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Biomedical subjects

P Cross

Publications and source records attributed to P Cross.

At least 37 records · Page 2Linked to original sources
PubMed2000

Conservative surgery and radiation therapy for early stage breast cancer after previous mantle radiation for Hodgkin's disease.

There is an increased incidence of breast cancer in female patients who have previously undergone mantle radiation for Hodgkin's disease. Lumpectomy followed by breast irradiation is generally considered to be contraindicated in such patients owing to the high cumulative radiation dose to the breast. Mastectomy is therefore recommended as the preferred treatment option in these women. We report two cases of breast cancer occurring in women previously treated with mantle radiation for Hodgkin's disease. Both women declined mastectomy and requested breast-conserving treatment.

Adult↗
PubMed2000

MedCERTAIN: quality management, certification and rating of health information on the Net.

MedCERTAIN (MedPICS Certification and Rating of Trustworthy Health Information on the Net, http://www.medcertain.org/) is a recently launched international project funded under the European Union's (EU) "Action Plan for safer use of the Internet. It provides a technical infrastructure and a conceptual basis for an international system of "quality seals", ratings and self-labelling of Internet health information, with the final aim to establish a "trustmark" for networked health information. Digital "quality seals" are evaluative metadata (using standards such as PICS = Platform for Internet Content Selection, now being replaced by RDF/XML) assigned by trusted third-party raters. The project also enables and encourages self-labelling with descriptive meta-information by web authors. Together these measures will help consumers as well as professionals to identify high-quality information on the Internet. MedCERTAIN establishes a fully functional demonstrator for a self- and third-party rating system enabling consumers and professionals to filter harmful health information and to positively identify and select high quality information. We aim to provide a system which allows citizens to place greater trust in networked information, exemplified in the domain of health information, whilst also making a significant contribution for similar projects with different target domains. The project will demonstrate how PICS-based content rating and filtering technologies can automate and exploit value-adding resource description services. It further proposes standards for interoperability of rating services.

Databases as Topic↗
PubMed1999

Concurrent chemotherapy with hyperfractionated accelerated thoracic irradiation in stage III non-small cell lung cancer.

OBJECTIVES: We evaluated the effect of hyperfractionated accelerated radiotherapy combined with low dose radiosensitisers followed by standard dose chemotherapy in the treatment of unresectable stage III non small cell lung cancer (NSCLC). METHODS: Forty-seven patients received thoracic radiotherapy (1.5 bid x 5 days x 4 weeks) in combination with low dose daily (3-6 mg/m2) cisplatin +/- weekly vinblastine chemotherapy (step I), followed by three cycles of standard dose chemotherapy alone consisting of cisplatin (75-80 mg/m2) and vinblastine (8-16 mg/m2) given at 3-4 week intervals (step II). RESULTS: The overall response rate was 70% (21% CR). The progression free interval and the median survival duration were 10.4 months and 17.3 months, respectively. The 3 year survival rate was 21%. The site of first progression was local in 44%, distant in 41%, and simultaneous in 15% of patients. Levels of esophageal toxicity were significant but acceptable with the use of prophylactic therapy. Grade 3 or 4 esophageal toxicity was observed in 28 and 19% of patients during step I and II of the study, respectively. There were three deaths associated with esophageal toxicity. All occurred prior to the implementation of the prophylactic therapy for esophagitis. Acute pulmonary symptoms were reported in 25% of patients in step I, and pulmonary fibrosis, primarily asymptomatic, was observed in 51% of patients. Hematological toxicity was moderate. Two patients died of neutropenic sepsis/pneumonia. CONCLUSION: Concurrent chemotherapy and hyperfractionated accelerated radiotherapy followed by chemotherapy appears moderately effective in controlling tumour growth as measured by response rates and survival estimates. Toxicity is considerable but manageable and compatible with results from other combined modality studies.

Adult↗
PubMed1999

Description of a new motor re-education programme for the paretic lower limb aimed at improving the mobility of stroke patients.

