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Biomedical subjects

A G Robertson

Publications and source records attributed to A G Robertson.

At least 55 records · Page 3Linked to original sources
PubMed1993

The effect of differing radiotherapeutic schedules on the response of glottic carcinoma of the larynx.

Laryngeal tumours, especially T1N0M0 and T2N0M0 lesions, are readily controlled by radiotherapy. Studies have shown that control varies with the dose of radiotherapy delivered to the tumour. Other factors, including the dose per fraction and the time over which the treatment schedule is delivered are also important. The varying biological effectiveness of a number of different dose fraction time schedules used in the management of laryngeal tumours of different stages are considered, the end points being tumour control and associated morbidity. Special attention has been given to the length of time over which the schedule is delivered. Of the schedules examined the results would suggest that a dose of 60 Gy given in 25 fractions over a period of 35 days is the best of the six schedules studied for T1, T2, T3 and T4 lesions with minimal associated morbidity. It is possible, however, that the poor results shown on the Kaplan-Meier curves for patients treated with the schedule of 60 Gy in 30 fractions over a period of 42 days could be due to geographical misses of the tumours as 56% were treated without a beam directed shell. The poor result obtained when patients were treated with the schedule of 60 Gy given in 30 fractions over 49+ days may be due to tumour repopulation occurring during the rest period though the possibility of geographical misses may contribute to the poor tumour control results. Mathematical modelling using linear quadratic analysis suggests that the shorter the period of time over which the treatment is given the better chance of achieving tumour control irrespective of the stage of the disease. These models were developed for patients treated with a beam directed shell thus excluding those patients who are most likely to be at risk from a geographic miss of the tumour. Linear quadratic analysis of the treatment data suggests that the ratio alpha/beta for tumour cells is estimated in the region of 13 Gy. For T1 lesions the tumour doubling time is in the order of 6 days, with longer doubling times for the more advanced stages. The analysis provides some support for investigative use of accelerated treatment schedules. This analysis also shows the importance of using beam directed shells when treating small fields especially in the head and neck region.

Adult↗
PubMed1993

A comparison of radiotherapy and surgery as primary treatment in the management of T3 N0 M0 glottic tumours.

Seventy-four patients with Stage T3 N0 M0 squamous carcinoma of the glottis were treated initially by either surgery or radiotherapy between 1980 and 1985. The treatment adopted was determined by consultant preference. The long-term survival in both groups was approximately the same. Of 38 patients treated initially by radiotherapy, 25 had local recurrence. Fifteen of these underwent salvage surgery and 10 died of disease. Thirteen patients (33 per cent) retained their larynx. One of the major advantages of treating patients with stage T3 N0 M0 carcinoma of larynx by radiotherapy initially is that approximately one-third will retain their larynx. Local recurrences can usually be treated readily by salvage surgery.

Aged↗
PubMed1993

Changes in the radiation treatment of cancer of the anus in Glasgow.

The survival and complication rate of two groups of patients with carcinoma of anus were compared. The first group of 20 patients were treated between 1974 and 1983 by double plane implantation using radium or equivalent caesium needles and supplementary external beam radiotherapy to groin nodes if present. The second group of 26 patients were treated between 1984 and 1990 by external beam radiotherapy followed by a jig implant using afterloading iridium needles. 5-year survival was superior in the second group (73% vs. 40%) with a lower incidence of radiation-induced complications.

Adenocarcinoma↗
PubMed1992

Identification of the histidine residue in Escherichia coli isocitrate lyase that reacts with diethylpyrocarbonate.

Escherichia coli isocitrate lyase was inactivated by diethylpyrocarbonate in a pseudo-first-order process. The enzyme was completely inactivated by modification of a single histidine residue, but slower modification of further residues also occurred. The substrate, isocitrate, and products, glyoxylate and succinate, protected against inactivation by diethylpyrocarbonate but this was not simply due to binding at the active site. Treatment of the inactivated enzyme with hydroxylamine led to only partial recovery of activity. Diethylpyrocarbonate also reacted with sulphydryl groups in isocitrate lyase, as judged by titrations with Nbs2, but this reaction was not responsible for the failure of hydroxylamine to reactivate the enzyme fully. The reactivity of isocitrate lyase to diethylpyrocarbonate declined with pH, following a titration curve for a group of pKa 6.1. Isolation and sequencing of ethoxyformylated peptides showed that the major site of modification by diethylpyrocarbonate was histidine residue 306.

Amino Acid Sequence↗
PubMed1992

An evaluation of functional outcome after surgery and radiotherapy for intraoral cancer.

Two hundred and fifty five patients undergoing treatment for oral cancer were studied. Tumour site, classification and treatment modality were recorded and an assessment of their ability to swallow was made postoperatively. Patients were graded into one of three groups depending on dietary consistency. Pre- and postoperative dental examinations were made and patients were weighted pre- and postoperatively. Postoperative functional problems are outlined. The results indicated that 21% of the sample reported difficulty with swallowing solid foods and 46% were limited to semi-solid or liquid diets postoperatively; 16% were unable to wear upper or lower dentures postoperatively and 15% of edentulous patients were able to wear an upper denture only; 65% of the patients who had surgery and radiotherapy were unable to regain their preoperative weight after 6 months. Patients with T1 tumours who did not progress to radiotherapy faired much better postoperatively and were more likely to return to normal diet and regain their preoperative weight.

Adult↗
PubMed1992

The management of tumours arising in the maxillary antrum.

