Effect of obesity on prognosis after early-stage breast cancer.

PURPOSE: This study was performed to characterize the impact of obesity on the risk of breast cancer recurrence and death as a result of breast cancer or other causes in relation to adjuvant treatment. PATIENTS AND METHODS: Information on body mass index (BMI) at diagnosis was available for 18,967 (35%) of 53,816 women treated for early-stage breast cancer in Denmark between 1977 and 2006 with complete follow-up for first events (locoregional recurrences and distant metastases) up to 10 years and for death up to 30 years. Information was available on prognostic factors and adjuvant treatment for all patients. Univariate analyses were used to compare the associations of known prognostic factors and risks of recurrence or death according to BMI categories. Cox proportional hazards regression models were used to assess the influence of BMI after adjusting for other factors. RESULTS: Patients with a BMI of 30 kg/m(2) or more were older and had more advanced disease at diagnosis compared with patients with a BMI below 25 kg/m(2) (P < .001). When data were adjusted for disease characteristics, the risk of developing distant metastases after 10 years was significantly increased by 46%, and the risk of dying as a result of breast cancer after 30 years was significantly increased by 38% for patients with a BMI of 30 kg/m(2) or more. BMI had no influence on the risk of locoregional recurrences. Both chemotherapy and endocrine therapy seemed to be less effective after 10 or more years for patients with BMIs greater than 30 kg/m(2). CONCLUSION: Obesity is an independent prognostic factor for developing distant metastases and for death as a result of breast cancer; the effects of adjuvant therapy seem to be lost more rapidly in patients with breast cancer and obesity.

CEF is superior to CMF for tumours with TOP2A aberrations: a Subpopulation Treatment Effect Pattern Plot (STEPP) analysis on Danish Breast Cancer Cooperative Group Study 89D.

The aim of this study was to examine TOP2A gene copy number changes as a means to identify groups of breast cancer patients with superior benefit from treatment with anthracyclines. Tumour tissue was retrospectively collected and successfully analysed for TOP2A in 773 of 980 Danish patients randomly assigned to receive intravenous CMF (cyclophosphamide, methotrexate and fluorouracil) or CEF (cyclophosphamide, epirubicin and fluorouracil) in DBCG trial 89D. Subgroup analyses on this material published by Knoop et al. (J Clin Oncol 23:7483-7490, 2005) and updated by Nielsen et al. (Acta Oncol 47:725-734, 2008) demonstrated that superiority of CEF over CMF is limited to patients with TOP2A aberrations, defined as patients whose tumours have TOP2A ratio below 0.8 or above 2.0. The Subpopulation Treatment Effect Pattern Plot (STEPP) technique was applied to these data to explore the pattern of treatment effect relative to TOP2A and to compare that pattern to the ranges previously used to define 'aberrations'. The pattern of treatment effect illustrated by the STEPP analysis confirmed that the superiority of CEF over CMF is indeed limited to patients whose tumours have high or low TOP2A ratios. The hypothesis of no treatment effect-covariate interaction was rejected (P = 0.02). Furthermore, results indicated that the interval of TOP2A ratios hitherto denoted as 'normal' could be narrower than previously assumed. A more optimal separation of TOP2A subgroups could be obtained by altering cut-points currently used to define TOP2A amplified and TOP2A deleted tumours by narrowing the TOP2A normal interval, and consequently enlarging the population with TOP2A aberrated tumours.