Search PubMed⌕ Search

Biomedical subjects

M Back

Publications and source records attributed to M Back.

At least 19 recordsLinked to original sources
PubMed2005

Absence of adverse early quality of life outcomes of radiation therapy in breast conservation therapy for early breast cancer.

The New South Wales Breast Radiation Oncology Group has completed a prospective multicentre study of the impact of radiation therapy (RT) on acute toxicity and quality of life (QoL) in women with early breast cancer treated with breast conservation therapy. The patient group received adjuvant breast tangential RT after wide local excision of breast cancer. Acute toxicity and cosmesis was assessed quantitatively and qualitatively. European Organization of Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-30) and Perceived Adjustment to Chronic Illness Scale (PACIS) were the QoL instruments used. Of 175 women, 34.3% described lethargy leading to a significant disruption to normal activity during RT. At week 6, this had reduced to 7.5% reporting significant lethargy. No negative effects on QoL were noted over the time period of RT; EORTC demonstrated no difference (P = 0.79). PACIS recorded a significant improvement in functioning (P < 0.001) from baseline to week 6. Univariate analysis on potential predictive patient, tumour and treatment factors demonstrated an association of baseline pre-RT breast discomfort with worse lethargy (P = 0.03), EORTC (P < 0.01) and PACIS (P < 0.01) measures. This study confirms the minimal impact of RT on patient functioning at 6 weeks post-treatment.

Adult↗
PubMed2005

Importance of radiation time and dose factors on outcome for childhood medulloblastoma.

The purpose of this study was to investigate the relationship of posterior fossa radiation therapy duration (PFRTD) and relapse-free survival (RFS) following adjuvant craniospinal RT for childhood medulloblastoma. A retrospective audit was performed assessing all children aged <18 years managed with adjuvant craniospinal RT for medulloblastoma in Australia and New Zealand in 1980-1993. Children receiving prolonged (>180 days) pre-RT chemotherapy were excluded. Data were obtained for potential prognostic factors in domains of patient, tumour and treatment factors. Radiation therapy time factors assessed were PFRTD and time interval from surgery to commencement of RT (SRTD). The end-point assessed was RFS and analysis was performed using Cox regression and Kaplan-Meier survival. One hundred and eighty-nine children were identified from 10 oncology units, with data available from 182 children for analysis. Median follow up was 5.3 years. Seventy-three per cent of children presented with disease confined to the cerebellum; 13% had initial neuraxis disease. Macroscopic resection was described in 54%; 42% received adjuvant chemotherapy. Median RT dose and RT duration to PF was 55 Gy and 45 days, respectively. Seventy-eight relapses occurred with a 10-year actuarial RFS of 58.2% (standard error +/- 4%). On univariate analysis, increasing PF dose (P = 0.002), age >5 years (P = 0.006), and more thorough extent of surgical resection (P = 0.043) were associated with improved RFS; PFRTD (P = 0.20) and SRTD (P = 0.51) were not associated with RFS. On multivariate analysis, although both PF dose (P = 0.004) and extent of surgery (P = 0.045) remained strongly significant, RT duration was now associated with RFS (P = 0.049). Other factors assessed that did not reach significance were patient age, local tumour extent, presence of internal shunt and use of chemotherapy. The importance of local treatment factors was confirmed in this audit with established prognostic factors such as primary tumour macroscopic resection and adequate PF RT dose being associated with RFS. A treatment time effect is weakly suggested, although less significant than RT dose delivered.

Adolescent↗
PubMed2005

Interpreting the improved outcome of patients with central nervous system metastases managed in clinical trials compared with standard hospital practice.

