Abstracts 329

of radiotherapy in the palliative setting, and the aim of this study was to assess whether response was related to dose.

A series of 12 patients with metastatic Ewing's sarcoma have been studied retrospectively. The mean time to development of metastases was 13.5 months: in five patients they were found at presentation. The commonest site irradiated was bone. A total of 38 courses of radiotherapy were administered.

Radiotherapy regimens were divided into three groups: >40 Gy, 20-40 Gy, and <20 Gy. Proportions of courses to which patients responded were 100%, 82.8%, and 76.9% respectively. Duration of pain free survival was found to be significantly longer in the higher dose groups.

These results infer that we should continue to use more traditional dose fractionation regimens in metastatic Ewing's sarcoma.

Localization in Radioimmunotherapy Using a Stereotactic Head Frame

R. Thomas, G. Flux and M. Brada, The Royal Marsden Hospital, Downs Road, Sutton, Surrey, UK

One prerequisite for studies using radioimmunotherapy (RIT) requires SPECT (Single Photon Emission Computed Tomo- graphy) images to be transposed on diagnostic CT images or diagnostic FDG-PET (18-fluorodeoxyglucose positron emission tomography). The SPECT scans demonstrate the patterns of radioisotope uptake and the CT scans depict the normal anatomy and turnout volume, with the FDG-PET scans providing addi- tional information on turnout volume.

To achieve this accurately, two critical steps have to be performed. First, all the images need to be reconstructed in the same spatial orientation. Secondly, these reconstructed images have to be integrated in three dimensions using a suitable computer assisted algorithm. Both these steps require fixed points visible on all scans which can act as the reference geometric co- ordinates, or fiducial points.

Integration of CT and FDG-PET images are possible using retrospective registration techniques, but as post-RIT SPECT scans do not show any traditional anatomical boundaries, meta- bolic landmarks or surface outlines, prospective techniques are required, such as a stereotactic head frame.

We report our technique of integration of CT/PET/SPECT scans for accurate assessment of radioisotope distribution using the Gill Thomas frame, the Brown-Roberts-Wells localization system and Analyse computer program in patients receiving intralesional 131I-labelled monoclonal antibody for recurrent high grade glioma.

Retreatment with Radiotherapy for Painful Bone Metastases

N. P. Mithal, P. R. Needham and P. J. Hoskin, Department of Radiotherapy and Oncology, The Royal London Hospital, Whitechapel, London E1 1BB, UK

External beam radiotherapy (EBRT) is widely used in the palliation of bone metastases, but little has been documented of retreatment response with EBRT in relapse.

105 patients treated with EBRT for painful bone metastases were reviewed (280 sites) of whom 31 had one or more sites retreated (57 retreated sites) and six patients (eight sites) received further irradiation to the same site.

Overall response rates of 84% and 87% were seen with first and second retreatments respectively.

Overall relapse rates were 25% for first treatment and 14% at second retreatment. Beam energy, patient gender, primary tumour histology and site irradiated did not influence retreatment response rates.

EBRT may be given as retreatment with reasonable palliation for bone metastases in those patients who have shown a previous response. Formal prospective clinical trials are recommended to determine optimum dose and fractionation schedules for individ- ual patients.

High Grade Thyroid Cancer Treated by Accelerated Radiotherapy

R. A. Huddart, P. Hoskin, P. Rhys-Evans and C. L. Harmer, Thyroid Unit, Royal Marsden Hospital, London SW3, UK

Anaplastic thyroid cancer frequently presents with advanced local disease with a median survival of a few months. Up to 75% of patients die from local progression despite conventional radio- therapy. Accelerated radiotherapy may be of value in such rapidly growing tumours.

Ten consecutive patients with advanced inoperable thyroid cancer (5 anaplastic, 2 poorly diffentiated medullary, 3 follicular) have been treated with a high dose accelerated regimen. Patients received 60.4 Gy in 32 fractions in 20-24 days, treating twice daily, five days a week.

Nine patients (90%) had an objective partial response, con- firmed by CT scan in seven. Four of these had complete clinical resolution of disease. Clinically significant symptom palliation occurred in eight. The non-responder had a minor response before dying of metastases with no local progression. After a median potential follow-up of 75 weeks (range 21-96) six patients have died, all of metastatic disease. The median survival was 24 weeks. All patients developed oesophagitis, with four needing opiate analgesia and five nasogastric feeding. One patient developed stridor due to laryngeal oedema and radiation pneumonitis.

The high response rate and good relief of local symptoms seen with accelerated radiotherapy requires further study although its use may be limited by toxicity.

Treatment of Oral Cancers Using Iridium-192 Interstitial Implants

T. J. Podd, P. K. D. J. Dawes and J. T. Roberts, Radiotherapy Department, Newcastle General Hospital, Westgate Road, Newcastle upon Tyne NE4 6BE, UK

The treatment options for early cancers of the oral cavity include radiotherapy and surgery.

This retrospective analysis of 74 cases documents the treatment results and morbidity of interstitial radioactive implants using 192Ir. The crude 5-year survival rates were 42% for T~, 33% for T2, and 0% for T3 tumours. Mortality from recurrent cancer was 28%, and from intercurrent disease 19%. The incidence of major radiation-induced morbidity was 11% and the local control rate was 81% for T1, 72% for T2, and 50% for T3 tumours.

Iridium wire brachytherapy is an effective method for the local control of small (T1 and Y2) oral cancers.

HDR Afterloading Therapy: Patient Acceptability and Side Effects

P. J. Hoskin, M. Cook and D. Bouscarle, Mount Vernon Centre for Cancer Treatment, Mount Vernon Hospital, Rickmansworth Road, Northwood, Middlesex, HA6 2RN, UK

In November 1992 a high dose rate remote afterloading facility (Gammamed) was introducted for routine gynaecological intra- cavitary treatments at Mount Vernon Hospital. All patients are seen routinely at 2 weeks following treatment and a standard questionnaire has been administered to assess the acceptability of this treatment and seek information on specific side effects. The results of the first 35 consecutive patients completing question- naires are presented.

Twenty-seven of 35 (77%) expressed a preference for the outpatient treatment but eight patients stated they would have preferred inpatient care; 32 patients (92%) reported they had received a satisfactory explanation of the procedure prior to treatment. Symptoms relating to the procedure were reported as follows: urinary frequency 21 (60%), pain 15 (43%), vaginal discharge ten (28%), diarrhoea nine (26%) and vaginal bleeding six (17%).

The final question related to embarrassment from the procedure which was reported by 20 patients (57%) but was rated mild in 14 of these and only severe in three.

In conclusion, patient satisfaction has generally been high from the introduction of outpatient high dose rate afterloading treat- ment. The high incidence of urinary frequency is probably related to catheterization prior to the procedure. Increased familiarity with three-channel applicators may improve techniques and reduce the incidence of severe pain associated with their use. Procedures for patient preparation and explanation were generally appreciated and successful.