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U Abel

Publications and source records attributed to U Abel.

At least 37 records · Page 2Linked to original sources
PubMed1998

Die Rolle der Randomisation in klinischen Studien.

The Place of Randomisation in Clinical TrialsRandomised clinical trials are nowadays the accepted gold standard for treatment comparisons. However, controversies still exist concerning the possibility to perform randomised trials or the adequacy and the ethical appropriateness of randomisation. Randomisation is sometimes credited with advantages it does not possess, and an extremely negative view or even a categorical rejection of non-randomised trials is found. This attitude may be comprehensible from a historical, pragmatic or educational viewpoint, but is not well-founded on epistemological grounds. This article argues that non-randomised clinical trials are needed, clarifies the role of randomisation in clinical trials and analyses the arguments raised against the validity of results from observational studies. It is shown that it has not been demonstrated up to now that well-designed and analysed observational studies would have yielded results that are distinct or even qualitatively different from results of similar randomised clinical trials. Although one is well advised to randomise whenever possible, there is still room for a considerable improvement of observational studies: Randomisation itself should be the only difference between observational studies and randomised clinical trials.

Journal Article↗
PubMed1996

Rapid course radiation therapy vs. more standard treatment: a randomized trial for bone metastases.

PURPOSE: In a prospective randomized trial we examined whether radiotherapy of painful bone metastases can be shortened using larger single doses without impairing effectivity. METHODS AND MATERIALS: One hundred patients with painful bone metastases having no prior surgical intervention or treatment with x-ray therapy and had a median follow-up of 12 months were analyzed. The primary tumor was located in the breast in 43%, in the lung in 24%, and in the prostate in 14%. The most frequent sites of metastases were the pelvis (31%), the vertebral column (30%), and the ribs (20%). Further percentages of sites were: lower extremity 11%, upper extremity 6%, and skull 2%. Fifty-one patients received a short course radiotherapy with a total dose of 20 Gy in 1 week (daily dose 4 Gy), and 49 patients received 30 Gy in 3 weeks (daily dose 2 Gy). RESULTS: There were no significant differences in frequency, duration of pain relief, improvement of mobility, recalcification, frequency of pathologic fractures nor survival. There was a light trend favoring 30 Gy in frequency of pain relief and recalcification. Survival was mostly influenced by primary tumor site, Karnofsky performance status, and possibly by the response to radiotherapy (pain relief). CONCLUSIONS: Because of the very short life expectancy of patients with metastatic bone disease, we now use 20 Gy in 1 week as our standard to reduce hospital stay.

Adult↗
PubMed1996

A palliative accelerated irradiation regimen (PAIR) for advanced non-small-cell lung cancer (NSCLC).

In order to avoid overtreatment in advanced NSCLC we developed a palliative accelerated irradiation regimen (PAIR) applying a total dose of 32 Gy in 10 days with two daily fractions of 2 Gy. This paper reports on a 1-year pilot study carried out in preparation of a randomised trial. Data for the 34 patients receiving PAIR were compared to 179 conventionally irradiated historical controls selected from a pre-existing database according to identical inclusion criteria. Statistical analysis showed that PAIR patients had a significantly longer survival than controls (P = 0.0029). Median survival was 11.8 and 5.8 months, respectively, while 1-year survival was 45.6% vs. 21.2%. Compared to the subgroup of controls who had received the full planned dose of 60 Gy (n = 104) PAIR patients showed no significant difference in survival. In order to adjust for possible imbalances we used a comprehensive blinded prognostic rating design creating one score value per patient out of several known prognostic factors. After adjustment for the resulting prognostic score by means of the Cox proportional hazards model PAIR patients still showed significantly longer survival. We conclude that in advanced NSCLC survival after a palliative short-term regimen appears to be at least equivalent to that following conventional high-dose irradiation.

Carcinoma, Non-Small-Cell Lung↗
PubMed1995

[Model calculations for HIV screening of blood and plasma donors with a combination of 2 screening tests: test strategies, validity, costs and effectiveness].

