Fast neutrons in the treatment of head and neck cancers: the results of a multi-centre randomly controlled trial

Interventions for the treatment of oral cavity and oropharyngeal cancer: radiotherapy

BACKGROUND

The management of advanced oral cavity and oropharyngeal cancers is problematic and has traditionally relied on surgery and radiotherapy, both of which are associated with substantial adverse effects. Radiotherapy has been in use since the 1950s and has traditionally been given as single daily doses. This method of dividing up the total dose, or fractionation, has been modified over the years and a variety of approaches have been developed with the aim of improving survival whilst maintaining acceptable toxicity.

OBJECTIVES

To determine which radiotherapy regimens for oral cavity and oropharyngeal cancers result in increased overall survival, disease free survival, progression free survival and locoregional control.

SEARCH STRATEGY

The following electronic databases were searched: the Cochrane Oral Health Group's Trials Register (to 28 July 2010), CENTRAL (The Cochrane Library 2010, Issue 3), MEDLINE via OVID (1950 to 28 July 2010) and EMBASE via OVID (1980 to 28 July 2010). There were no restrictions regarding language or date of publication.

SELECTION CRITERIA

Randomised controlled trials where more than 50% of participants had primary tumours of the oral cavity or oropharynx, and which compared two or more radiotherapy regimens, radiotherapy versus other treatment modality, or the addition of radiotherapy to other treatment modalities.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of risk of bias was undertaken independently by two or more authors. Study authors were contacted for additional information as required. Adverse events data were collected from published trials.

MAIN RESULTS

30 trials involving 6535 participants were included. Seventeen trials compared some form of altered fractionation (hyperfractionation/accelerated) radiotherapy with conventional radiotherapy; three trials compared different altered fractionation regimens; one trial compared timing of radiotherapy, five trials evaluated neutron therapy and four trials evaluated the addition of pre-operative radiotherapy. Pooling trials of any altered fractionation radiotherapy compared to a conventional schedule showed a statistically significant reduction in total mortality (hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.76 to 0.98). In addition, a statistically significant difference in favour of the altered fractionation was shown for the outcome of locoregional control (HR 0.79, 95% CI 0.70 to 0.89). No statistically significant difference was shown for disease free survival.No statistically significant difference was shown for any other comparison.

AUTHORS' CONCLUSIONS

Altered fractionation radiotherapy is associated with an improvement in overall survival and locoregional control in patients with oral cavity and oropharyngeal cancers. More accurate methods of reporting adverse events are needed in order to truly assess the clinical performance of different radiotherapy regimens.

The Inherent Cellular Sensitivity to 62·5 MeV(p→Be+)Neutrons of Human Cells Differing in Photon Sensitivity

The inherent sensitivity of 20 human cell lines to the 62.5 MeV(p----Be+) clinical neutron beam at Clatterbridge, UK, has been assessed and compared to their sensitivity to 4 MeV photons. The survival curves of the cell lines following neutron irradiation were curvilinear, and the inherent neutron sensitivity varied by 4.5 fold (0.1 survival level) between the extreme values, in the cell lines studied. There was a strong correlation between the sensitivity of these human cells to photon and neutron irradiation. It was concluded that should these in vitro patterns occur in the clinic, the 4-fold variation in RBE and inherent sensitivity to neutrons could result in overall lower local control rates following fast neutron therapy than might be anticipated. It suggests the need for the development of predictive assays as a potential means of selecting tumours most appropriate for neutron therapy.

Le traitement par neutrons : hadronthérapie partie II : bases physiques et expérience clinique

Neutrons have radiobiological characteristics, which differ from those of conventional radiotherapy beams (photons) and which offer a theoretical advantage over photons to fight radioresistance by the differential relative biological effect of them between normal and tumour tissues. Neutron therapy beneficed of great interest between 1975 and 1985. Many of phase III trials were conducted and indications have been definitively deducted of them. After briefly describing the properties of neutron beams, this review discusses the indication of neutron therapy on the basis of the clinical results. Salivary, prostate tumours and sarcomas are the main indications of neutron therapy. In concern to the prostate cancers, other alternative treatments reduce the neutron therapy field. For sarcomas, the lack of randomised trials limits the impact of the interest of neutrons. For other tumours, the ratio benefice/risk of neutron therapy is inferior to these obtained with photons and they could not be considered like classical indications.

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.