OBJECTIVE: To describe and examine the feasibility of a new treatment approach for the paretic lower limb and to explore its effectiveness in one chronic hemiparetic stroke subject. DESIGN: Case report. The treatment was conducted three times per week over a period of six weeks. The mobility of the patient was assessed prior to the treatment, at the end of the treatment and at a six-week follow-up. SETTINGS: The study was carried out at the research centre of the Institut de réadaptation de Montréal. The treating therapist was an experienced rehabilitation professional as was the assessor, who worked at a different rehabilitation centre. INTERVENTIONS: The motor re-education programme was based on the use of a static dynamometer that measures the linear external forces produced at the ankle level. A computer program provided the subject with constant feedback on the direction and intensity of the applied force. In each treatment session, the subject was asked to produce several submaximal efforts in 16 specific directions. Both the intensity and the number of repetitions were gradually increased. OUTCOME MEASURES: In addition to force production measurements, three clinical assessments of mobility were used: the Timed 'Up and Go', the comfortable gait speed and a 2-minute walk test. RESULTS: The maximal static linear forces produced by the subject increased through the treatment for all directions of effort, but differences were observed amongst directions. During the treatment programme, the subject improved his performance at the three clinical assessments. Even if some of the functional gain was lost at the follow-up, the mobility was still considerably improved as compared to baseline values. CONCLUSION: This study demonstrated the applicability of the treatment programme to a stroke subject. The results seem very promising and encourage further investigation in order to assess more rigorously the effectiveness of this new approach.

Adult↗
PubMed1998

Prognostic factors derived from recursive partition analysis (RPA) of Radiation Therapy Oncology Group (RTOG) brain metastases trials applied to surgically resected and irradiated brain metastatic cases.

PURPOSE: (a) To identify the prognostic factors that determine survival after surgical resection and irradiation of tumors metastatic to brain. (b) To determine if the prognostic factors used in the recursive partition analysis (RPA) of brain metastases cases from Radiation Therapy Oncology Group (RTOG) studies into three distinct survival classes is applicable to surgically resected and irradiated patients. METHOD: The medical records of 125 patients who had surgical resection and radiotherapy for brain metastases from 1985 to 1997 were reviewed. The patients' disease and treatment related factors were analyzed to identify factors that independently determine survival after diagnosis of brain metastasis. The patients were also grouped into three classes using the RPA-derived prognostic parameters which are: age, performance status, state of the primary disease, and presence or absence of extracranial metastases. Class 1: patients < or = 65 years of age, Karnofsky performance status (KPS) of > or =70, with controlled primary disease and no extracranial metastases; Class 3: patients with KPS < 70. Patients who do not qualify for Class 1 or 3 are grouped as Class 2. The survival of these patients was determined from the time of diagnosis of brain metastases to the time of death. RESULTS: The median survival of the entire group was 9.5 months. The three classes of patients as grouped had median survivals of 14.8, 9.9, and 6.0 months respectively (p=0.0002). Age of < 65 years, KPS of > or = 70, controlled primary disease, absence of extracranial metastases, complete surgical resection of the brain lesion(s) were found to be independent prognostic factors for survival; the total dose of radiation was not. CONCLUSION: Based on the results of this study, the patients and disease characteristics have significant impact on the survival of patients with brain metastases treated with a combination of surgical resection and radiotherapy. These parameters could be used in selecting patients who would benefit most from such treatment.

Adult↗
PubMed1998

The relationship between biochemical failure and time to nadir in patients treated with external beam therapy for T1-T3 prostate carcinoma.