OBJECTIVE: The strategies for combining two screening tests for HIV infections in blood or plasma donors are formulated in biometric terms and analyzed with respect to their value, i.e. their validity, cost and effectiveness. DESIGN: Biometrical modeling using assumptions on the validity of the single tests, the conditional correlations between them, as well as on the cost of testing and the consequences of false-negative or false-positive test results. RESULTS: If the test combination is defined as positive whenever at least one of the single tests is positive, then this rule (the 'believe the positive' rule, BTP), due to its lower specificity, has extremely low positive predictive values. In case of high prevalence rates of the infection (e.g. 1:1,000), the BTP rule leads to lower total cost than single testing, unless the latter has very high sensitivity (e.g. 99%). For smaller prevalence rates (< 1:50,000), which are more typical of the selected group of blood or plasma donors, combination testing is of little value because the extra cost of detecting one additional infection (compared with single testing) may reach several 100 million DM. CONCLUSION: The cost for detecting additional cases of HIV infection by using combination instead of single testing in HIV screening is so high that this decision requires a public consensus.

AIDS Serodiagnosis↗
PubMed1994

[Growth rate of breast cancer, implication for early detection and therapeutic effects].

Numerous trials have shown, that breast cancer have highly variable rates of growth. It is assumed, that the rates (relative growth rates) decelerate with increasing tumour size. The Universities of Heidelberg and Louisville carried out a retrospective statistical analysis of the mammographically measured growth rates of 448 screening patients until breast cancer diagnosis. The analysis did not include fast-growing carcinomas appearing between mammograms for which only one mammogram was available or some cancer, where growth was not detectable by mammography. Generalized logistic curves provided the best fit to the data on the increase in tumour size, as observed in mammograms. Large variations in individual tumour doubling times were found, from extremely fast-growing to extremely slow-growing tumours. The results are relevant for patient prognosis, for the evaluation of therapy, and for screening strategies.

Adolescent↗
PubMed1993

Adjuvant randomized trials of doxorubicin/cyclophosphamide versus doxorubicin/cyclophosphamide/tamoxifen and CMF chemotherapy versus tamoxifen in women with node-positive breast cancer.

PURPOSE: We report two randomized trials of adjuvant systemic therapy in 747 patients < or = 65 years of age with histologically proven node-positive breast cancer. PATIENTS AND METHODS: Patients were selected for the two trials on the basis of lymph node and hormone receptor status. The only stratification was based on the treating institution. In patients with a lower probability of recurrence (n = 276), a comparison between endocrine therapy (tamoxifen [Tam] 30 mg/d for 2 years) and chemotherapy (cyclophosphamide, methotrexate, and fluorouracil [CMF] intravenously [IV], six cycles every 4 weeks) was performed. In patients with a higher risk of recurrence (n = 471), a comparison between chemotherapy alone (doxorubicin plus cyclophosphamide [AC] i.v., eight cycles every 3 weeks) and the same chemotherapy plus Tam was made. RESULTS: Overall, we found that CMF and Tam are equally effective in a subgroup of patients with a relatively good prognosis (low-risk patients). However, in the subset of women < or = 49 years old, a significantly greater disease-free survival (DFS) rate (P = .01) and overall survival (OS) rate (P = .002) was observed following therapy with CMF compared with Tam. In patients > or = 50 years old, the opposite was found, and Tam appeared to be superior to CMF (DFS, P = .003; OSm P = .5). These results must be interpreted cautiously, since a post-hoc stratification of patients by age (< or = 49, > or = 50) was performed, and significantly more younger, low-risk patients were randomized to receive chemotherapy alone and more older patients to receive Tam alone. Among patients with a relatively poor prognosis (high-risk patients), a combination of AC plus Tam was equivalent to AC and, when women were analyzed by age, this was found to be true of patients < or = 49 years as well. However, the addition of Tam to AC in women age > or 50 years resulted in a statistically significantly higher DFS (P = .01) and a trend toward better OS compared with women who received AC alone. CONCLUSION: Further trials are required to analyze the role of combined simultaneous or sequential chemoendocrine adjuvant treatment or each single therapy alone in defined risk-adapted subsets of node-negative and node-positive patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Chemotherapy of advanced epithelial cancer--a critical review.