The aims were to determine the median survival and prognostic factors of patients with central nervous system (CNS) metastases managed with whole-brain radiation therapy (WBRT), and to explore selection criteria in recently published clinical trials using aggressive interventions in CNS metastases. A retrospective audit was performed on patients managed with WBRT for CNS metastases. Potential prognostic factors were recorded and analysed for their association with survival duration. The proportion of patients with these factors was also compared with those of patients managed under three recently reported studies investigating aggressive interventions, such as radiosurgery and chemotherapy for CNS metastases. Seventy-three patients were treated with WBRT for cerebral metastases over a 12-month period. The median survival of the population was 3.4 months (95% confidence interval: 2.7-4.1), with 6- and 12-month survival rates of 30 and 18%, respectively. Significant prognostic factors for prolonged median survival were Eastern Cooperative Oncology Group status 0-2 (P = 0.015), Medical Research Council neurological functional status 0-1 (P = 0.006), and Recursive Partitioning Analysis Class 2 versus Class 3 (P = 0.020). On multivariate analysis, younger patient age (P = 0.02) and better performance status (P < 0.01) were associated with improved outcome. When comparing these characteristics with selected published studies, our study cohort demonstrated a higher proportion of patients with poor performance status, a greater number of metastases per patient and a higher incidence of extracranial disease. This reflects the selected nature of patients in these published studies. Central nervous system metastases confer a poor prognosis and, for the majority of patients, aggressive interventions are unlikely to improve survival. The use of potentially toxic and expensive treatments should be reserved for those few in whom these studies have shown a potential benefit.

Aged↗
PubMed2004

Impact of radiation therapy on acute toxicity in breast conservation therapy for early breast cancer.

AIMS: To document the acute toxicity experienced by women receiving radiation therapy as part of breast-conservation therapy (BCT) for early breast cancer. MATERIALS AND METHODS: A retrospective review was undertaken of the medical records of 234 consecutive women managed with radiation therapy for BCT over a 2-year period. A policy of formal acute toxicity documentation was present during this period with descriptive measures as well as the Radiation Therapy Oncology Group (RTOG) acute toxicity scoring system. Cutaneous moist desquamation, peak RTOG score, breast oedema and chemotherapy dose intensity were end points assessed. Patient and treatment characteristics were investigated for their association with study end points using Chi-squared and logistic regression analyses. RESULTS: A total of 223 (95%) of women had data available for analysis. All women were treated with tangential fields on megavoltage linear accelerators. Eighty-three (37.2%) women had systemic chemotherapy either delivered simultaneously in 58 and sequentially in 25. Moist desquamation occurred in 70 (31.4%) women; principally in the inframammary fold only in 43 (19.3%). Only 12 (5.4%) had a confluent moist reaction. Two hundred and ten (94%) women had a peak RTOG skin grade of 2 or less. Breast oedema was evident at treatment end in 46 (20.5%). On univariate analysis, physical factors, such as patient weight (P<0.001) and breast size (P<0.001), were significantly associated with moist desquamation, as were the volume of breast resected (P=0.02) and the use of chemotherapy (P=0.03). Only the physical factors remained significant on multivariate analysis. The presence of breast oedema was associated with surgical factors such as post-operative oedema (P<0.001) and infective complications (P<0.001). The use of concurrent chemoradiotherapy did not affect chemotherapy dose intensity, nor did the presence of moist desquamation increase the risk of febrile complications in chemotherapy-related neutropenia. CONCLUSION: This study confirms the relatively low incidence of significant acute toxicity experienced by women during radiation therapy as part of BCT. These study data should assist surgeons and women in the decision-making process for BCT.

Adult↗
PubMed2000

Pilot study of high-frequency ultrasound to assess cutaneous oedema in the conservatively managed breast.

