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Biomedical subjects

N Breslow

Publications and source records attributed to N Breslow.

At least 55 records · Page 3Linked to original sources
PubMed1985

On the prevalence and roles of females in the sadomasochistic subculture: report of an empirical study.

The existence of females in the sadomasochistic subculture has generally been denied in the theoretical, clinical, and empirical literature. The assumption that females do not exist in the subculture, or exist in such small numbers as to make analysis impossible, was tested. Questionnaires were placed in two publications that cater to sadomasochists, and additional questionnaires were mailed to advertisers whose ads appeared in a sadomasochistic contact magazine. Of 182 individuals who responded, 130 were males, and 52 were females, indicating a meaningful female presence in the subculture. An analysis of the replies revealed similarities and differences between the male and female respondents.

Adult↗
PubMed1985

Prognosis for Wilms' tumor patients with nonmetastatic disease at diagnosis--results of the second National Wilms' Tumor Study.

Multivariate statistical methods were used to study prognosis for 632 patients entered on the second National Wilms' Tumor Study who had nonmetastatic, unilateral disease at diagnosis. Separate analyses were conducted for each of four endpoints: abdominal recurrence, distant metastasis, relapse without regard to site, and death. The two most important predictors for metastasis and general relapse were an unfavorable (anaplastic or sarcomatous) histology and the presence of microscopically confirmed disease in the regional lymph nodes. Operative spillage of tumor increased the rates of abdominal recurrence and death, even after accounting for histology and lymph node effects. The presence of a tumor thrombus in the renal vein or IVC increased the risk of metastasis, and intrarenal vascular invasion was associated with general relapse after accounting for histology, lymph nodes, and spillage. However, these latter associations were weaker, and some uncertainty remains regarding the true prognostic import of such findings due to a high degree of collinearity among variables. By contrast to the results of a similar data analysis for the first National Wilms' Tumor Study, specimen weight had no bearing on outcome, and the effects of age at diagnosis were entirely explained by the association of age with other more critical factors.

Adolescent↗
PubMed1985

Multivariate cohort analysis.

Modern methods of categorical and survival data analysis are usefully applied to the multivariate analysis of follow-up data that arise in epidemiologic cohort studies. They provide a formal basis for extending analyses based on the standardized mortality ratio into the multivariate domain so as to permit simultaneous consideration of such risk factors as age, duration, and intensity of exposure; age and calendar year of follow-up; and personal characteristics. Analogous methods are available that control for demographic variables internally, without reference to vital statistics or other standard rates. Various model structures allow for the effects of different variables to combine in an additive, multiplicative, or mixed (additive relative risks) fashion. Illustrative analyses are provided of the relationship between respiratory cancer mortality and arsenic exposure in a cohort of Montana smelter workers.

Arsenic↗
PubMed1982

Metachronous bilateral Wilms' tumor, National Wilms' Tumor Study.

Eighteen of the patients randomized for treatment according to the first and second National Wilms' Tumor Studies have developed clinically evident tumor in the contralateral kidney subsequent to the initial diagnosis. Only seven of 18 had an adequate exploration of the opposite kidney during the initial surgery and of these seven, four had abnormal findings. Thirteen of 18 cases showed some form of nephroblastomatosis histologically. The original tumors in six and possibly seven were multicentric in origin. While metachronous Wilms' tumors are an unusual occurrence, the prognosis is ominous with only seven of 18 surviving free of disease. The outlook might be improved with adequate attention to the surgical and histologic details during the initial diagnostic procedures.

Child, Preschool↗
PubMed1982

Covariance adjustment of relative-risk estimates in matched studies.

The matched-sample case-control study is widely used by epidemiologists to estimate the relative incidence of disease among persons exposed to different levels of one or more risk factors. An apparent limitation of such designs has been the necessity to control the effects of all potential confounding variables in the matching process. Conditional likelihood analyses based on the linear logistic equation enable one to model the effects of covariates while preserving the original matching. This paper reviews the logical basis for this methodology and illustrates its value by application to a case-control study of esophageal cancer.

Analysis of Variance↗
PubMed1981

The treatment of Wilms' tumor: results of the Second National Wilms' Tumor Study.