Eighty-eight cases of tumours arising in the maxillary antrum undergoing treatment between 1967 and 1989 are reported. The series comprised 34 females and 54 males. Sixty-two patients had squamous cell carcinoma (SCC). Forty of those with SCC were treated by XRT only, four cases by surgery only, while the remaining 18 patients had surgery and post-operative XRT as a combined modality treatment. Early SCC (T2N0) was adequately controlled by radical radiotherapy alone with a 5-year survival of 69.1%. In more advanced SCC (T3N0 and (T4N0) radical radiotherapy alone was less successful with the 5-year survival falling to 19%. Combined modality treatment comprising radical surgery followed by radical postoperative radiotherapy improved 5-year survival in advanced SCC to 61%. It is therefore recommended that if patients are treated for cure, major surgery followed by radical postoperative radiotherapy is preferable in advanced squamous tumours ((T3/T4) of the maxillary antrum.

Adult↗
PubMed1992

Effect of radiation dose on the development of mixed haemopoietic chimerism following T cell-depleted allogeneic bone marrow transplantation.

The presence of mixed haemopoietic chimerism (MXC) was evaluated by cytogenetic and molecular analysis in 48 patients undergoing T cell-depleted BMT. The dose of total body irradiation (TBI) prescribed to all patients (14.4 Gy) was calculated to compensate for the absence of T cells in the graft. The actual midline dose of TBI received, however, differed significantly depending on the method of TBI administration. Thus, 35 adult patients received an average midline dose of 14.3 Gy, while 13 children received a lower dose of 13 Gy. The incidence of MXC in the adult group, who had received very close to 14.4 Gy to the midline, was 34% (12/35), which is lower than in most reported T cell-depleted series. During follow-up, chimerism remained relatively stable with time but varied between haemopoietic lineages. There was no relationship with relapse. MXC in the 13 children who had received a lower midline TBI dose was significantly higher at 69% (9/13) (p < 0.05) and increased to 90% (9/10) if patients who received additional chemotherapy in their conditioning were excluded (p = 0.001). This suggests that, in terms of marrow ablation, relatively small changes in the dose of TBI may be biologically significant, at least at this dose range. Again, in the lower TBI group MXC was not predictive of relapse.

Adolescent↗
PubMed1991

Subclinical pulmonary function defects following autologous and allogeneic bone marrow transplantation: relationship to total body irradiation and graft-versus-host disease.

Pulmonary function results pre- and post-transplant, to a maximum of 4 years, were analyzed in 98 patients with haematological disorders undergoing allogeneic (N = 53) or autologous bone marrow transplantation (N = 45) between 1982 and 1988. All received similar total body irradiation based regimens ranging from 9.5 Gy as a single fraction to 14.4 Gy fractionated. FEV1/FVC as a measure of airway obstruction showed little deterioration except in patients experiencing graft-versus-host disease in whom statistically significant obstructive ventilatory defects were evident by 6 months post-transplant (p less than 0.01). These defects appeared to be permanent. Restrictive ventilatory defects, as measured by reduction in TLC, and defects in diffusing capacity (DLCO and KCO) were also maximal at 6 months post-transplant (p less than 0.01). Both were related, at least in part, to the presence of GVHD (p less than 0.01) or use of single fraction TBI with absorbed lung dose of 8.0 Gy (p less than 0.05). Fractionated TBI resulted in less marked restricted ventilation and impaired gas exchange, which reverted to normal by 2 years, even when the lung dose was increased from 11.0 Gy to between 12.0 and 13.5 Gy. After exclusion of patients with GVHD (30% allografts) there was no significant difference in pulmonary function abnormalities between autograft and allograft recipients.

Adolescent↗
PubMed1990

Stomal recurrence: a separate entity?

Uncertainty exists concerning the exact aetiology of stomal recurrence following laryngectomy, although it is generally agreed that, when present, the prognosis is very poor. Fourteen cases of stomal recurrence were compared with 15 cases of other types of aggressive recurrence in the neck, for factors implicated in stomal recurrence. Similarities exist between the two groups and, although stomal recurrence has a greater association with subglottic tumour, this difference is not statistically significant. The possible mechanisms of recurrence are discussed, particularly in relation to aggressiveness, and it is concluded that factors involved in aggressive recurrences are similar. Stomal recurrence can be considered part of a group of aggressive neck recurrences associated with more advanced disease prior to laryngectomy.

Carcinoma, Squamous Cell↗
PubMed1990

Phase II trial of carboplatin and vinblastine in advanced squamous-cell carcinoma of the head and neck.

A chemotherapy regimen consisting of carboplatin and vinblastine was given to 30 patients with recurrent or previously untreated, locally advanced squamous carcinoma of the head and neck region. The main aim of the study was to assess the toxicity of this regimen, the feasibility of its outpatient administration and the tumour response. A total of ten patients (33%) achieved an objective response, including two who achieved a complete response. The combination offered useful palliation for patients with recurrent disease; it was well tolerated and can be given on an outpatient basis. This regimen could be combined with other active agents such as methotrexate or bleomycin.

Adult↗
PubMed1990

Assessment of factors influencing the outcome of radiotherapy for bladder cancer.

The results of treatment of 709 patients with carcinoma of the bladder are reported. Inclusion of the pelvic lymph nodes in the treatment volume failed to lead to any improvement in survival. The factors influencing survival were stage, tumour histology and differentiation. The presence of tumour at follow-up cystoscopy at 3 months was of great prognostic significance.

Aged↗
PubMed1989

Functional implications of major surgery for intraoral cancer.

A group of 41 patients were questioned about functional problems and concern for appearance, experienced following major surgery for intraoral malignancy. Twenty-five per cent of the group reported significant difficulties. Spouses reported a higher incidence of problems. The effects of primary tumour site and type of reconstruction on functional outcome are discussed.

Adenocarcinoma↗