Cutaneous oedema is a relatively frequent complication in patients treated conservatively for breast cancer. The factors that contribute to this complication have not been precisely determined. We performed a pilot study to assess the usefulness of high-frequency ultrasound as a quantitative measure of cutaneous oedema. Eleven patients undergoing breast-conserving therapy for breast cancer were studied. Both the treated and untreated breasts were examined. Total cutaneous thickness provided a useful measure of cutaneous oedema. The treated breast was significantly thicker than the untreated breast (P < 0.001). The medial aspect of the breast was thicker than the lateral aspect in both the treated and untreated breast (P < 0.001). The increase in cutaneous thickness predated radiotherapy in those patients who had undergone an axillary dissection. Intrapatient variation in skin thickness was much less than interpatient variation in skin thickness (coefficient of variation 6.4% vs. 18.2% for the untreated breast; coefficient of variation 13.9% vs. 30.9% for the treated breast). Increasing cutaneous thickness was associated with decreasing cutaneous echodensity. We were unable to derive quantitative estimates of echodensity. Cutaneous oedema is an important outcome variable following conservative treatment of breast cancer. High-frequency ultrasound is able to quantify this accurately. It can readily detect changes invisible to the naked eye. High-frequency ultrasound should enable the effects of different treatment options (e.g., extent of surgery, radiotherapy, and chemotherapy) on cutaneous oedema to be differentiated and for the time course of oedema to be accurately characterised.

Aged↗
PubMed2000

Three-dimensional dose distribution of tangential breast irradiation: results of a multicentre phantom dosimetry study.

BACKGROUND AND PURPOSE: One aspect of good radiotherapeutic practice is to achieve dose homogeneity. Dose inhomogeneities occur with breast tangent irradiation, particularly in women with large breasts. MATERIALS AND METHODS: Ten Australian radiation oncology centres agreed to participate in this multicentre phantom dosimetry study. An Alderson radiation therapy anthropomorphic phantom with attachable breasts of two different cup sizes (B and DD) was used. The entire phantom was capable of having thermoluminescent dosimeters (TLD) material inserted at various locations. Nine TLD positions were distributed throughout the left breast phantom including the superior and inferior planes. The ten centres were asked to simulate, plan and treat (with a prescription of 100 cGy) the breast phantoms according to their standard practice. Point doses from resultant computer plans were calculated for each TLD position. Measured and calculated (planning computer) doses were compared. RESULTS: The dose planning predictability between departments did not appear to be significantly different for both the small and large breast phantoms. The median dose deviation (calculated dose minus measured dose) for all centres ranged from 2. 3 to 5.3 cGy on the central axis and from 2.1 to 7.5 cGy for the off-axis planes. The highest absolute dose was measured in the inferior plane of the large breast (128.7 cGy). The greatest dose inhomogeneity occurred in the small breast phantom volume (median range 93.2-105 cGy) compared with the large breast phantom volume (median range, 100.1-107.7 cGy). There was considerable variation in the use (or not) of wedges to obtain optimized dosimetry. No department used 3D compensators. CONCLUSION: The results highlight areas of potential improvement in the delivery of breast tangent radiotherapy. Despite reasonable dose predictability, the greatest dose deviation and highest measured doses occurred in the inferior aspects of both the small and large breast phantoms.

Breast Neoplasms↗
PubMed2000

Does prosthetic covering of nitinol stents alter healing characteristics or hemodynamics?

PURPOSE: To evaluate placement of polyester (Dacron) coverings on nitinol stents implanted in the canine aorta to determine the effect on cross-sectional lumen area, development of intimal hyperplasia, device endothelialization, and flow hemodynamics. METHODS: Ten polyester-covered and 10 uncovered nitinol stents (60-mm length, 10- or 12-mm diameter) were deployed percutaneously in the normal infrarenal aorta of 20 adult mongrel dogs using random assignment. Angiography, intravascular ultrasound (IVUS), and duplex ultrasound performed at device deployment and before explantation at 6 weeks were used to measure aorta/device diameter and cross-sectional area. Pressure-perfusion-fixed aortic segments were compared for surface endothelialization (CD31 staining) and for thickness of neointimal formation. RESULTS: All 20 endoluminal devices were accurately positioned in the infrarenal aorta without early or delayed evidence of device thrombosis, significant lumen narrowing, or device deformity. IVUS and duplex scanning identified no anatomical stenosis in either the covered or the bare devices by duplex ultrasound; peak systolic velocity measurements were similar (106+/-25 cm/s in the covered stent versus 96+/-25 cm/s for bare stents, p > 0.05). Mean neointimal thickness was significantly greater (p < 0.005) in the covered (326+/-145 microm) compared with the bare (219+/-62 microm) stents. Intima-to-media height ratios were greater in the covered stents (3.0+/-1.1 compared with 1.1+/-0.2, p < 0.003). Mean surface area endothelialization in the proximal, middle, and distal sections of each device was similar (p > 0.05) in covered (59%, 56%, and 69%) and bare (59%, 65%, and 53%) stents. CONCLUSIONS: Deployment and balloon dilation of a covered nitinol stent in a nondiseased canine aorta increased neointimal development compared with an uncovered stent, but overall lumen cross-sectional area was preserved. No differences in device patency, intradevice thrombus formation, flow hemodynamics, or luminal endothelialization were demonstrated, despite a thicker intradevice neointima induced by the polyester covering.

