Colin B. Begg

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An adjusted rank correlation test is proposed as a technique for identifying publication bias in a meta-analysis, and its operating characteristics are evaluated via simulations. The test statistic is a direct statistical analogue of the popular "funnel-graph." The number of component studies in the meta-analysis, the nature of the selection mechanism, the(More)
In the assessment of the statistical properties of a diagnostic test, for example the sensitivity and specificity of the test, it is common to derive estimates from a sample limited to those cases for whom subsequent definitive disease verification is obtained. Omission of nonverified cases can seriously bias the estimates. In order to adjust the estimates(More)
PURPOSE Several single-institution phase II trials have reported that the Dartmouth regimen (dacarbazine, cisplatin, carmustine, and tamoxifen) can induce major tumor responses in 40% to 50% of stage IV melanoma patients. This study was designed to compare the overall survival time, rate of objective tumor response, and toxicity of the Dartmouth regimen(More)
CONTEXT Hospitals that treat a relatively high volume of patients for selected surgical oncology procedures report lower surgical in-hospital mortality rates than hospitals with a low volume of the procedures, but the reports do not take into account length of stay or adjust for case mix. OBJECTIVE To determine whether hospital volume was inversely(More)
The prognostic effect of weight loss prior to chemotherapy was analyzed using data from 3,047 patients enrolled in 12 chemotherapy protocols of the Eastern Cooperative Oncology Group. The frequency of weight loss ranged from 31 percent for favorable non-Hodgkin's lymphoma to 87 percent in gastric cancer. Median survival was significantly shorter in nine(More)
BACKGROUND Randomized trials have established that 5-fluorouracil-based adjuvant chemotherapy following resection of stage III colon cancer reduces subsequent mortality by as much as 30%. However, the extent to which adjuvant therapy is used outside the clinical trial setting, particularly among the elderly, is unknown. METHODS A retrospective cohort(More)
PURPOSE Cancer at the resection margin (a positive surgical margin) after radical prostatectomy is associated with an increased risk of recurrence even after adjusting for other known risk factors, including pretreatment serum prostate specific antigen (PSA), clinical stage, grade and pathological stage (level of extracapsular extension, seminal vesicle(More)
BACKGROUND Although there is no proven benefit associated with screening for lung cancer, screening programs are attracting many individuals who perceive themselves to be at high risk due to smoking. We sought to determine whether the risk of lung cancer varies predictably among smokers. METHODS We used data on 18 172 subjects enrolled in the Carotene and(More)
PURPOSE Women with breast cancer diagnosed early in life comprise a substantial portion of those tested for BRCA1/BRCA2 mutations; however, little information is available on the subsequent risks of contralateral breast cancer in mutation carriers. This study assessed the risk of subsequent contralateral breast cancer associated with carrying a BRCA1 or(More)
CONTEXT The risk of breast cancer in BRCA1 and BRCA2 mutation carriers has been examined in many studies, but relatively little attention has been paid to the degree to which the risk may vary among carriers. OBJECTIVES To determine the extent to which risks for BRCA1 and BRCA2 carriers vary with respect to observable and unobservable characteristics. (More)