Search PubMed⌕ Search

Biomedical subjects

R W Laing

Publications and source records attributed to R W Laing.

At least 19 recordsLinked to original sources
PubMed1997

Hypofractionated stereotactic radiotherapy in the management of recurrent glioma.

PURPOSE: This study aimed to assess the efficacy and toxicity of hypofractionated stereotactic radiotherapy (SRT) in the management of patients with recurrent glioma. METHODS AND MATERIALS: From January 1989 to July 1994, 36 patients with glioma were treated at the time of recurrence. Twenty-nine had recurrent high-grade astrocytoma, 3 high-grade oligodendroglioma, 1 high-grade ependymoma, and 3 pilocytic astrocytoma. Hypofractionated stereotactic radiotherapy was given using either three noncoplanar arcs or four to six noncoplanar fixed beams at 5 Gy/fraction, to doses ranging from 20 to 50 Gy initially on a dose escalation program. Two patients received 20 Gy, 8 received 30 Gy, 10 received 35 Gy, 10 received 40 Gy, 5 received 45 Gy, and 1 received 50 Gy, treating 5 days/week. RESULTS: The median survival of 29 patients with recurrent high-grade astrocytoma was 11 months from the time of SRT. This compared to a median survival of 7 months for a cohort matched for age, performance status, and initial histologic grade who received nitrosourea-based chemotherapy at recurrence (p < 0.05). Initial low-grade astrocytoma histology was the only favorable prognostic factor for survival on univariate analysis. Three patients with recurrent oligodendroglioma remain alive 11, 23, and 34 months after SRT. Three children treated for recurrent pilocytic astrocytoma remain alive 14, 41, and 55 months following SRT. Presumed radiation damage, defined as reversible steroid-dependent toxicity, was observed in 13 patients (36%) and required reoperation in 2 (6%). A total dose of >40 Gy was a major predictor of radiation damage (p < 0.005). CONCLUSION: Hypofractionated SRT is a noninvasive, well-tolerated, outpatient-based method of delivering palliative, high-dose, focal irradiation.

Adult↗
PubMed1994

Quality assurance in fractionated stereotactic radiotherapy.

The recent development of fractionated stereotactic radiotherapy (SRT), which utilises the relocatable Gill-Thomas-Cosman frame (GTC 'repeat localiser'), requires comprehensive quality assurance (QA). This paper focuses on those QA procedures particularly relevant to fractionated SRT treatments, and which have been derived from the technique used at the Royal Marsden Hospital. They primarily relate to the following: (i) GTC frame fitting, initially in the mould room, and then at each imaging session and treatment fraction; (ii) checking of the linear accelerator beam geometry and alignment lasers; and (iii) setting up of the patient for each fraction of treatment. The precision of the fractionated technique therefore depends on monitoring the GTC frame relocation at each fitting, checking the accuracy of the radiation isocentre of the treatment unit, its coincidence with the patient alignment lasers and the adjustments required to set the patient up accurately. The results of our quality control checks show that setting up to a mean radiation isocentre using precisely set-up alignment lasers can be achievable to within 1 mm accuracy. When this is combined with a mean GTC frame relocatability of 1 mm on the patient, a 2-mm allowance between the prescribed isodose surface and the defined target volume is a realistic safety margin for this technique.

Brain Neoplasms↗
PubMed1994

The significance of MALT histology in thyroid lymphoma: a review of patients from the BNLI and Royal Marsden Hospital.

Data from a series of 45 patients with Stage I and II non-Hodgkin's lymphoma (NHL) of the thyroid gland were analysed retrospectively to determine the incidence and prognostic significance of histopathological features of tumour origin from mucosa associated lymphoid tissue (MALT). The overall 5- and 10-year cause specific survival from NHL for the series was 79%. Evidence of tumour origin from MALT was the only significant prognostic factor for overall survival identified by multivariate analysis of the series (P < 0.01). A total of 31 (69%) tumours showed such evidence, the cause specific patient survival from NHL at 5 and 10 years being 90% compared with only 55% at 5 years for the 14 patients without such evidence. For patients given initial treatment with radiotherapy alone, those with evidence of tumour origin from MALT had a relatively low relapse rate and a relatively high success rate from salvage therapy, compared with a relatively high relapse rate and negligible success from salvage therapy in those without evidence of such tumour origin.

Adolescent↗
PubMed1994

Nodular basement membrane deposits in breast carcinoma and atypical ductal hyperplasia: mimics of collagenous spherulosis.