Alloys↗
PubMed1998

Do inflammatory processes contribute to radiation induced erythema observed in the skin of humans?

BACKGROUND: Two prospective trials were designed to determine whether there may be a role for inflammatory mediators in human skin erythema at both high and low doses per fraction and for 'out of field' effects. METHODS: Trial 1. Effects of topical indomethacin (1%) and hydrocortisone (1%) applied before and during radiotherapy were compared for erythema induced by 20 Gy in four fractions (n = 26, 6 MV). Trial 2. Effects of topical hydrocortisone (1 %) applied before and during radiotherapy and no medication were compared for erythema induced by 1, 3, 5 and 7 Gy in five fractions (n = 21, 120 kV). Erythema was measured using reflectance spectrophotometry (RFS) and laser Doppler (LD) on a weekly basis. RESULTS: Trial 1. A bi-phasic reaction time course was suggested in two-thirds of the cases. The first phase did not appear to be influenced by hydrocortisone cream but the second was significantly attenuated. Indomethacin had no effect on either reaction phase. Erythema measured several centimetres outside of the field was reduced by hydrocortisone but not by indomethacin. Trial 2. Trial 2 confirmed the presence of measurable erythema, invisible to the eye, that coincided in its time course to the first phase of erythema noted in trial 1. This reaction was more intense than predicted by the LQ formula and was non-significantly attenuated by topical hydrocortisone. RFS readings proved to be less subject to inter- and intra-patient variations than the LD unit used. CONCLUSION: Inflammatory responses may play a role in the mediation of the erythematous response to radiation in human skin. Further studies are warranted.

Aged↗
PubMed1998

Immobilised heparin accelerates the healing of human wounds in vivo.

Locally produced growth factors are of great importance in wound healing in human skin. Wound fluid from chronic wounds contains low concentrations of growth factors possibly because of rapid degradation as a result of the high concentration of proteases. Many growth factors involved in wound healing bind to heparin and are thereby stabilised and activated. We have recently shown that heparin in combination with chitosan stimulates re-epithelialisation in an in vitro model of human wound healing. In the present study we investigated the effects of a chitosan-heparin membrane on wound healing in 10 split-thickness graft donor sites in human skin. The chitosan-heparin membrane stimulated healing of the donor sites both when judged macroscopically in a blinded fashion and when biopsy specimens from the treated and untreated parts of the wound were investigated microscopically. We hypothesise that the beneficial effects of the chitosan-heparin membrane result from slow release of heparin into the wound area which protects locally produced growth factors. The result is increased stabilisation and concentration of growth factors in the wound area, which stimulate healing. We believe that these results may be important in the treatment of wounds that are reluctant to heal.

Biocompatible Materials↗
PubMed1998

High dose behind inhomogeneities during medium-energy x-ray irradiation.

