complete (CR) and incomplete (PR, NC) responding lesions were as follows: median tumor volume: 2.0 vs. 51.5 cm3, local control time: 13.3 vs. 3.7 months, median survival: 19.8 vs. 9.0 months. No severe acute or late sequelae could be observed. In conclusion, low-dosed RENT is an effective and well tolerated palliative treatment of superficial malignant melanoma utilizing the biologic advantage of diminished cellular repair capacity. Because melanoma lesions of small size (< or = 6 cm3) tend to respond completely, neutron beam should be performed at an early stage.

Late results in patients treated with pi-mesons for bladder cancer

BACKGROUND

The treatment of bladder cancer with 60 converging pion beams was expected to have certain dose-distribution advantages with possibly fewer side effects than other high linear-energy-transfer (LET) radiation therapies, such as neutrons.

RESULTS

Early results were promising: 20 of 24 (83%) evaluable patients with sessile invasive bladder carcinomas had clinically complete responses. However, only 3 of 10 (30%) evaluable patients with superficial bladder tumors had clinically complete responses. This article reports the long-term follow-up (6-8 years) of these patients with emphasis on the late side effects of pion radiation therapy. Thirty-eight of the 41 (93%) patients treated died after a median survival time of 17 months (range, 4-98 months). Seventeen (45%) died of metastatic disease (in two instances, this was combined with a local recurrence) 5-27 months after radiation therapy. Four (10%) died of locally progressive disease, and eight (21%) died of late side effects of radiation therapy 9-98 months after treatment. All these patients were treated with more than 33 pion Gy and had generally a symptom-free interval of 9-18 months. The observed side effects were severe, consisting of chronic inflammation and vascular damage in the pelvic region often followed by ulceration, fistulas, and perforations throughout the intestines. In 11 patients, cystectomy and urinary diversion was necessary because of excessive fibrosis and bladder shrinkage. In eight patients, a colostomy was required for stenotic inflammatory disease, necrosis, and perforations of the intestines. The remaining nine patients (24%) died of causes unrelated to the primary disease 4-60 months after radiation therapy.

CONCLUSIONS

The results of the first Phase I/II trial using the Swiss piotron showed a high complete response rate in patients with sessile bladder cancers but also a high incidence of local recurrences and severe, in some instances lethal side effects. Although it is expected that these results will be the basis for future improvements, particularly regarding dosing and fractionation, this experience emphasizes the need for a sufficiently long observation period before reaching conclusions about any high LET treatment, such as neutron, pion, or heavy ion radiation therapy.

Cerebral necrosis following neutron radiation of an extracranial tumor

Radiation necrosis of the brain is a rare complication of irradiation for extracranial tumors. We present a patient who emphasizes the potential hazard of neutron therapy, the sensitivity of magnetic resonance imaging (MRI) which may detect white matter changes prior to the development of clinical symptoms, the potential diagnostic value of 18F-fluorodeoxyglucose/positron emission tomography, and the importance of a combined surgical and medical approach for proper treatment.

Soft-tissue sarcoma: neutrons versus photons for post-operative irradiation

Between November 1980 and June 1981, 14 patients with soft-tissue sarcoma were entered into a prospective randomized trial comparing the efficacy of megavoltage photon irradiation with cyclotron-generated fast neutrons as post-operative adjuvant therapy. It became apparent that patients whose primary tumours had been treated with very wide excision, in particular by compartmental resection, suffered severe late tissue damage when subsequently irradiated with fast neutrons. It was therefore decided to terminate the trial after only 14 patients had been entered. Unacceptable late tissue damage may result from the therapeutic use of fast neutron irradiation when applied in these circumstances.

The response of mouse skin to irradiation with neutrons from the 62 MV cyclotron at Clatterbridge, U.K

