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Generalizability of cancer clinical trial results
Author(s) -
Elting Linda S.,
Cooksley Catherine,
Bekele B. Nebiyou,
Frumovitz Michael,
Avritscher Elenir B. C.,
Sun Charlotte,
Bodurka Diane C.
Publication year - 2006
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/cncr.21907
Subject(s) - generalizability theory , medicine , clinical trial , population , cancer , cohort , comparability , epidemiology , proportional hazards model , retrospective cohort study , oncology , demography , environmental health , statistics , mathematics , combinatorics , sociology
BACKGROUND The generalizability of clinical trial results is questionable, because fewer than 5% of cancer patients participate. The authors examined the comparability of clinical trial participants and nonparticipants and the potential impact of differences. METHODS A retrospective cohort of 19,340 cancer patients who were diagnosed between January 1990 and December 1997 was characterized by trial participation. The distributions of prognostically important factors among trial participants were compared with the distributions among nonparticipants and the population of patients diagnosed during the same period in the Surveillance, Epidemiology, and End Results population. The impact of these factors on survival was examined by using a Cox proportional hazards analysis. RESULTS Trial participants were younger and had better performance status and fewer comorbid conditions compared with nonparticipants. However, participants were more likely to have locally advanced disease, positive lymph node status, poorly differentiated tumors, liver metastases, and multiple metastatic sites. The former factors were associated with significantly longer survival, whereas the later factors were associated with significantly shorter survival. CONCLUSIONS The lack of comparability between trial participants and nonparticipants called into question the generalizability of clinical trial results. Although selective recruitment for clinical trials is justified, the authors encourage the use of population‐based trials of effectiveness in “all comers.” Cancer 2006. © 2006 American Cancer Society.