title: Predictors of the risk of fibrosis at 10 years after breast conserving therapy for early breast cancer: a study based on the EORTC Trial 22881-10882 'boost versus no boost'.
abstract: The EORTC 22881-10882 trial in 5178 conservatively treated early breast cancer patients showed that a 16 Gy boost dose significantly improved local control, but increased the risk of breast fibrosis. To investigate predictors for the long-term risk of fibrosis, Cox regression models of the time to moderate or severe fibrosis were developed on a random set of 1797 patients with and 1827 patients without a boost, and validated in the remaining set. The median follow-up was 10.7 years. The risk of fibrosis significantly increased (P<0.01) with increasing maximum whole breast irradiation (WBI) dose and with concomitant chemotherapy, but was independent of age. In the boost arm, the risk further increased (P<0.01) if patients had post-operative breast oedema or haematoma, but it decreased (P<0.01) if WBI was given with >6 MV photons. The c-index was around 0.62. Nomograms with these factors are proposed to forecast the long-term risk of moderate or severe fibrosis.
authors.affiliation: Statistics Department, EORTC Headquarters, Brussels, Belgium. sandra.collette@eortc.be
authors.forename: Sandra
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authors.lastname: Collette
authors.forename: Laurence
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authors.lastname: Collette
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authors.forename: Jean-Claude
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authors.lastname: Morgan
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authors.lastname: Salamon
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authors.lastname: Mirimanoff
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authors.lastname: Bolla
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authors.lastname: Van der Hulst
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authors.lastname: Wárlám-Rodenhuis
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