Collagenous spherulosis is characterised histologically by the accumulation of hyaline globules containing basement membrane components. Originally described in the breast, it has also been found in skin and salivary gland neoplasms. In the breast it has hitherto always been associated with benign disease and reports have asserted that this is invariably the case, cautioning against the diagnosis of malignancy when the condition is seen. We present here five cases with similar appearances to collagenous spherulosis in routine histology and immunohistochemistry, and ultrastructural studies in one of them, in which the condition was not associated with simple benign breast disease. Two of the cases were associated with invasive carcinomas of unusual histological types, one with intracystic papillary carcinoma, one with comedo ductal carcinoma-in-situ and one with atypical ductal hyperplasia. We suggest that appearances similar to collagenous spherulosis can be associated, either through being formed by a lesion or by collision, with malignancy and warn that on encountering the lesions the pathologist must not assume, as suggested in previous accounts, that it denotes a benign process. This is an important observation since collagenous spherulosis is likely to be encountered more frequently in the range of lesions biopsied in national breast screening programs.

Aged↗
PubMed1993

Efficacy and toxicity of fractionated stereotactic radiotherapy in the treatment of recurrent gliomas (phase I/II study).

Twenty-two patients with recurrent glioma have been treated on a dose escalation protocol with fractionated stereotactic external beam radiotherapy (SRT). All had previously received radical radiotherapy (median dose 55 Gy) as part of the initial treatment. The dose of SRT was increased from 30 Gy in six fractions to 50 Gy in ten fractions. Median survival from the date of SRT was 9.8 months. There was no significant acute morbidity but five patients who received > or = 40 Gy developed steroid responsive neurological deterioration assumed to represent late radiation damage. The survival and toxicity in patients with recurrent glioma are comparable with interstitial therapy. Fractionated SRT is a noninvasive form of localised radiation which may be a suitable alternative to interstitial therapy in this group of patients.

Adolescent↗
PubMed1993

Stereotactic radiotherapy of irregular targets: a comparison between static conformal beams and non-coplanar arcs.

Stereotactic radiotherapy using a linear accelerator is usually equated with the technique of delivery using multiple non-coplanar arcs, which achieves a spherical dose distribution. As the majority of intracranial lesions are not spherical, a range of schematized tumour shapes were planned to assess the role of static conformal beams in the treatment of irregular lesions. A sphere and 2 ellipsoids, ranging from 20 to 50 mm maximum diameter located intracranially were planned using 3, 4, and 6 non-coplanar static beams with conformal blocks and were compared with four 120 degree non-coplanar arcs. Comparison of the plans was made by the relative sparing of normal tissue outside the target volume using three-dimensional dose-volume distributions. Non-coplanar arcs spared more normal tissue at low isodoses and achieved the best high dose sparing for spherical targets. For the majority of irregular targets, 3 and 4 static beams spared more tissue at doses > or = 50% and > or = 80% than the arc technique. For all irregular volumes, maximum sparing of normal tissue to isodoses > or = 50% and > or = 80% of the treatment isodose was obtained with 6 static conformal beams. We conclude that irregularly shaped tumours suitable for stereotactic radiotherapy with a linear accelerator are better treated with conformal static non-coplanar beams rather than with the multiple arc technique.

Female↗
PubMed1993

Fractionated stereotactic external beam radiotherapy in the management of brain metastases.

24 patients with 28 brain metastases were treated with fractionated stereotactic radiotherapy (SRT). Doses ranged from 10 Gy in two fractions to 20 Gy in two fractions. 13 patients received SRT boost after whole brain radiotherapy (WBRT), 5 were treated with SRT alone and 6 were treated at the time of recurrence following WBRT. The median progression-free survival at the treated site was 18 months and the median survival was 18 months. All patients were treated without admission to hospital. Toxicity of fractionated SRT was minimal and patients treated without WBRT did not suffer significant alopecia. Fractionated SRT offers a non-toxic non-invasive alternative to excision surgery in patients with solitary brain metastases. The optimum fractionation schedule and the role of whole brain irradiation remain to be determined.

Adult↗
PubMed1993

Middle cerebral artery occlusion without craniectomy in rats. Which method works best?

BACKGROUND AND PURPOSE: Our purpose was to assess the effectiveness of middle cerebral artery occlusion in producing acute focal ischemia in the rat by the use of Koizumi's and Longa's methods, in which occlusion is achieved by passing a nylon thread into the internal carotid artery. METHODS: Cerebral blood flow was measured by using the hydrogen clearance method, and the brains were examined histologically to assess ischemic damage. RESULTS: By Koizumi's method profound reduction in cerebral blood flow was achieved in 28 of 30 rats (93%). The mean cerebral blood flow in the middle cerebral artery territory was 10.7 (95% confidence interval, 9.9-11.5) ml/100 g per minute. By Longa's method reduction in cerebral blood flow was achieved in only 29 of 52 rats (56%), and in these animals mean cerebral blood flow was 33 (95% confidence interval, 28.3-33.7) ml/100 g per minute (p < 0.001 compared with Koizumi's method). Cerebral blood flow was reduced to < 16 ml/100 g per minute in only seven animals (24%). CONCLUSIONS: By Koizumi's method the depth of ischemia is more profound, occlusion is achieved in a much higher proportion of cases, and the incidence of perforation of the intracranial internal carotid is much less frequent than by Longa's method.