This article is a short version of a report which presents a comprehensive analysis of clinical trials and publications examining the value of cytotoxic chemotherapy in the treatment of advanced epithelial cancer. As a result of the analysis and the comments received from hundreds of oncologists in reply to a request for information, the following facts can be noted. Apart from lung cancer, in particular small-cell lung cancer, there is no direct evidence that chemotherapy prolongs survival in patients with advanced carcinoma. Except for ovarian cancer, available indirect evidence rather supports the absence of a positive effect. In treatment of lung cancer and ovarian cancer, the therapeutical benefit is at best rather small, and a less aggressive treatment seems to be at least as effective as the usual one. It is possible that certain sub-groups of patients benefit from the treatment, yet so far the available results do not allow a sufficiently precise definition of these groups. Many oncologists take it for granted that response to therapy prolongs survival, an opinion which is based on a fallacy and which is not supported by clinical studies. To date, it is unclear whether the treated patients, as a whole, benefit from chemotherapy as to their quality of life. For most cancer sites, urgently required types of studies such as randomized de-escalations of dose or comparisons of immediate versus deferred chemotherapy are still lacking. With few exceptions, there is no good scientific basis for the application of chemotherapy in symptom-free patients with advanced epithelial malignancy.

Bias↗
PubMed1991

Mononuclear cells in peripheral venous blood of patients with Crohn's disease: preoperative status and postoperative course, influence of duration, activity and extent of disease.

In Crohn's disease (CD) the intestinal lesion is supposed to be the cause of the observed systemic immunologic changes. Based on this assumption, peripheral blood mononuclear cells (PBMC) are of specific interest as a possible indicator of intestinal activity of the disease. From 151 surgical patients CD3+, CD4+, CD8+, B cells, macrophages, leucocytes and the relative number of lymphocytes were analysed preoperatively and 10 days, 3 and 6 months postoperatively. The cell data were correlated with the main clinical data of disease. There was a highly significant preoperative increase of leucocytes, macrophages, CD8+, and B cells in the CD group, and a marked decrease of CD3+, CD4+ cells, and the relative lymphocyte count in the same group. Six months postoperatively, highly elevated macrophages, and leucocytes, and a depressed number of CD4+ cells were the only changes. The preoperative cell data did not correlate with the duration of illness, CDAI, localisation, and extent of the intestinal lesion nor did they correlate with any modality of preoperative drug treatment. Thus, the determination of PBMC characteristics in CD is only of limited value for routine diagnostic purposes. However, the persistence of some pathological values long after operation might be caused by residual microscopic lesions and thus reflect the intestinal process.

Adolescent↗
PubMed1991

Common infections in the history of cancer patients and controls.

The association between the frequency of manifest infectious diseases and cancer risk was investigated in a case-control study at Heidelberg, FRG. A total of 255 cases with carcinomas of the stomach, colon, rectum, breast, and ovary, as well as 255 population controls and 230 hospital controls were interviewed using a standard questionnaire. Controls were matched to the cases for age, sex, and region of residence at the time of the interview. A history of common colds or gastroenteric influenza prior to the interview was found to be associated with a decreased cancer risk. Thus the odds ratios for "three or more common colds per year (on average)" versus "no common cold within the last 5 years prior to the interview" were 0.18 (95% CI = 0.05-0.69) and 0.23 (95% CI = 0.06-0.89) relative to population controls and hospital controls, respectively. There was no apparent relationship between childhood infections or other diseases reported in the earlier history, and cancer risk. While the findings are supported by previous studies and fit well into the results of other fields of cancer research, a conclusive interpretation and biological explanation cannot yet be given.

Adult↗
PubMed1990

[Extent of psammoma carcinomas of the ovary--a clinical, DNA flow cytophotometric and morphometric image analysis study].

There is no agreement in literature on the biological behavior of psammoma carcinomas of the ovary. The majority of authors consider psammoma bodies to be the result of tumour regression, associating the occurrence of psammoma bodies with longer survival. On the other hand, several studies reveal a poor prognosis for psammoma carcinomas, similar to that of other epithelial malignant tumours. In our study, the psammoma body content in 174 serous carcinomas stage III/IV was morphometrically quantified by image analysis and the results correlated to survival time and progression time. In 20 carcinomas the psammoma body content was extremely high. In such cases, DNA flow cytometry revealed these tumours to be slowly-growing. The DNA index was 1.0 (DNA-diploid) and the number of S phases was low (max. 5.9%). The five year estimate survival was 50%, as opposed to 10% for other tumours. If no methods are available for cell kinetic analysis and for objectification and quantification of psammoma body content in serous carcinomas it is sufficient to make a semiquantitative assessment of the psammoma body content to differentiate tumours with longer survival from carcinomas of poor prognosis.