PURPOSE AND BACKGROUND: To determine a prostatic-specific antigen (PSA) nadir value and time to nadir that predict a high probability of freedom from biochemical failure in men treated with external beam therapy for prostate cancer. MATERIALS AND METHODS: Between January 1990 and March 1994, 228 men with T1-T3 adenocarcinoma of the prostate received a radical course of external beam irradiation with no prior or adjuvant hormonal therapy. All men had pre- and post-treatment serum PSA evaluations, and were followed up for at least 24 months, to ensure PSA nadir was reached. Biochemical failure was defined as three successive post-treatment rises in serum PSA, regardless of the magnitude of elevation. RESULTS: Overall, 4-year biochemical disease-free survival (BDFS) was 42%. PSA nadir was predictive of subsequent BDFS. For those whose serum PSA nadir was < or =1 ng/ml, 4-year BDFS was 70%, versus 12% for those with serum PSA nadir > 1 ng/ml (P = < 0.001). The 4-year BDFS for patients with time to nadir < or =1 year, was 28%, versus 58% for those with time to nadir > 1 year (P < 0.001). For patients with PSA nadir < or =1 ng/ml, 4-year BDFS was 75% for those with time to nadir > 1 year, versus 61% for those with time to nadir < or =1 year (P < 0.021). In multivariate analysis, PSA nadir(< or =1 ng/ml versus >1 ng/ml, and time to nadir (< or =1 year versus > year) were independent predictors of BDFS alone with pre-treatment PSA and Gleason score. CONCLUSION: Only those who achieved PSA nadir < or =1 ng/ml following external beam therapy have a favourable chance of lasting biochemical disease control, while those with nadir > 1 ng/ml have a high subsequent failure rate. The prognosis is better in patients with late time to nadir. In addition to PSA nadir, time to nadir, pretreatment PSA, and Gleason score were of independent prognostic significance.

Actuarial Analysis↗
PubMed1998

Lectins in the vulva. I. Normal vulvar epithelium and epithelium adjacent to vulvar intraepithelial neoplasia and squamous cell carcinoma.

Lectins were used to investigate the cell surface oligosaccharide expression in normal vulvar epithelium from premenopausal and postmenopausal volunteer women. In addition, histologically normal epithelium adjacent to high-grade vulvar intraepithelial neoplasia (VIN III) and adjacent to vulvar tumors was examined with lectins for evidence of a possible "field change" surrounding these vulvar lesions. Seventeen vulvar biopsies were obtained prospectively from volunteer women, and 20 and 40 cases, respectively, of VIN III and vulvar squamous cell carcinoma were randomly chosen from pathology archives. Thirteen of the 20 VIN cases and all 40 vulvar carcinomas contained at least 2 cm of histologically normal-appearing epithelium adjacent to the vulvar lesion suitable for analysis. No alterations to lectin binding in normal vulvar epithelium with respect to patient age, menopausal status, phase of menstrual cycle, estrogen therapy, or history of cervical intraepithelial neoplasia were shown. ABO blood group antigen status affected epithelial binding for lectins HPA and UEAI (p < 0.005 and p < 0.001, respectively). In addition, lectins SNA, MPA, and LCA identified markers of cellular differentiation and maturation. T-antigen expression (as shown by the lectin PNA) was almost universally present in histologically normal epithelium adjacent to VIN and vulvar tumors, contrasting with the lack of PNA binding in normal vulvar epithelium from volunteer women (p < 0.001 and p < 0.001), a finding suggestive of a local "field change" surrounding preinvasive and invasive vulvar lesions.

ABO Blood-Group System↗
PubMed1998

Lectins in the vulva. II. Vulvar intraepithelial neoplasia and squamous cell carcinoma.

This study used lectins as histologic probes to determine the cell surface oligosaccharide expression in different grades and types of vulvar intraepithelial neoplasia (VIN). Lectin binding patterns in metastasizing and non-metastasizing squamous cell carcinomas (SCCs) of the vulva were also compared to correlate lectin binding patterns with metastatic potential and other clinical/tumor characteristics. Twenty cases each of VIN epithelium, metastasizing SCC, and non-metastasizing vulvar carcinoma were randomly chosen from the pathology archives. Sixteen lectins were used to probe individual terminal oligosaccharide residues in formalin-fixed, paraffin-embedded tissue specimens from these cases through an indirect immunohistochemical technique. There were no differences in lectin binding patterns between the different histologic subtypes of VIN. In addition, there were no consistent differences between metastasizing and non-metastasizing primary tumors and no major differences in staining patterns between nodal metastases and the corresponding primary tumors. Furthermore, there was no identifiable correlation between lectin binding patterns and subsequent survival or local or regional recurrence; however, lectin staining of invasive tumor cells did appear to be related to local invasiveness. In addition, positive PNA binding was found to be a constant finding in each of the VIN and invasive SCC cases, confirming that the T-antigen becomes unmasked during the process of vulvar carcinogenesis. However, poorly-differentiated areas consistently showed absent lectin binding, suggesting loss of specific glycosyl transferase activities. In addition, the blood group "A" antigen appears to be lost during the process of tumorgenesis, although the blood group "O" antigen appears to be preserved.

