BUYSE, M & RYAN, LM 1987, 'ISSUES OF EFFICIENCY IN COMBINING PROPORTIONS OF DEATHS FROM SEVERAL CLINICAL-TRIALS', STATISTICS IN MEDICINE, vol. 6, no. 5, pp. 565-576.
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The Mantel–Haenszel test provides a straightforward method to combine results from several clinical trials when only summary information, such as the proportion of deaths, is available for each trial. More efficient tests, such as the stratified logrank test, should be used if the survival and censoring times are known for all individuals, but in practice, the cost and effort of obtaining this information may be prohibitive. The purpose of this paper is to derive a general expression for the asymptotic relative efficiency (ARE) of the Mantel–Haenszel test with respect to the stratified logrank test, and to compute the ARE in situations which are likely to be of practical interest. The results show that under realistic assumptions about the survival distribution, losses to follow‐up and duration of accrual, the ARE frequently exceeds 80 per cent. An example is given to show the usefulness of the approach when combining proportions of deaths from several cancer clinical trials. Copyright © 1987 John Wiley & Sons, Ltd.
CNAAN, A & RYAN, L 1987, 'ANALYZING SURVIVAL FROM INITIAL DIAGNOSIS', CONTROLLED CLINICAL TRIALS, vol. 8, no. 3, pp. 283-283.
FALKSON, G, RYAN, LM, JOHNSON, LA, SIMSON, IW, COETZER, BJ, CARBONE, PP, CREECH, RH & SCHUTT, AJ 1987, 'A RANDOM PHASE-II STUDY OF MITOXANTRONE AND CISPLATIN IN PATIENTS WITH HEPATOCELLULAR-CARCINOMA - AN ECOG STUDY', CANCER, vol. 60, no. 9, pp. 2141-2145.
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Of 86 patients entered in an Eastern Cooperative Oncology Group (ECOG) random Phase II study of mitoxantrone (DHAD) and cisplatin (DDP) in primary liver cancer, 69 were eligible. Nine of the 13 ineligible patients were excluded after a pathology review. Sixty‐one percent of the patients were North American, and 39% were South African. The most common severe or the worst toxicity on DHAD was hematologic; and to DDP, hematologic and vomiting. Of the 69 eligible patients, 21 experienced severe, life‐threatening or fatal toxic reactions. Two patients treated with DDP had partial responses. With a 95% confidence interval, the true response rate to DHAD was less than 8%, and to DDP, less than 17%. The median survival time was 14 weeks on both drugs. Assuming a proportional hazards model, factors that are significantly associated with survival are patient performance status, the presence of the symptoms, raised bilirubin and hepatomegaly, and clinical evidence of cirrhosis. Any differences between survival rates for South African and North American patients were largely explainable by these factors. Copyright © 1987 American Cancer Society
FINKELSTEIN, DM & RYAN, LM 1987, 'ESTIMATING CARCINOGENIC POTENCY FROM A RODENT TUMORIGENICITY EXPERIMENT', APPLIED STATISTICS-JOURNAL OF THE ROYAL STATISTICAL SOCIETY SERIES C, vol. 36, no. 2, pp. 121-133.
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Rodent tumorigenicity experiments are conducted to determine whether a particular substance accelerates tumour development. The association between exposure to this substance and the risk of tumour development can be characterized by a measure of carcinogenic potency. The most commonly used potency measure, the dose effect on the lifetime risk of tumour, may be seriously biased, especially when control and exposed groups differ with respect to longevity. However, more appropriate measures, which account for age at death, are largely unavailable except in the special cases of instantly lethal or nonlethal tumours or tumours with observable onset. In this paper, we propose an estimate of carcinogenic potency based on a proportonal prevalence odds model which applies regardless of tumour lethality and can be calculated using standard statistical methodologies. Furthermore, we show how our estimator can be used to generalize available potency estimators to tumours of any lethalit