Acute skin reactions on mouse feet were used to measure the effect of 62 MeV p-Be neutrons from the cyclotron at Clatterbridge, U.K. The results were compared with the response to 16 MeV d-Be neutrons from the cyclotron at Hammersmith, 4 MeV d-Be neutrons from the van de Graaff accelerator at the Gray Laboratory, and 250 kVp X-rays. Up to 16 equal radiation fractions were given alone, or 16 fractions followed by "top-up" doses of 4 MeV d-Be neutrons to study the effect of neutron doses less than 1 Gy per fraction. For equivalent skin reactions, 9-16% more dose (total neutron + gamma) was needed with p(62)-Be neutrons compared with d(16)-Be neutrons. This did not vary significantly between 1 and 16 fractions. The top-up studies indicated that this figure might rise to approximately 14-32% at very low doses of neutrons, the value depending on the method of analysis of the data. The data indicate that the "standard" clinical protocol of 1.47 Gy per fraction (N + gamma dose) in 12 fractions given at Hammersmith with d(16)-Be neutrons would correspond to a dose of 1.64 Gy per fraction (N + gamma) at Clatterbridge using a similar regime of p(62)-Be neutrons. d(4)-Be neutrons were more effective than d(16)-Be neutrons by a factor of 1.6 over the whole range of dose per fraction studied (0.05-14.5 Gy per fraction of d(4)-Be neutrons). Relative to X-rays, the RBE for p(62)-Be neutrons was 1.6 +/- 0.02 for a single X-ray dose of 30 Gy, rising to 2.9 +/- 0.04 for an X-ray dose per fraction of 4.6 Gy given 16 times. The full-course fractionation data and the top-up data together indicate an extrapolated limiting RBE at vanishingly small doses per fraction of 4.2-4.8 depending on the method of analysis. The X-ray data were well-fitted by a linear-quadratic (LQ) model of dose-fractionation, with alpha/beta = 8.6 +/- 1.5 Gy. The LQ model also provides a fairly good description of the neutron responses, alpha/beta being large (greater than 24) reflecting predominantly linear underlying dose-responses for all the neutron beams. This in turn reflects the small variation observed in the relative effectiveness between the 3 neutron beams with changes in dose per fraction.

Results of fast neutron therapy in advanced head and neck cancer

Eighty-nine patients with advanced head and neck cancer were treated with a fast neutron beam of mean energy 5.6 MeV. The standard tumour dose was 1320 cGyn, gamma in 20 fractions over 4 weeks, but 13 patients with laryngeal cancer received 1200 cGyn, gamma. Complete remission was achieved in 50 patients (56%). Fifteen patients (17%) survived 2 years, 14 of them being symptom-free. Survival correlated with the stage of disease. Encouraging results were obtained for cervical node metastases, oropharynx and salivary gland cancer. In laryngeal and hypopharyngeal cancer, neutron therapy seems to be disadvantageous. The main reason for treatment failure was local recurrence. Two patients died of complications.

Neutron interstitial brachytherapy for malignant gliomas: a pilot study

Fifty-six patients with malignant glioma were treated with implantation of the neutron-emitting element californium-252 (252Cf) within 2 weeks after surgical debulking of the tumor. Implantation was performed using computerized tomography-guided placement of afterloading catheters, and the 252 Cf sources were removed after approximately 300 neutron rads were delivered. Patients then received 6000 to 7000 conventional photon rads by external beam. The total photon-equivalent dose to the tumor ranged from 8100 to 9100 rads. The median survival time was 10 months, with 18-and 24-month survival rates of 28% and 19%, respectively. The results of reoperation or autopsy showed that patients had recurrence of the tumor but that radiation necrosis was restricted to the area of the original tumor. Serious complications occurred in five patients (9%) and consisted of wound infections in three, cerebral edema in one, and radiation necrosis beyond the original tumor margin in one. Previous studies using external-beam neutron radiation have shown that neutrons are capable of totally eradicating malignant gliomas; however, in most cases, unacceptable widespread radiation necrosis has resulted. Neutron implants are a logical way to increase the dose to the tumor and decrease the dose to normal brain. Interstitial neutron radiation can be given safely with 252Cf, and the survival results achieved by radiation alone using relatively low doses of interstitial neutron radiation from 252Cf implants plus conventional photon radiation were equal to the results attained with any currently available conventional therapy.

Fast neutron therapy for soft tissue sarcoma

Seventy-nine patients with soft tissue sarcoma were treated with fast neutron therapy at the Hammersmith Hospital, MRC Cyclotron Unit. Sixty-six of these, treated between 1971 and 1983 were assessable. The histology was reviewed and graded in 82% of cases and tumors divided into groups according to maximum diameter. In sixteen patients, who were irradiated following complete macroscopic removal of tumor, there was 94% local control and 86% survived 5 years. Of the 50 patients who had gross tumors present 62% were greater than 10 cm in diameter, and 20 were recurrent after previous radiotherapy or surgery or both. Sixty-eight per cent of gross tumors completely regressed and local control was 52%. The main cause of death was metastatic spread, and median survival was 63 months for Grade 1 patients, 9 months for Grade 2, and 7 months for Grade 3. Thus, there was a significant advantage to patients with Grade 1 tumor but little difference between Grades 2 and 3. Twenty-seven patients experienced late complications of treatment, 67% of which involved the skin predominantly and were related to the low energy of neutrons used. Seventeen of the 27 had received previous radiotherapy. Neutron therapy given in this dose and fractionation produced a higher local control rate than photon therapy, but complications were more frequent. Since these mainly involved the skin a lower level of complications may be anticipated using higher energy neutrons which will have a more even distribution of dose and lower skin dosage. Forty-eight per cent of patients developed metastatic disease, indicating the need for effective systemic therapy, especially in Grades 2 and 3 tumors.