The role of fast neutrons in the treatment of squamous cell carcinomas of the head and neck: The European experience

After the first European stet on neutron therapy of head and neck cancer, published by Catterall and Bewley, revealed significant advantages of neutrons over photons in 134 randomized patients, the subsequent phase II and phase III studies led to controversial results. Figures for local tumor control varied from 26-76% after 2 years to 19% after 10 years and for survival from 16-46% after 2 years to 14% after 10 years. Results of all studies were consistent with showing an increased incidence of severe late effects. Eligibility criteria with regard to the tumor stage, history, and previous therapies of relapses varied from study to study. Also, physical treatment parameters, such as neutron energy, LET and OER, neutron and photon doses for one fraction and for the total radiotherapy were rather different. The benefit of neutron therapy in comparison with photons was low or non-existent when smaller tumor stages, such as primaries T2 or lymph nodes N1 were included into the trial. It increased when only T4 tumors, recurrences or tumors persisting after conventional radiotherapy were treated and when the percentage of fixed lymph nodes increased. There was only one European study in which patients suffering form lymph node metastases of the neck had, in contrast to American data (Griffin et al. 1978), a worse prognosis after neutrons than after photon therapy (Duncan et al. 1987b). In our own phase II study on reactor neutron therapy of 100 patients suffering from relapses and persistent tumors, not yet published, 3-year survival of 21% and 3-year local control of 32% were obtained. Although this was not a randomized study, during this period all patients with equivalent tumors treated by photon therapy alone died within 2 years. In conclusion there is no general indication for neutron therapy in squamous cell carcinoma of the head and neck, but there is a benefit of neutrons in palliative treatment of recurrences, necrotic and hypoxic primaries and lymph nodes.

Particle beam therapy (hadrontherapy): basis for interest and clinical experience

The particle or hadron beams deployed in radiotherapy (protons, neutrons and helium, carbon, oxygen and neon ions) have physical and radiobiological characteristics which differ from those of conventional radiotherapy beams (photons) and which offer a number of theoretical advantages over conventional radiotherapy. After briefly describing the properties of hadron beams in comparison to photons, this review discusses the indications for hadrontherapy and analyses accumulated experience on the use of this modality to treat mainly neoplastic lesions, as published by the relatively few hadrontherapy centres operating around the world. The analysis indicates that for selected patients and tumours (particularly uveal melanomas and base of skull/spinal chordomas and chondrosarcomas), hadrontherapy produces greater disease-free survival. The advantages of hadrontherapy are most promisingly realised when used in conjunction with modern patient positioning, radiation delivery and focusing techniques (e.g. on-line imaging, three-dimensional conformal radiotherapy) developed to improve the efficacy of photon therapy. Although the construction and running costs of hadrontherapy units are considerably greater than those of conventional facilities, a comprehensive analysis that considers all the costs, particularly those resulting from the failure of less effective conventional radiotherapy, might indicate that hadrontherapy could be cost effective. In conclusion, the growing interest in this form of treatment seems to be fully justified by the results obtained to date, although more efficacy and dosing studies are required.

The treatment of recurrence following fast neutron therapy for head and neck malignancy

Twenty-eight patients received fast neutron therapy for head and neck malignancy. Of these, seven had no recurrence, 13 had a recurrence at the primary site, five had a recurrence in the neck and three had a recurrence in the neck and at the primary site. Treatment of a primary site recurrence was difficult with seven of the eight patients submitted for major surgical resection developing serious complications. Of the six patients developing a fistula four required flap repair. The tumour specific 5-year survival for the whole group of 28 patients was 29%. The surgical treatment of locoregional recurrence following fast neutron therapy is fraught with problems and some type of flap repair is usually necessary.

