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The choice of test in phase II cancer trials assessing continuous tumour shrinkage when complete responses are expected

Lookup NU author(s): Professor James WasonORCiD



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


© SAGE Publications. Traditionally, phase II cancer trials test a binary endpoint formed from a dichotomisation of the continuous change in tumour size. Directly testing the continuous endpoint provides considerable gains in power, although also results in several statistical issues. One such issue is when complete responses, i.e. complete tumour removal, are observed in multiple patients; this is a problem when normality is assumed. Using simulated data and a recently published phase II trial, we investigate how the choice of test affects the operating characteristics of the trial. We propose using parametric tests based on the censored normal distribution, comparing them to the t-test and Wilcoxon non-parametric test. The censored normal distribution fits the real dataset well, but simulations indicate its type-I error rate is inflated, and its power is only slightly higher than the t-test. The Wilcoxon test has deflated type I error. For two-arm designs, the differences are much smaller. We conclude that the t-test is suitable for use when complete responses are present, although positively skewed data can result in the non-parametric test having higher power.

Publication metadata

Author(s): Wason JMS, Mander AP

Publication type: Article

Publication status: Published

Journal: Statistical Methods in Medical Research

Year: 2015

Volume: 24

Issue: 6

Pages: 909-919

Print publication date: 01/12/2015

Online publication date: 16/12/2011

Acceptance date: 01/01/1900

Date deposited: 26/01/2018

ISSN (print): 0962-2802

ISSN (electronic): 1477-0334

Publisher: SAGE Publications Ltd


DOI: 10.1177/0962280211432192

PubMed id: 22179821


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