Breast density change as a predictive surrogate for response to adjuvant endocrine therapy in hormone receptor positive breast cancer
A partir de données portant sur 1 065 patientes atteintes d'un cancer du sein ER+ traité par chirurgie entre 2003 et 2006 (durée médiane de suivi : 68,8 mois), cette étude évalue l'association entre l'évolution à court terme de la densité mammaire et la réponse à un traitement adjuvant par tamoxifène ou inhibiteurs d'aromatase
INTRODUCTION:Anti-estrogen therapy has been shown to reduce mammographic breast density (MD). We hypothesized that a short-term change in breast density may be a surrogate biomarker predicting response to adjuvant endocrine therapy (ET) in breast cancer.METHODS:We analyzed data for 1,065 estrogen receptor (ER)-positive breast cancer patients who underwent surgery between 2003 and 2006 and received at least 2 years of ET, including tamoxifen and aromatase inhibitors. MD was measured using Cumulus software 4.0 and expressed as a percentage. MD reduction (MDR) was defined as the absolute difference in MD of mammograms taken preoperatively and 8-20 months after the start of ET.RESULTS:At a median follow-up of 68.8 months, the overall breast cancer recurrence rate was 7.5% (80/1065). Mean MDR was 5.9% (range, -17.2% to 36.9%). Logistic regression analysis showed that age <50 years, high preoperative MD, and long interval between start of ET to follow-up mammogram were significantly associated with larger MDR (p<0.05). In a survival analysis, tumor size, lymph node positivity, high Ki-67 ([greater than or equal to]10%), and low MDR were independent factors significantly associated with recurrence-free survival (p<0.05). Compared with the group showing the greatest MDR ([greater than or equal to]10%), the hazard ratios for MDRs of 5-10%, 0-5%, and <0% were 1.33, 1.92, and 2.26, respectively.CONCLUSIONS:MD change during short-term use of adjuvant ET was a significant predictor of long-term recurrence in women with ER-positive breast cancer. Effective treatment strategies are urgently needed in patients with low MDR despite about 1 year of ET.
Breast Cancer Research , article en libre accès, 2011