Carcinoma in Situ↗
PubMed1998

Is prostate specific antigen density an important prognostic indicator for patients with prostate cancer treated with external beam therapy?

The purpose of this study was to determine if prostate specific antigen density (PSAD) is a predictor of outcome following external beam radiotherapy for prostate cancer, and to compare it with other prognostic factors. Between January 1990 and December 1993, 205 patients with T1-T3 adenocarcinoma of the prostate received a radical course of external beam irradiation, with no prior or adjuvant hormonal therapy. All patients had pre- and post-treatment serum prostate specific antigen (PSA) evaluation. They were followed up for at least 24 months. PSAD was defined as the ratio of pre-treatment serum PSA to the prostate volume, as determined from CT treatment planning scans. Prostate volumes were calculated using the prostate ellipse formula. Median PSA density was 0.37, with a range 0.01-6.7. Biochemical failure was defined as three consecutive rises in serum PSA, regardless of the magnitude of elevation. 4-year biochemical disease-free survival (BDFS) for patients with PSAD < or = 0.3 was 60%, compared with 22% for patients with PSAD > 0.3 (p = < 0.001). In a multivariate analysis, pre-treatment PSA (p = < 0.001), Gleason score (p = 0.002), and stage (p = 0.03) were independent predictors of BDFS, while PSAD was not an important prognosticator (p = 0.62). Pre-treatment serum PSA is the most important prognosticator of BDFS, following external beam radiotherapy, for patients with prostate cancer. PSA density did not predict treatment outcome.

Adenocarcinoma↗
PubMed1998

Determination of CT scanner radiation output: correction factors for partial irradiation of thimble and pencil ionisation chambers by collimated fan beams.

CT radiation output (mGy mAs-1) measured free-in-air on axis is required for compliance testing protocols. It can also be used as an input parameter for computer programs for patient dose assessment for a range of CT examinations. Output correction factors have been investigated as a function of collimation width for two chambers; an in-beam, 6 cc general diagnostic chamber, and a 3 cc pencil CT chamber. For irradiation by a fan beam perpendicular to the chamber axis, a correction factor given by the ratio, chamber active length to beam collimation width, is applicable to within +/- 5% of a measured ratio for the pencil CT chamber. However, this is not the case for the short 6 cc thimble chamber where an exponential function was found to fit the data to within similar limits. It is recommended that a pencil chamber be used for determining radiation output in air for a CT scanner. For a given scan condition static measurements are only required, obviating a need for sequential movements of an occluded small volume chamber to sample a radiation profile.

Radiation Dosage↗
PubMed1997

Fetal dose for a patient undergoing mantle field irradiation for Hodgkin's disease.

In order to safely treat a 23 weeks pregnant woman for supradiapharagmatic Hodgkin's disease, without compromising the fetus, a custom shielding table was constructed and extensive phantom measurements were performed. For 10 MV photons, the optimal shielding combination was found to consist of a 5 cm thick lead sheet placed onto a 1.25 cm aluminum supporting plate. The structure was placed directly above the phantom, over the region corresponding to the woman's abdomen, without any intervening air gap. By this means the dose to the fetus from machine leakage and collimator scatter was eliminated; the only remaining dose was due to in-phantom scatter. The woman was treated using a mantle field to a dose of 35 Gy in 20 fractions. The accumulated dose to the woman's uterine fundus and to her pubis were monitored with theroluminescent dosimeters. After completion of mantle therapy the doses to the fundus and pubis were 10 and 3 cGy, respectively. The fetal exposure was thus limited to below 10 cGy, within the zone of fetal tolerance. A normal infant was delivered at term.