Medium-energy x-rays from orthovoltage treatment units are used for a variety of radiotherapy treatments ranging from cutaneous malignancies in the head and neck region to bone metastases. It was the aim of the present study to investigate the dose distribution due to secondary electrons close behind inhomogeneities in these radiation qualities. The dose was assessed in a solid water phantom using three plane-parallel ionization chambers (NE 2532/2, 'Markus' and 'Attix' chamber) and sheets of aluminium, copper, zinc, platinum, lead and bone equivalent material. The depth dose distribution directly behind the inhomogeneity was assessed using sheets of 15 microm thick polyethylene foil. A dose increase was found directly behind inhomogeneities of high atomic number with a rapid dose fall-off over the first 100 microm. The dose downstream of the inhomogeneity was found to increase with increasing beam quality from 120 kVp (HVL 2.8 mm Al) to 250 kVp (HVL 2 mm Cu). In the latter the dose was increased directly behind lead and platinum sheets by up to a factor of eight compared with a solid water depth of similar attenuation. The results of the study demonstrate the importance of using appropriate materials if shielding is in contact with the patient.

Bone Neoplasms↗
PubMed1998

How should we introduce high-dose chemotherapeutic strategies into the adjuvant management of high-risk breast cancer in Australasia?

BACKGROUND: Development of bone marrow support techniques has altered the standard chemotherapeutic management of haematological malignancies, and these techniques are now being increasingly utilized in solid tumours. In breast cancer, survival benefits have resulted from conventional dose adjuvant chemotherapy, but outcomes remain poor in many women with high-risk disease. Improved response rates with high-dose chemotherapy (HDC) in metastatic disease have led to the investigation of these techniques in adjuvant therapy of high-risk localized disease. In some high-risk patient subgroups survival is extremely poor, with 5-year rates below 30%. Improved adjuvant strategies for patients in these subgroups are therefore urgently required. In Australasia, oncology departments are currently considering accrual of women with high-risk disease into the International Breast Cancer Study Group (IBCSG) 15-95 Trial investigating HDC/stem cell transplantation. METHODS: The present paper reviews the available data on the efficacies and toxicities of currently available high-dose chemotherapeutic strategies; discussing methodological considerations relevant to their introduction and safe use in the adjuvant setting in Australia and New Zealand. RESULTS: Although response rates with HDC in metastatic disease are encouraging, the clinical effectiveness of current HDC regimens in adjuvant management has not been established and is limited by significant toxicity. CONCLUSIONS: The introduction of HDC strategies for high-risk breast cancer in Australia encounters difficulties both in trial design and potential clinical practice.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1997

Blunt disruption of the abdominal aorta: report of a case and review of the literature.

A 71-year-old woman had an abdominal aortic disruption as a belted passenger in a motor vehicle accident. The diagnosis was unexpected, and the patient died during surgery. There have been 54 patients operated with this diagnosis since 1953; our patient was the fifty-fifth. This is an unusual injury, because the aorta is well protected in this position. Thoracic aortic injuries are much more common (20 times) than abdominal injuries. The causes are motor vehicle accidents, blows to the abdomen, explosions, and falls. Obstructing lesions such as thrombosis and intimal dissection are the more common presentation. False aneurysms occur occasionally. Free rupture has a very high and immediate mortality rate, and few patients arrive at the hospital alive. Diagnosis can be clinical, based on distal ischemia and neurologic abnormalities, or made with Doppler scanning, ultrasonography, computed tomography, or arteriography. Two thirds present acutely and one third subsequently months or even years after the original injury. Treatment consists of flap suture, thrombectomy, bypass grafting in more extensive injury, or extra-anatomic bypass in the face of severe contamination. Recently, endoluminal stenting has successfully been used, avoiding an abdominal operation completely.

Accidents, Traffic↗
PubMed1997

Heparin-chitosan complexes stimulate wound healing in human skin.

