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. 2015 Jul 27;10(7):e0132853.
doi: 10.1371/journal.pone.0132853. eCollection 2015.

Impact of Adjuvant Chemotherapy on Breast Cancer Survival: A Real-World Population

Lea Rossi  1 , Denise Stevens  2 , Jean-Yves Pierga  2 , Florence Lerebours  2 , Fabien Reyal  2 , Mathieu Robain  2 , Bernard Asselain  2 , Roman Rouzier  1
Affiliations

Impact of Adjuvant Chemotherapy on Breast Cancer Survival: A Real-World Population

Lea Rossi et al. PLoS One. .

Abstract

Background: The impact of adjuvant chemotherapy on breast cancer prognosis has been demonstrated in randomized trials, but its impact is unknown in real-world populations. The aim of this study was to evaluate the effect of adjuvant chemotherapy on the survival of breast cancer patients in an unselected population.

Methods: This prospective cohort study included 32,502 women treated at the Institut Curie between 1981 and 2008 for a first invasive breast cancer without metastasis. The patients were matched based on their propensity score to receive adjuvant chemotherapy.

Results: The matching generated a subsample of 9,180 patients with an overlapping propensity score. In the group without chemotherapy, the overall survival (OS) rates at 5 and 10 years of follow-up were 87.6% (95% CI [86.7-88.6]) and 75.0% (95% CI [73.6-76.5]), respectively, versus 92.1% (95% CI [91.3-92.9]) and 81.9% (95% CI [80.6-83.2]), respectively, in the chemotherapy group. Distant disease-free survival (DDFS) was significantly improved in the five first years (absolute benefit of 3.5%). In a multivariate analysis, adjuvant chemotherapy was associated with better OS (HR = 0.75, 95% CI [0.69-0.83], p<0.0001) and DDFS (HR = 0.82, 95% CI [0.75-0.90], p<0.0001).

Conclusion: Adjuvant chemotherapy significantly improves OS and DDFS rates in an unselected population, in accordance with previous results reported by randomized trials.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Distribution of propensity scores prior to and after matching.
Mean propensity score (PS) before matching was 0.69 (SD = 0.20) in the chemotherapy-treated group and 0.28 (SD = 0.20) in the non-treated group (p<0.0001). After matching, it was 0.43 (SD = 0.25) in the chemotherapy-treated group and 0.42 (SD = 0.25) in the non-treated group (p = 0.22).
Fig 2
Fig 2. Overall survival (OS) and distant disease-free survival (DDFS) according to adjuvant chemotherapy prior to and after matching via propensity scores.
HR: hazard ratio.
See this image and copyright information in PMC

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