Acute Disease↗
PubMed1993

Feasibility of patient immobilization for conventional cranial irradiation with a relocatable stereotactic frame.

The precision of patient repositioning and the firmness of immobilization are among the major determinants of the accuracy of radiation treatment delivery. A relocatable Gill-Thomas localizer (GTL) developed for neurosurgery and stereotactic radiotherapy achieves highly accurate relocation and immobilization and has been used successfully for fractionated stereotactic radiotherapy of intracranial lesions. The feasibility of using GTL for immobilization in conventional fractionated external beam radiotherapy was assessed by comparison with conventional Cabulite shell head fixation. The GTL was well tolerated at the time of preparation and during a 5 week course of radiotherapy. The principal advantage was superior relocation accuracy maintained throughout the course of treatment, high precision of field set-up and markedly reduced production time. In addition the time taken to position the patient in the treatment room was also marginally shortened. GTL is therefore a feasible method of head fixation for conventional cranial irradiation providing patients have adequate dentition. With further development the relocatable method of immobilization originally designed for stereotactic radiotherapy may become the preferred technique particularly in situations where high accuracy is desirable, such as stereotactically guided conformal radiotherapy.

Adenoma↗
PubMed1992

Intracranial germ cell tumour in association with cryptorchidism.

An intracranial germ cell tumour (GCT) in a patient with cryptorchidism is presented. The known association between testicular GCTs and cryptorchidism suggests a possible common predisposition for gonadal and extragonadal tumours. To confirm this the frequency of the reported association needs to be defined.

Adolescent↗
PubMed1992

A case of lung carcinoma induced by radioactive iodine given for disseminated thyroid carcinoma.

We report a case of a patient who at the age of 32 developed a squamous carcinoma arising in the thorax. At 7 years of age he had received aggressive treatment with 131I for a thyroid carcinoma with multiple pulmonary metastases. Radiation induced malignancy, in sites such as the bone marrow or bladder, after 131I therapy is recognized; however, tumours arising in the thorax after such treatment have not been described.

Adult↗
PubMed1992

Acute bilateral ballism in a patient with intravascular dissemination of gastric carcinoma.

An 84-year-old woman presented with an acute onset of violent bilateral ballism-chorea. She was admitted to the local neurology unit, but not definite diagnosis could be made of the underlying condition, although she did appear to have bronchopneumonia. At autopsy the stomach wall was thickened, and the lesser curve lymph nodes were firm and enlarged. A single nodule was noted in the liver while the lungs appeared consolidated. Histology revealed a moderate-to-poorly differentiated gastric adenocarcinoma with extensive intravascular dissemination which included the central nervous system (CNS). Numerous small infarcts related to vessels occluded by tumour were present throughout the brain, and we feel that this was the underlying mechanism for the acute onset of ballism.

Adenocarcinoma↗
PubMed1992

Thorotrast granuloma: an unexpected diagnosis.

An example of a Thorotrast granuloma (thorotrastoma) occurred in the neck of a patient 44 years after a carotid angiogram in which Thorotrast was used as radiological contrast medium. The lesion had produced a "cold" abscess and the patient was undergoing treatment for retropharyngeal tuberculosis. Thorotrast leakage can produce unusual clinical symptoms and signs which are frequently misdiagnosed.

Aged↗
PubMed1992

Failure of conventionally fractionated radiotherapy to decrease the risk of hemorrhage in inoperable arteriovenous malformations.

Twenty-six patients with arteriovenous malformations (AVMs) were treated between 1965 and 1986 with conventional fractionated radiotherapy at the Royal Marsden Hospital. There were 14 male patients and 12 female, aged 11 to 57 years (median, 24 yr). Twenty-five patients completed radiotherapy with a localized treatment target volume of a dose of 40 to 54 Gy. The median follow-up was 14.5 years. Eleven patients had an additional hemorrhage. The actuarial annual risk of bleeding was 2.3%, which is similar to that found in untreated patients. Follow-up angiograms were performed in 11 patients, and 10 showed persistence of AVM. The results suggest that fractionated radiotherapy in conventional doses does not make a large impact on the risk of hemorrhage in patients with inoperable AVMs, and, where possible, stereotactic external beam radiotherapy/radiosurgery should be employed.

Actuarial Analysis↗