The implications of improved treatment of malignant salivary gland tumors by fast neutron radiotherapy

The conventional treatment for cancer of the salivary glands is surgery, with or without X ray therapy. In advanced tumors (Stage III and IV), local control and 5-year survival rates are less than 35%. Radical surgery severs the facial nerve in the majority of operations on parotid gland tumors. Local control of unresectable salivary gland tumors was achieved, in 74% of cases, by fast neutron therapy. From the MRC cyclotron at Hammersmith Hospital neutrons were given to 65 patients, with locally advanced or recurrent tumors, 89% of which were Stage IV. Local control and 5-year survival rates were 72% and 50%, respectively. The facial nerve was not damaged by neutron therapy. In patients with parotid gland tumors, 77% regained or maintained function. Function was lost in 14% through recurrence and 9% remained paralyzed. The results were achieved using beams from primitive machines with serious disadvantages. The results from neutrons implicate improvements for locally advanced tumors of non-epidermal origin in other sites of the body, especially with the high energy neutrons now available from modern cyclotrons.

Neutron therapy for malignant tumours of the salivary glands. A report of the Edinburgh experience

A group of 28 patients with malignant tumours of the salivary glands have been treated by d(15) + Be neutron irradiation. Nineteen patients had inoperable cancers. Three had gross recurrent cancer and three had measurable residual cancer after surgery. Three patients were treated post-operatively for microscopic residual disease. Seven different histological types of tumour were included. Six out of 8 patients with adenoid cystic carcinomas have lasting local tumour control. 54.5% of the gross tumours were locally controlled. All three of those classified as microscopic residual disease have no evidence of local recurrence. 11/14 cancers given 16.0 Gy or more in 20 fractions in 4 weeks were controlled compared with only 1/8 given a lower dose. 12/19 cancers less than 10.0 cm maximum diameter were controlled. The radiation-related morbidity was similar to that observed after photon therapy.

Fast neutron therapy for squamous cell carcinoma in the head and neck region: results of a randomized trial

A randomized trial of fast neuron therapy compared with 4MV photons for patients with head and neck cancer is reported. One hundred and sixty-eight patients were recruited between 1977 and 1984. The minimum follow-up is 2 years. Three patients were withdrawn before treatment began. Eighty-five were allocated to neutron therapy and 80 to receive photon therapy. All patients had squamous cell cancers in one of four primary sites: oral cavity, oropharynx, larynx, and hypopharynx. Local tumor control was similar in both groups: 44.7% after neutrons and 45.0% after photons. Salvage surgery was performed on 18 patients in each treatment group for residual or recurrent cancer. Acute radiation reactions of the mucous membranes were significantly more severe after photons. The number of patients with serious late reactions was greater after neutron therapy but the difference was not statistically significant. There were six deaths related to late morbidity after neutron therapy but none after photon therapy. Survival was better after photon therapy but the difference compared with the neutron group failed to reach statistical significance. When intercurrent deaths are excluded, the difference is less marked. Photon therapy was clearly better in terms of disease-free survival giving a 2-year local disease-free rate of 41.3% (s.e. 5.5%) compared with 29.4% (s.e. 4.9%) after neutrons.

Advances in pediatric radiotherapy in the last ten years and future proposals

Advances made can be divided into five main categories. Firstly, the problem of geographic miss which has been reduced by delivering effective radiation doses with greater precision. This has been accomplished with more sophisticated diagnostic and therapeutic equipment, immobilization techniques and computerized treatment planning. Second is the recognition of the interplay of radiation and chemotherapy on normal tissue tolerance and local tumor control. This interaction has necessitated reduction in both dose and volume of irradiation. Third is the use of wide field irradiation as a systemic treatment. Fourthly, the utilization of cooperative group trials to define the role of irradiation. Finally, with the improvement in survival has come the recognition of late effects of irradiation in the growing child and the means of reducing such effects. The current role of radiation therapy in childhood malignancies is summarized, controversies are identified, and future prospects explored.

Re-irradiation of advanced tumors of the head and neck with fast neutrons

Twenty-eight patients who had received radical treatment with X rays to tumors of the head and neck presented with advanced recurrent tumors, 23 of them had also undergone surgery and 10 had more than one operation. Seven had also received chemotherapy. They were treated with neutrons to a tumor dose of 1560 cGy in 12 fractions over 26 days using the techniques of the Hammersmith Unit. Twenty-three of the tumors (82%) underwent complete regression that was maintained in 15 for at least 12 months. Despite the damage done by the previous radiation and surgery to the normal tissues, 15 patients had no complications following neutron therapy. In six patients, there was major necrosis, in seven others, this was minor. Eight tumors recurred. Five patients responded with partial regression of their tumors. The median survival was 20 months (range 4-69 months).