One-hundred-eighty-eight children up to 16 years of age were randomized in the second National Wilms' Tumor Study (NWTS) with tumors that were confined to the kidney and that had been totally excised (Group I). Most fared well whether treated for six or for 15 months with both actinomycin D (AMD) and vincristine (VCR). No postoperative radiation therapy (RT) was given. The two-year relapse-free survival (RFS) and two-year survival rates were 88 and 95%, respectively. Two-hundred-sixty-eight randomized patients with more advanced local lesions (Groups II and III) and 57 with distant metastases (Group IV) had postoperative RT and were scheduled for 15 months treatment with either AMD and VCR (Reg. C) or AMD plus VCR plus Adriamycin (Reg. D). The 77% two-year RFS rate for Reg. D was significantly different from the 63% with Reg. C. As in the first NWTS, patients with tumors of unfavorable histology (UH) had a significantly worse prognosis than those with favorable histology (FH), as did those with positive nodes. Survival rates at two years were 54% for UH vs. 90% for FH, and 54% vs. 82% for those with and without lymph node involvement.

Adolescent↗
PubMed1981

Retrospective validation of a new staging system for Wilms' tumor.

Prognostic significance has been ascribed to certain clinicopathological features of the Wilms' tumor. Examples are size, vascular invasion, histologic characteristics, tumor rupture, and lymph nodal involvement. Several of these were arranged into a grouping system, and used in a cooperative clinical trial, the first National Wilms' Tumor Study (NWTS). Detailed clinicopathologic information was accumulated for each patient entered in the study, and these data were analyzed with respect to their prognostic import. Factors found to be of significance were rearranged into a proposed staging system, believed more likely to be predictive of outcome for patients with tumor spread beyond the kidney confines, but without distant metastases (Groups II and III). The postulated discriminatory superiority was tested using Group II and III patients entered in the second NWTS. The same children were reassigned retrospectively to Stages II and III, and the outcomes compared. Statistically significant differences were noted between Stages II and III, but not for Groups II and III. These results encourage the use of the new staging system in the third NWTS.

Humans↗
PubMed1980

Results of the National Wilms' Tumor Study: Treatment response in misclassified patients.

This report evaluates the outcome in patients treated in accord with protocol requirements of the National Wilms' Tumor Study who were assigned incorrectly to any of several clinical groups because of mistaken initial assessments of the extent of disease. A significant difference in response was found between patients correctly staged Group I and those of higher stages incorrectly placed in Group I. This observation emphasizes the need for careful staging, and for "upstaging" in doubtful Group I patients.

Child↗
PubMed1979

Statistical methods for censored survival data.

Methods of statistical analysis of censored survival times are briefly reviewed and illustrated by application to clinical trials data. These include estimation of the survival curce, nonparametric tests to compare several survival curves, tests for trend, and regression analysis. Extensions of the methodology are made for application to epidemiologic case-control studies. These are used to estimate relative risks for leukemia associated with radiation exposures. A final section provides some annotated references to the recent literature.

Clinical Trials as Topic↗
PubMed1978

Perspectives on the statistician's role in cooperative clinical research.

Some contributions which the statistician can make to cooperative research are briefly discussed in the hope of furthering communication between statistician and clinician. In the planning stages the major issues are those of sample size, randomization, data collection and early termination. Careful consideration of these points can help ensure that the main questions posed by the trial are answered as economically as possible. During the final stages the major statistical contribution is in analysis and presentation of results in a way which explores the interrelationships between the most important baseline and therapeutic factors and their joint effect on outcome.

Clinical Trials as Topic↗
PubMed1978

Are there two logistic regressions for retrospective studies?

A comparison is made between two different approaches to the linear logistic regression analysis of retrospective study data: the prospective model wherein the dependent variable is a dichotomous indicator of case/control status; and the retrospective model wherein the dependent variable is a binary or polychotomous classification of exposure. The two models yield increasingly similar estimates of the relative risk with increasing degrees of covariate adjustment. When the covariate effects are saturated with parameters, the relative risk estimates are identical. The prospective model is generally to be preferred for studies involving multiple quantitative risk factors.

Child↗