Evidence map›Paper›PMID 23169334›Full record

ArticleBritish journal of cancer2012

Smaller sample sizes for phase II trials based on exact tests with actual error rates by trading-off their nominal levels of significance and power.

I Khan, S-J Sarker, A Hackshaw

Registry-linked trialAbstract read
In one paragraph

Article in British journal of cancer, 2012. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT04802707 (A Phase II, Monocenter, Single Arm Study To Assess The Safety and Efficacy Of Combination Deoxycytidine and Deoxythymidine For Mitochondrial Depletion Disorders), which is not on this map. Cited by 21 papers.

0numbers the graph read from it
0cells of the map it votes in
21citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT04802707 phase2recruitingnot on this mapstarted 2021, after this paper: background citation

A Phase II, Monocenter, Single Arm Study To Assess The Safety and Efficacy Of Combination Deoxycytidine and Deoxythymidine For Mitochondrial Depletion Disorders

TypeinterventionalSponsorKenneth Myers, MDRan2021 to 2029Enrolled200ConditionsMitochondrial Diseases, Mitochondrial Encephalomyopathy, Mitochondrial Encephalopathy, Mitochondrial DNA DepletionArmsdeoxycytidine and deoxythymidine
3 · Its place in the literature

Who cites it

21 citing papers in PubMed.

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  6. Reply.Arthritis & rheumatology (Hoboken, N.J.) · 2026
    Article
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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

3 authors.

I KhanCancer Research UK and UCL Cancer Trials Centre, University College London, 90 Tottenham Court Road (fifth floor), London, UK. I.Khan@ucl.ac.uk
S-J Sarker
A Hackshaw

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundSample sizes for single-stage phase II clinical trials in the literature are often based on exact (binomial) tests with levels of significance (alpha (α) <5% and power >80%). This is because there is not always a sample size where α and power are exactly equal to 5% and 80%, respectively. Consequently, the opportunity to trade-off small amounts of α and power for savings in sample sizes may be lost.

methodsSample-size tables are presented for single-stage phase II trials based on exact tests with actual levels of significance and power. Trade-off in small amounts of α and power allows the researcher to select from several possible designs with potentially smaller sample sizes compared with existing approaches. We provide SAS macro coding and an R function, which for a given treatment difference, allow researchers to examine all possible sample sizes for specified differences are provided.

resultsIn a single-arm study with P(0) (standard treatment)=10% and P(1) (new treatment)=20%, and specified α=5% and power=80%, the A'Hern approach yields n=78 (exact α=4.53%, power=80.81%). However, by relaxing α to 5.67% and power to 77.7%, a sample size of 65 can be used (a saving of 13 patients).

interpretationThe approach we describe is especially useful for trials in rare disorders, or for proof-of-concept studies, where it is important to minimise the trial duration and financial costs, particularly in single-arm cancer trials commonly associated with expensive treatment options.

Indexed as

Clinical Trials, Phase II as TopicResearch DesignSample SizeHumansNeoplasmsRandomized Controlled Trials as Topic

Identifiers

PMID23169334
PMCPMC3504941

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Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.