Female↗
PubMed1997

The calibration of plane parallel ionisation chambers for the measurement of absorbed dose in electron beams of low to medium energies. Part 2: The PTW/MARKUS chamber.

The purpose of Part 2 study of calibration methods for plane parallel ionisation chambers was to determine the feasibility of using beams of calibration of the MARKUS chamber other than the standard AAPM TG39 reference beams of 60Co and a high energy electron beam (E0 > or = 15 MeV). A previous study of the NACP chamber had demonstrated an acceptable level of accuracy with corresponding spread of -0.5% to +0.8% for its calibration in non-standard situations (medium to low energy electron and photon beams). For non-standard situations the spread in NDMARKUS values was found to be +/-2.5%. The results suggest that user calibrations of the MARKUS chamber in non-standard situations are associated with more uncertainties than is the case with the NACP chamber.

Calibration↗
PubMed1996

The calibration of plane parallel ionisation chambers for the measurement of absorbed dose in electron beams of low to medium energies. Part 1: the NACP chamber.

A study was made of calibrating the NACP plane parallel chamber in electron beams from linear accelerators of a different manufacture with energies, Ep,o' from 4.4 to 19.1 MeV, and also in 4 and 6 MV photon beams as well as a cobalt60 beam. The photon beam measurements were both IN-AIR and IN-PHANTOM. With the exception of the lowest energy electron beam (nominal 5 MeV), the ND values from measurements in the electron beams were within +/- 1% of the average value from the three different methods according to the AAPM TG 39 protocol. The preferred method of calibration of an electron chamber is of course in an electron beam at R100 in water. This can still be done in medium energy electron beams (nominal 7 to 14 MeV) for the NACP chamber with the same degree of accuracy and precision as with AAPM TG 39 methodology. Alternatively the traditional cobalt-60 calibration beam can be replaced by a low energy (4-6MV) photon beam for in-phantom calibrations at 50 mm depth, giving comparable results, and with no more uncertainties than those obtained in electron beams.

Biophysical Phenomena↗
PubMed1995

Item bias in cognitive screening measures: comparisons of elderly white, Afro-American, Hispanic and high and low education subgroups.

A study of item bias in standard cognitive screening measures was conducted in a sample of Afro-American, Hispanic and non-Hispanic white elderly respondents who were part of a dementia case registry study. The methods of item-response theory were applied to identify biased items. Both cross-cultural and high and low education groups were examined to determine which items were biased. Out of 50 cognitive items examined from six widely used cognitive screening measures, 16 were identified as biased for either high and low education groups or ethnic/racial group membership.

Black or African American↗
PubMed1995

The estimation of lung dose from mid-perineum ionization chamber measurements in total body irradiations: a quality control check on dose delivery.

A series of patients (eleven males and eight females) receiving total body irradiation prior to bone marrow transplantation was monitored during treatment by recording the dose from an ionization chamber placed between the thighs in the mid-perineal region. The treatment was delivered by opposed lateral 6 MV photon beams. The patient was encompassed by the radiation field with the maximum collimator opening at a distance of 3.49 m from the X-ray focus to the patient mid-line. An analysis was made of the measured dose and the calculated percentage average lung dose for each patient in the series to seek a correlation between measured doses and patients' anatomical data so that estimates of delivered lung doses could be made. Whilst a global factor can be applied to measured dose to predict lung dose, it is concluded that perineal dose measurements distal to the region where dose is prescribed (mean lung dose) are sub-optimal for checks on target dose delivery. Entrance and exit dose measurements at the level of dose prescription (in the thorax) are preferable for more accurate predictions and quality control checks.

Female↗