Clinical trials of neutron radiotherapy in the United States

The development of clinical neutron facilities in the 1980s, capable of delivering high energy neutrons spurred full scale phase III testing of neutron beam radiotherapy in a number of tumors including salivary gland, head and neck, prostate, and non small-cell lung cancer. The Radiation Therapy Oncology Group (RTOG) and the Medical Research Council (MRC) jointly sponsored a randomized trial for the treatment of advanced stage salivary gland tumors comparing neutron to conventional photon and/or electron radiotherapy. Although no improvement in survival was seen, the study demonstrated a striking and statistically significant difference in the local-regional control of unresectable salivary gland tumors (56 vs 17%), favoring neutron beam irradiation. Subsequent clinical trials of neutron beam irradiation were initiated by the Neutron Therapy Collaborative Working Group (NTCWG) sponsored by the National Cancer Institute (NCI). A phase III trial comparing neutron to photon radiotherapy for inoperable regional non-small cell lung cancer showed no overall improvement in survival. However, a statistically significant improvement in survival was observed in the subset of patients with squamous cell histology. The NTCWG trial comparing fast-neutron therapy versus conventional photon irradiation in the treatment of advanced squamous cell carcinomas of the head and neck showed a statistically significant improvement in initial complete response (70 vs 52%) favoring neutrons. However, subsequent failures erased any difference in ultimate local-regional control rates and survival curves were essentially the same in both arms. The randomized study of the NTCWG for locally advanced prostate cancer demonstrated a significant decrease in local-regional failure (11 vs 32%) at 5 years, favoring the neutron arm. Furthermore, biochemical measures of disease control also favored the neutron arm with prostate specific antigen (PSA) levels elevated in 17% of the neutron-treated patients compared to 45% of the photon-treated patients at 5 years. At the 5-year analysis, no significant difference in survival was observed between the two arms; however, longer follow-up is necessary to assess the ultimate impact of improved local-regional control on survival. An analysis of complications in this series revealed the importance of beam shaping and treatment planning capabilities in maintaining long-term sequelae following neutron irradiation at an acceptably low level.

The Saudi experience with neutron therapy in locally advanced head and neck cancers

The neutron therapy program at King Faisal Specialist Hospital and Research Center conducted a phase II study to evaluate the toxicity and efficacy of neutrons against conventional external megavoltage irradiation in patients with locally advanced head and neck malignancy. One hundred and nineteen patients were allocated to receive either photons (46/119) or neutrons (73/119). Radiation effects were scored according to the EORTC/RTOG criteria; data was collected weekly during treatment, once a month for the first year and at 6-month intervals subsequently. While acute effects were scored in all patients, only 59 were evaluable for late effects and locoregional control. A composite of the average reaction results were obtained using this information, to compare them in time, for acute and late effects in both arms of the study. The maximum acute reactions in the two groups were similar. In the majority of the patients (80%) acute skin and mucosal reactions occurred during the last week of treatment. The changes in the subcutaneous tissues and salivary glands became clinically apparent at 3 months or later. Salivary gland toxicity was more severe in the photon arm and the difference was statistically significant at 3 months (P = 0.04) but this was lost at 12 months. Late effects for skin and subcutaneous tissues were significantly more severe in the neutron arm with P values of 0.04 and 0.01 respectively. Three patients in the neutron arm died of grade 4 radiation complications. The local control and survival were similar in both groups.

Fast-neutron therapy in advanced head and neck cancer: a collaborative international randomized trial

PURPOSE

To compare the efficacy of fast-neutron radiotherapy with that of conventionally fractionated photon therapy in the management of patients with locally advanced squamous cell carcinoma of the head and neck.

METHODS AND MATERIALS

Patients with Stage III or IV disease were randomized to receive either 20.4 Gy/12 fractions/4 weeks of neutrons or 70 Gy/35 fractions/7 weeks of photons (control). Between April 1986 and March 1991, 178 patients were entered, 169 of whom were eligible for analysis. The treatment arms were balanced for age, stage, and performance status, but not for primary site of origin.

RESULTS

Complete response occurred in 70 and 52% with neutrons and photons, respectively (p = 0.006). Local regional failure at 3 years for all patients was 63% for neutrons and 68% for photons. Actuarial overall survival curves were virtually identical in both study arms, falling to 27% at 3 years. Acute toxicity was similar in the two arms, but late grade 3-5 toxicity was 40% with neutrons compared to 18% with photons (p = 0.008).

CONCLUSION

Although the initial response rate was higher with neutrons, permanent local control and survival were not improved, and the incidence of late normal tissue toxicity was increased. As a result, fast-neutron therapy for advanced squamous cell carcinoma of the head and neck can only be recommended for patients in whom the logistic benefit of treatment in 12 sessions over 4 weeks outweighs the increased risk of late toxicity.