Cystadenoma↗
PubMed1989

Assessment of serial carcinoembryonic antigen: determinations to monitor the therapeutic progress and prognosis of metastatic liver disease treated by regional chemotherapy.

It is difficult, time-consuming, and expensive to evaluate the therapeutic efficacy of regional chemotherapy of metastatic liver disease by means of imaging procedures. Therefore it was the aim of this study to find out whether serial carcinoembryonic antigen (CEA) determinations yield reliable data on the therapeutic progress and the individual prognosis of these patients. Since there exists no generally accepted modality to assess CEA curves of patients receiving chemotherapy, we developed our own criterion and tested it in a group of 35 patients. For each patient an individual reference level (CEA-means) was fixed which was obtained as the arithmetical mean of serial CEA values taken during the first three courses of chemotherapy (reference time). On the basis of CEA-means the marker curves of the 35 patients could be divided into two groups. After the reference time the CEA values of group 1 (12 patients) never decreased below CEA-means. Survival of these patients was significantly (P = 0.00001) shorter than that of the 23 patients (group 2) who showed a decrease in their CEA curves below CEA-means after the reference time. Beyond this it could be observed that the improvement in survival was significantly greater in those patients who showed a CEA decrease below CEA-means for a prolonged period (3 months). This difference in prognosis is not an artefact due to different pretherapeutic conditions but is a sign of different responses to therapy. The decrease in CEA values below the individual reference level (CEA-means) is a certain sign of the efficacy of the chosen chemotherapy. A continuous rise of the CEA curve above CEA-means signifies an ineffective intrahepatic chemotherapy or extrahepatic tumor manifestation. In this case an intensive diagnostic workup of the patient and possibly a modification of the therapy are indicated.

Adult↗
PubMed1989

[Proliferation index, axillary lymph node status, hormone receptors and age as prognostic factors in primary breast cancer].

A total of 233 primary carcinomas of the breast (n = 68 nodal negative and n = 165 nodal positive) of 77 woman patients of less than 50 years of age and pf 156 women patients of 50 years of age or older were examined for the prognostic significance of a proliferation index (in vitro chemoresistance assay). The prognostic significance of the proliferation index (high vs low proliferation) is compared with other prognostic factors that have already been in clinical use (age, axillary lymph node status, oestrogen and progesterone receptor status). The total median observation period was 4.8 years (3-9.1 years). Determination of the proliferation index proved to be the most important prognostic factor both for premenopausal and postmenopausal, nodal negative and nodal positive primary tumours when assessing the total survival time and the time that remains free from recurrences. A simultaneous assessment of low proliferation index and positive hormone receptor as a so-called low-risk situation shows in comparison to a high-risk situation (high proliferation index, negative receptor status) the most pronounced differences. For premenopausal women (younger than 50 years of age) the hormone receptor status has no prognostic significance as far as our group of patients is concerned, whereas for women of 50 years of age or older the receptor status is of great prognostic relevance. Besides the lymph node status, the proliferation index shows in a Cox regression model the greatest prognostic importance for the further course of a primary carcinoma of the breast.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

[Prognostic significance of cell kinetic parameters of endometrial cancer].

In 120 patients suffering from carcinoma of the endometrium of a wide variety of histological types, conventional clinical and morphological criteria of prognosis were compared with the DNA index (DI) and the S-phase fraction. The cellular kinetics parameters were obtained via flow cytophotometry. Adenocarcinomas (n = 101) were more frequently DNA diploid and had a lower S-phase share (less than 5%) than adenoacanthomas, clear-cell carcinomas and malignant Müller's mixed tumors. There are close correlations between the conventional prognostic factors such as FIGO stage, relative tumor invasion depth, grading and oestrogen or progesteron receptor content and the DNA content or S-phase fraction. Carcinomas with a DI less than or equal to 1.1 (n = 83) and the S-phase fraction less than 5% (n = 77), have a significantly longer survival time and recurrence-free interval than DNA-aneuploid tumors with a high S-phase fraction. The studies underline the need to use flow cytophotometry in the prognostic assessment of the carcinoma of the endometrium. The method is superior to histological grading, since the results obtained can be objectively assessed.

Aged↗