R Ng1, G R Pond, P A Tang, P W MacIntosh, L L Siu, E X Chen. 1. Department of Medical Oncology and Hematology, Princess Margaret Hospital, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada.
Abstract
BACKGROUND: Although disease-free survival (DFS) is accepted as a valid end point in adjuvant breast cancer trials, improvement in 2-year DFS has never been formally established as an adequate correlate for 5-year overall survival (OS). We set out to ascertain if changes in 2-year DFS can be used to accurately predict 5-year OS changes. DESIGN: We conducted a systematic Medline search (1966-2006) for randomized adjuvant breast cancer trials of >100 patients per arm with 2-year DFS and 5-year OS data. A univariate regression model weighted by trial sample size was constructed to determine whether 2-year DFS differences between treatment arms within trials were predictive of 5-year OS differences. RESULTS: A total of 126 studies containing 149 treatment comparisons met the inclusion criteria. Difference in 2-year DFS was a significant predictor of difference in 5-year OS. For every 1% increase in 2-year DFS difference, the 5-year OS difference increased by 0.5%-0.55%. The proportion of variation explained ranged from 0.38 to 0.42, with a wide prediction interval. CONCLUSION: There is a statistically significant correlation, of moderate strength, between difference in 2-year DFS between treatment comparisons and difference in 5-year OS but the correlation is not strong enough to be used as a predictor.
BACKGROUND: Although disease-free survival (DFS) is accepted as a valid end point in adjuvant breast cancer trials, improvement in 2-year DFS has never been formally established as an adequate correlate for 5-year overall survival (OS). We set out to ascertain if changes in 2-year DFS can be used to accurately predict 5-year OS changes. DESIGN: We conducted a systematic Medline search (1966-2006) for randomized adjuvant breast cancer trials of >100 patients per arm with 2-year DFS and 5-year OS data. A univariate regression model weighted by trial sample size was constructed to determine whether 2-year DFS differences between treatment arms within trials were predictive of 5-year OS differences. RESULTS: A total of 126 studies containing 149 treatment comparisons met the inclusion criteria. Difference in 2-year DFS was a significant predictor of difference in 5-year OS. For every 1% increase in 2-year DFS difference, the 5-year OS difference increased by 0.5%-0.55%. The proportion of variation explained ranged from 0.38 to 0.42, with a wide prediction interval. CONCLUSION: There is a statistically significant correlation, of moderate strength, between difference in 2-year DFS between treatment comparisons and difference in 5-year OS but the correlation is not strong enough to be used as a predictor.
Authors: Ava Kwong; L P Wong; H N Wong; F B F Law; E K O Ng; Y H Tang; W K Chan; D T K Suen; C Choi; L S Ho; K H Kwan; M Poon; T T Wong; K Chan; S W W Chan; M W L Ying; W C Chan; E S K Ma; J M Ford; D W West Journal: Hugo J Date: 2010-04-10