Devita, Hellman, and Rosenberg's Cancer

LWBK1006-16 LWW-Govindan-Review December 12, 2011 18:55

188 DeVita, Hellman, and Rosenberg’s CANCER: Principles and Practice of Oncology Review

Question 16.18. The intention-to-treat analysis is considered the primary analysis of data

from a clinical trial. Which of the following describes an intention-to-treat

analysis?

A. An ineligible patient is not included in an intention-to-treat analysis

because the study treatment is not appropriate for that patient.

B. All patients who give consent and are randomized are included in

the intention-to-treat analysis in the study arm to which they were

randomized.

C. Data from patients who are ineligible or who die or withdraw from

the study before completion should be analyzed separately from data

from eligible patients who complete the trial.

D. Lack of compliance can distort the results from patients who fail to

complete the trial, so these data should be dropped from an intention-

to-treat analysis.

Question 16.19. An interim analysis is any assessment of data performed during patient

enrollment or follow-up period of a trial. Which of the following is NOT

true for planning clinical trials with interim analyses?

A. Multiple looks at outcome data over the course of a trial will alter

type I and II errors. Unless they are included in the design, multiple

looks will cause the operating characteristics of the trial to deviate

from the planned values.

B. Various group-sequential designs have been proposed to guide the

statistical significance testing of a fixed number of interim analyses

that are usually specified from the outset.

C. The method of stochastic curtailment is designed to calculate condi-

tional power (the projected probability of rejecting the null hypothesis

at the end of study), conditional on the accumulated information, and

to stop the trial if the conditional power is small (e.g., 0.2). In such a

“futility” analysis, the number of interim analyses does not need to

be fixed in advance.

D. A data-safety committee is usually put in charge of the interpretation

of interim analyses. The committee also includes the study leaders to

notify the patients and medical community in a timely manner.