Ultrastructural changes in the cochlea of the guinea pig after fast neutron irradiation

Guinea pigs were irradiated with fast neutrons. After a single dose of 2, 6, 10, or 15 Gy was applied, scanning and transmission electron microscopy of the temporal bone was performed to assess the effect of fast neutron irradiation on the cochlea. Outer hair cell damage appeared with neutron irradiation of more than 10 Gy, and inner hair cell damage with neutron irradiation of more than 15 Gy. Outer hair cells were more severely damaged than inner hair cells. No statistically significant differences were found in damage of basal, middle, and apical turns. The second and third rows of outer hair cells were more severely damaged than the first row of outer hair cells. The most significant findings in transmission electron microscopy were clumping of chromatin and extension of the heterochromatin in the nuclei of hair cells. The cytoplasmic changes were sequestration of cytoplasm, various changes of mitochondria, formation of vacuoles, and irregularly arranged stereocilia. The morphologic change in stria vascularis was intercellular and perivascular fluid accumulation. It appeared to be a reversible process.

Development of fast neutron therapy worldwide. Radiobiological, clinical and technical aspects

Radiobiological data indicate that fast neutrons could bring a benefit in the treatment of some tumour types, and suggest mechanisms through which this benefit could be achieved. However, radiobiology also clearly indicates that there is a need for patient selection as well as for a high-physical selectivity. The main difficulty when interpreting the results of neutron therapy are the poor technical conditions in which the first treatments were applied. This explains why the value and the place of neutron therapy are not universally recognized, although more than 15,000 patients have been treated so far worldwide. There are, however, clinical indications of fast neutrons bringing a benefit for the following tumour sites: salivary glands, paranasal sinuses, soft tissue sarcomas, prostatic adenocarcinomas, palliative treatment of melanoma and rectum. These tumours represent about 10-15% of all patients currently referred to the radiation therapy departments.

Fast neutron radiation therapy. Results of phase III randomized trials in head and neck, lung, and prostate cancers

The results of phase III trials comparing neutrons to photons for head and neck squamous cell cancers, non-small cell lung cancers, and prostate adenocarcinomas are reviewed, with emphasis given to the most recent U.S. National Cancer Institute sponsored randomized clinical studies in which fast neutrons were delivered using modern, hospital-based, high-energy, isocentric-capable cyclotrons. In locally advanced squamous cell head and neck cancers, neutrons showed no convincing advantage over photons. Fast neutron radiotherapy may have provided a therapeutic benefit in selected patients with inoperable non-small cell lung cancers. For locally advanced prostate adenocarcinomas, neutron therapy resulted in significantly superior clinical and histological loco-regional tumor control, which may translate to improved survival with additional follow-up. In general, severe late complications were more frequent with neutrons, especially in patients treated on older physics laboratory-based equipment. Even with modern state-of-the-art neutron generators, careful beam collimation and treatment planning are required to minimize side effects.

Complications following fast neutron therapy for head and neck cancer

Serious complications resulting from the use of fast neutrons to treat head and neck malignancies are reported in 38 patients. The average interval between treatment and onset of complications was 5.5 years. Significant airways obstruction, requiring a tracheostomy, occurred in two patients, and a gastrostomy or pharyngostomy was performed for intractable dysphagia in six. Eight patients developed osteoradionecrosis: carotid artery rupture occurred in three patients following surgery for residual or recurrent disease. Our experience suggests that complications following fast neutron therapy for head and neck tumours are more severe, more common and occur after a longer time interval than those seen following conventional radiotherapy. Subsequent surgery in the irradiated area is compromised by severely impaired wound healing. When radical surgery is necessary for residual or recurrent disease the entire volume of irradiated tissue must be removed if healing is to be achieved.

Preclinical studies with the Faure high energy neutron facility: response of pig skin to fractionated doses of fast neutrons (66 MeVp----Be)

The early and late responses of pig skin to fractionated doses of both unfiltered and filtered (i.e. hardened) neutrons using the Faure neutron therapy facility (66 MeVp----Be) were determined and compared with those following fractionated doses with 60Co gamma-rays. Dose-effect curves for the quantal responses of moist desquamation (early epithelial response) and dermal necrosis (late response) were fitted by probit analysis and ED50 values obtained. For a neutron fractionation scheme comprised of 12 fractions in 26 days, and using an unfiltered beam, the ED50 values for moist desquamation and dermal necrosis were 18.67 +/- 2.22 and 22.25 +/- 0.48 Gy, respectively, whereas in the case of the filtered beam, the corresponding ED50 values were 24.78 +/- 1.44 and 23.30 +/- 0.47 Gy. In order to provide a comparison, the values for 24 fractions of 60Co gamma-rays given in 39 days (a clinical protocol used in the Groote Schuur Hospital) were 74.02 +/- 2.92 and 66.72 +/- 1.93 Gy for moist desquamation and dermal necrosis, respectively. For the unfiltered beam, values for the comparative biological effectiveness (CBE) were 3.96 and 3.00 for the early and late skin response, respectively. The corresponding CBE values were for the filtered beam 2.99 and 2.86. These results for the Faure neutron therapy facility can be extrapolated to the human situation with a high degree of confidence, so that the neutron dose which would yield acceptable skin damage in patients may be determined using the data presented here.