The effect of heparin ionically linked to chitosan on the stimulation of re-epithelialisation of full thickness wounds in human skin was investigated in an in vitro model. After seven days of incubation, heparin-chitosan gel stimulated 9/10 of the full thickness wounds to re-epithelialise compared with only 3/10 of the wounds that were covered with chitosan gel or membrane, and none of the wounds incubated without gel or membrane or with heparin solution alone. Both dermal and epidermal cells were viable after the incubation time. Furthermore, the stimulatory effect of the heparin-chitosan complexes depended on the concentration of heparin in the complex. We hypothesise that these effects are caused by stabilisation and activation of growth factors that bind to immobilised heparin.

Biocompatible Materials↗
PubMed1994

New device for visual neodymium:YAG laser prostate ablation: acute and chronic canine evaluation.

This canine study (n = 6) evaluated the acute and chronic effects of Nd:YAG laser prostatectomy using a Prolase II fiber. The Prolase II device consists of a 1,000 microns quartz fiber which directs a cone of Nd:YAG laser energy, at 45 degrees to the axis of the fiber, into the prostatic urethra under direct visual guidance [visual laser ablation of prostate, (VLAP)]. Under visual guidance and saline irrigation, 60 seconds of 60 watts of laser power was delivered at 3, 6, 9, and 12 o'clock positions (14,400 J). One canine was instrumented but received no laser energy (control). One prostate was harvested acutely. The remaining four laser-treated dogs were evaluated at 6 to 16 weeks. The histopathology of acute laser effects shows areas of necrosis with loss of glandular structures and stromal edema. Surrounding this area was a zone of degenerative glandular structures extending up to 12.6 mm into the prostate. Two of the four dogs developed urinary retention at 6.5 and 9 weeks. On examination, both were found to have fibrotic strictures at the distal prostatic urethra with markedly dilated proximal prostatic urethral lumens (1.98 and 2.8 cm). Two other dogs showed no signs of urinary retention at sacrifice. Histopathology, both the 6 and 16 week laser-treated animals without urinary retention demonstrated dilated prostatic urethras with maximum cross-sectional diameters of 1.52 and 1.50 cm, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Innovations in vascular imaging: arteriography, three-dimensional CT scans, and two- and three-dimensional intravascular ultrasound evaluation of an abdominal aortic aneurysm.

This report compares the information obtained from arteriography, CT scans, and intravascular ultrasound evaluation of an abdominal aortic aneurysm. The two- and three-dimensional imaging techniques described in this report add information that is redefining the pre- and intraoperative analysis of arterial lesions. The new data may have an influence on the evolution of diagnostic methods and future interventional therapy for vascular disease. This case highlights the developing potential of the methods.

Aged↗
PubMed1994

Changes in arterial wall compliance after endovascular stenting.

PURPOSE: The response of arterial wall to endovascular stenting after angioplasty is not well understood. Additionally, changes in the elastic properties of stented vessels are unknown in situ. Vascular compliance was measured in normal canine iliac arteries (n = 11) before and after intravascular ultrasound-guided deployment of self-expandable metallic stents. METHODS: Nine animals were restudied and killed 1, 2, and 4 weeks after initial deployment, and two dogs were studied at deployment only. An absolute induction angiometer was used to make in situ measurements of vessel compliance via catheter-based delivery. The angiometer consists of a wire loop probe, which conforms to the diameter of the vessel in which it is placed. Systolic/diastolic changes in loop diameter are translated into measureable changes of induced voltage. RESULTS: Mean compliance of the artery before and immediately after stenting was 4.4 +/- 2.1 and 1.9 +/- 2.0 (x 10(-2) diameter %/mm Hg), respectively. As early as 1 week after deployment, stented arteries began to lose expansile properties, and some were noncompliant. At explantation diminished compliance was accompanied by a periadventitial fibrous reaction around stented vessels. A thin, unobstructing layer of neointimal hyperplasia covered the iliac stents at all intervals, and all vessels remained patent and free of thrombus. CONCLUSIONS: The potential advantages provided by a flexible, radially compliant stent are lost within a relatively short time after implantation in nonatherosclerotic canine arteries.

Animals↗