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Biomedical subjects

S Wieand

Publications and source records attributed to S Wieand.

10 recordsLinked to original sources
PubMed1997

Effect of preoperative chemotherapy on local-regional disease in women with operable breast cancer: findings from National Surgical Adjuvant Breast and Bowel Project B-18.

PURPOSE: To determine whether preoperative doxorubicin and cyclophosphamide (AC) permits more lumpectomies to be performed and decreases the incidence of positive nodes in women with primary breast cancer. PATIENTS AND METHODS: Women (n = 1,523) were randomized to National Surgical Adjuvant Breast and Bowel Project (NSABP) B-18; 759 eligible patients received postoperative AC and 747, preoperative AC. The clinical size of breast and axillary tumors was determined before each of four cycles of AC and before surgery. Tumor response to preoperative therapy was clinically complete (cCR), partial (cPR), stable (cSD), or progressive disease (cPD). Tissue from patients with a cCR was evaluated for a pathologic complete response (pCR). RESULTS: Breast tumor size was reduced in 80% of patients after preoperative therapy; 36% had a cCR. Tumor size and clinical nodal status were independent predictors of cCR. Twenty-six percent of women with a cCR had a pCR. Clinical nodal response occurred in 89% of node-positive patients: 73% had a cCR and 44% of those had a pCR. There was a 37% increase in the incidence of pathologically negative nodes. Before randomization, lumpectomy was proposed for 86% of women with tumors < or = 2 cm, 70% with tumors 2.1 to 5.0 cm, and 3% with tumors > or = 5.1 cm. Clinical tumor size and nodal status influenced the physician's decision. Overall, 12% more lumpectomies were performed in the preoperative group; in women with tumors > or = 5.1 cm, there was a 175% increase. CONCLUSION: Preoperative therapy reduced the size of most breast tumors and decreased the incidence of positive nodes. The greatest increase in lumpectomy after preoperative therapy occurred in women with tumors > or = 5 cm, since women with tumors less than 5 cm were already lumpectomy candidates. Preoperative therapy should be considered for the initial management of breast tumors judged too large for lumpectomy.

Antibiotics, Antineoplastic↗
PubMed1995

A statistic for comparing two correlated markers which are prognostic for time to an event.

A proliferation of biologic markers has led to increased interest in methods for comparing the prognostic value of markers in predicting time to recurrence of or death from disease. This paper proposes a nonparametric test statistic for comparing two continuous markers when the outcome of interest is time to an event and the outcome is subject to right censoring. Results from Monte Carlo studies show that the new testing procedure is reliable for practical use. We present an example in which we use the statistic successfully in a colon cancer study to select between two potentially useful markers.

Adenocarcinoma↗
PubMed1992

Description of the statistical aspects of a study for advanced colorectal cancer patients.

A screening design was used in a trial that compared a standard regimen to five experimental regimens for the treatment of advanced colorectal cancer where the endpoint was survival. The two-stage design permitted the termination of accrual to experimental regimens that failed to show promise at the first stage. It also allowed for termination of accrual to the standard regimen if an experimental regimen appeared to offer a highly significant improvement over the standard regimen. This paper presents a description of the design and the results of the trial.

Bayes Theorem↗
PubMed1988

A design for phase II testing of anticancer agents within a phase III clinical trial.

A design for testing new anticancer agents is proposed such that the initial testing of new agents (phase II trials) is included within the framework of a comparative clinical trial (phase III). Randomization between phase II trials and the treatment groups of the phase III trial enforces consistency of patient selection and evaluation of response criteria. Patients who progress on the phase II trials of the new agents are randomized to one of the treatments of the phase III trial. Design issues, such as sample size and power, and analysis of the proposed design, are discussed. Advantages and disadvantages of the design are illustrated by sample size calculations for a current clinical trial in advanced breast cancer.

Antineoplastic Agents↗
PubMed1987

A two-stage design for randomized trials with binary outcomes.

A two-stage rule for a randomized clinical trial with a dichotomous outcome is presented. It is based on a rule discussed by Ellenberg and Eisenberger (Cancer Treat Rep 69:1147-1154, 1985). The rule is shown to lead to a reduction in expected sample size if the test treatment is ineffective, with almost no loss in power. All the mathematical formulas required to design such a rule are given, as well as some time-saving approximations. The accuracy of the approximations is shown.

Clinical Trials as Topic↗
PubMed1983

A prospective evaluation and follow-up of patients with syncope.

We prospectively evaluated and followed 204 patients with syncope to determine how often a cause of syncope could be established and to define the prognosis of such patients. A cardiovascular cause was established in 53 patients and a noncardiovascular cause in 54. The cause remained unknown in 97 patients. At 12 months, the overall mortality was 14 +/- 2.5 per cent. The mortality rate (30 +/- 6.7 per cent) in patients with a cardiovascular cause of syncope was significantly higher than the rate (12 +/- 4.4 per cent) in patients with a noncardiovascular cause (P = 0.02) and the rate (6.4 +/- 2.8 per cent) in patients with syncope of unknown origin (P less than 0.0001). The incidence of sudden death was 24 +/- 6.6 per cent in patients with a cardiovascular cause, as compared with 4 +/- 2.7 per cent in patients with a noncardiovascular cause (P = 0.005) and 3 +/- 1.8 per cent in patients with syncope of unknown origin (P = 0.0002). Patients with syncope can be separated into diagnostic categories that have prognostic importance. Patients with a cardiovascular cause have a strikingly higher incidence of sudden death than patients with a noncardiovascular or unknown cause.

Adolescent↗
PubMedDate not supplied

Stopping when the experimental regimen does not appear to help.

We discuss a procedure that offers the possibility of reducing the number of patients assigned to experimental regimens which are no more effective than a standard regimen. The procedure is useful in advanced cancer trials in which the length of the accrual period might be more than twice the median survival time for the standard regimen. The procedure is intuitively appealing and offers a 50 per cent chance of stopping accrual to ineffective therapies, yet is associated with a loss of power of less than 0.02.

Antineoplastic Combined Chemotherapy Protocols↗