Review of the clinical results of fast neutron therapy

The clinical results reported from the different neutron therapy centres are reviewed. Fast neutrons were shown to be useful in the treatment of locally extended inoperable salivary gland tumours (average local control rates 67% for neutrons compared to 28% for photons). For paranasal sinuses and some tumours of the head and neck area, especially extended tumours with large fixed lymph nodes, neutrons could also be of interest. By contrast, the results obtained for brain tumours were, in general, disappointing. Neutrons were shown to be beneficial in the treatment of well differentiated soft tissue sarcomas, as well as to bone- and chondrosarcomas. For locally extended prostatic adenocarcinoma, a RTOG randomized trial gave local control rates of 77% for mixed schedule compared to 31% for photons. Neutrons could be useful also for palliative treatment of melanomas. Further studies are needed in order to evaluate the benefit of fast neutrons for other localizations such as uterine cervix, bladder and rectum. It can be concluded that fast neutrons could be of interest for about 10% of the radiotherapy patients, but it is likely that the new high-energy hospital-based cyclotrons will further extend the indications of neutron therapy. However, patient selection remains one of the main problems and there is a need for development of individual predictive tests.

The relative biological effectiveness of fractionated doses of fast neutrons (42 MeVd----Be) for normal tissues in the pig. I. Effects on the epidermis and dermal vascular/connective tissues

The effects of fractionated doses of fast neutrons (42 MeVd----Be) on the early epithelial and later dermal response of pig skin have been assessed and compared with those after X irradiation. For the early epithelial reaction, i.e. moist desquamation, the relative biological effectiveness (RBE) of the neutron beam increased with the decreasing size of the X-ray dose/fraction. There was an experimentally observed upper RBE value of approximately 2.75 for X-ray doses/fraction of between 2 and 5 Gy. For the late reaction of ischaemic dermal necrosis the RBE was greater than 3.0 for X-ray doses/fraction of less than 3 Gy and, based on the assumptions made in the linearquadratic model of cell survival, an upper limiting RBE of 4.32 +/- 0.39 was calculated for infinitely small doses/fraction. These findings were compared with other radiobiological data and the conclusions drawn from the results of clinical trials. It was concluded that for the sparing of late effects in skin and subcutaneous tissues, relative to acute reactions, a relatively small number of fractions in a short overall treatment time may be optimal for fast neutron therapy.

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.

A d(16) + Be fast neutron beam for therapy

A fast neutron therapy facility has been established utilizing the classical solid-pole cyclotron of the National Accelerator Centre (CSIR) in Pretoria. The neutron field is generated from the 9Be(d,n)10B reaction using 16 MeV deuterons on a thick target, yielding 0.51 cGy.min-1.microA-1 at an SSD of 135 cm. Essentially the beam characteristics concur with those measured at other centres with comparable energies.

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.

The Amsterdam fast neutron therapy project: a final report

In the period from February 1975 through September 1981 a total of 435 patients received radiotherapy with the 14 MeV d + T neutron generator, hospital based in the Netherlands Cancer Institute (the Antoni van Leeuwenhoek Hospital). Preliminary data on clinical results were published during the past few years. In this paper a final report is given of the program. The results can be summarized as follows: The neutron generator fulfilled the criteria for clinical use, that is it was reliable and had the required minimal output of 10(12) neutrons s-1. However, the dose distribution was more comparable with a 250 kV X-ray machine than with a modern accelerator. A number of physical parameters of importance for clinical neutron dosimetry have been determined for our therapy unit. These data, as well as the results of dosimetry intercomparisons in which our institute participated, contributed in the drafting of a European protocol for clinical neutron dosimetry. Pilot studies were carried out on different tumor sites, including head and neck, brain, pelvis, soft tissue and pulmonary metastases. In many patients local tumor control was seen, however, often concomitant with severe complications, especially in deep seated tumors. Randomized clinical trials were carried out for head and neck tumors (in collaboration with some other European centers) and for inoperable bladder and rectal tumors. No significant difference was observed in local tumor control or late morbidity between photon and neutron irradiation for the head and neck tumors. Also the results for pelvic tumors failed to demonstrate an advantage for neutron therapy. In this study two neutron arms were used with different dose schedules. As could be expected a higher local control rate was noticed for the higher neutron dose group, but concomitant with a higher complication rate. From our experience we have to conclude that treatment with our fast neutron treatment facility did not result in a benefit over photon irradiation. It seemed that the differential effect between tumor and normal tissues is smaller with fast neutrons than with photons.

