Correlation of BMI with tumor stage in early breast cancer patients (pts): Pooled analysis of the German SUCCESS A, B, and C trials.

Abstract

1602 Background: Independent from known prognostic factors, e.g., tumor size and nodal status, obesity is a risk factor for poor disease free, distant disease free, and overall survival in breast cancer. The aim of this analysis was to examine the correlation of the body mass index (BMI) with tumor characteristics in early breast cancer. Methods: We analyzed the data of 7,997 pts with early, node positive or high risk node negative primary breast cancer treated with adjuvant taxan-based chemotherapy within the German multicenter phase III SUCCESS A, B, or C trials. The pts’ tumor stage at primary diagnosis was classified according to the UICC tumor-node-metastasis (TNM) classification. Additionally, the tumor’s hormone-receptor status and HER2/neu status were determined. Before enrollment into the study each patient was grouped according to the WHO global database on BMI. Contingency table methods were used to analyze the correlation of BMI and tumor characteristics. Results: Among the 7,997 pts 100 (1.3%) pts were underweight, 3,556 (44.5%) pts were normal weight, 2,569 (32.1%) pts were overweight and 1,772 (22.2%) were obese. Of all pts 4,508 pts (56.4%) suffered from a pT2-4 tumor, 4830 (60.4%) showed lymph node involvement (pN1-3) and 7509 (93.9%) had G2-3 tumors. 5839 pts (73.0%) showed positivity for ER or PR and 935 (11.7%) for HER2/neu. Overweight and obese pts had significantly larger tumors compared to pts with normal BMI (p<0.0001; p<0.0001). Furthermore, overweight and obesity were associated with a significantly higher rate of lymph node involvement (p=0.0001; p=0.0003) respectively. In contrast neither grading, tumor histology, ER/PR-status nor HER2/neu-overexpression were correlated with BMI. Conclusions: These data are the first to show in a large number of pts that both obese and overweight women suffering from primary breast cancer have significantly larger tumors and more often positive axillary lymph nodes. As there are no differences in tumor biology, the advanced tumor stage might be due to more difficult and delayed detection of breast cancer and lymph node lesions in these women.