Regional outcome in oropharyngeal and pharyngolaryngeal cancer treated with high dose per fraction radiotherapy. Analysis of neck disease response in 1646 cases

Out of a series of 1666 consecutive patients with squamous cell carcinoma of oropharynx and pharyngolarynx, 1646 were evaluable at a 3-year interval following radical radiation therapy. The actuarial 3-year nodal control rate using the AJC classification was: N0 98%, N1 90%, N2 88%, N3 71% when the primary was controlled. The regional outcome is influenced by clinical features such as nodal size, multiplicity and fixity. Cervical recurrence frequency is higher for pharyngolaryngeal carcinoma than for oropharyngeal cancer. The impact of the treatment planning on regional control is discussed. Due to the of concomitant boosting of nodes, cervical metastases were treated according to a type of accelerated fractionation schedule with weekly doses of 12-15 Gy for a total of 70-85 Gy in 75% of the cases. Clear-cut dose control relationships are demonstrated for nodes larger than 3 cm in diameter. Overboosting residual cervical disease fails to yield a better nodal control. Comparative analysis is established between results obtained with this high dose per fraction radiotherapy schedule, conventional regimens of irradiation and other new approaches, combining chemical and physical agents. Therapeutic implications are also derived to define adequate field coverage.

A comparative review of the Hammersmith (1971-75) and Edinburgh (1977-82) neutron therapy trials of certain cancers of the oral cavity, oropharynx, larynx and hypopharynx. Medical Research Council Neutron Therapy Working Group

Because of apparent inconsistencies in the two trials of neutron therapy carried out under its auspices, the MRC in 1982 requested a comparative review of the data in the Hammersmith and Edinburgh trials in so far as the clinical material allowed of such comparison. It was clear that the two trials were not only not contemporaneous (Hammersmith 1971-75; Edinburgh 1977-82) but that they differed in site and stage of disease as well as in the parameters of radiation dosage. Only a fraction of the patients were comparable and this review, which sets out the differences in design and conduct of the two trials, focuses on squamous-cell carcinoma in the four sites--oral cavity, oropharynx, larynx and hypopharynx--which were common in both. The first 120 patients entered into the Edinburgh trial have been compared with the 95 patients selected from 161 in the Hammersmith trial who would have been eligible at Edinburgh by reason of the site of disease and histology. Thus, Hammersmith patients with tumours of salivary glands, sinuses and neck nodes were, of necessity, excluded. Within such limitations the data on case distribution, tumour size and stage, the parameters of radiation dosage and the outcome in terms of tumour control, survival and treatment morbidity have been subjected to rigorous assessment and analysis. The important aspects in which the two investigations had differed included the stage of disease (more advanced at Hammersmith, with 63% of patients having fixed nodes, compared with 27% at Edinburgh); radiation dosage (the median neutron dose being 5% lower at Edinburgh than at Hammersmith while the median photon dose was l0% higher at Edinburgh); the "photon arm" of the Edinburgh trial being on site whereas that at Hammersmith had been at multiple centres; and the years in which the trials had been carried out. The two series are comparable in terms of treatment failure (local recurrence or late radiation death) following local tumour control. The results are also consistent in associating an increased incidence of late severe radiation morbidity and of intercurrent deaths with neutron therapy. In three other respects the results of the two series differ. At Edinburgh there was advantage to the photon-treated patients in terms of overall mortality, whereas at Hammersmith the advantage was to those treated with neutrons. The incidence of tumour regression for patients randomised to photons was much lower in the Hammersmith trial than for neutrons, whereas in Edinburgh the two modalities gave similar results.