Date Published: March 1, 2017
Publisher: Public Library of Science
Author(s): Il Yong Chung, Jong Won Lee, Ji Sung Lee, Yu Rang Park, Yul Ha Min, Yura Lee, Tae In Yoon, Guiyun Sohn, Sae Byul Lee, Jisun Kim, Hee Jeong Kim, Beom Seok Ko, Byung Ho Son, Sei Hyun Ahn, Scott M. Langevin.
The aim of this study was to determine the relationship between the body mass index (BMI) at a breast cancer diagnosis and various factors including the hormone-receptor, menopause, and lymph-node status, and identify if there is a specific patient subgroup for which the BMI has an effect on the breast cancer prognosis. We retrospectively analyzed the data of 8,742 patients with non-metastatic invasive breast cancer from the research database of Asan Medical Center. The overall survival (OS) and breast-cancer-specific survival (BCSS) outcomes were compared among BMI groups using the Kaplan-Meier method and Cox proportional-hazards regression models with an interaction term. There was a significant interaction between BMI and hormone-receptor status for the OS (P = 0.029), and BCSS (P = 0.013) in lymph-node-positive breast cancers. Obesity in hormone-receptor-positive breast cancer showed a poorer OS (adjusted hazard ratio [HR] = 1.51, 95% confidence interval [CI] = 0.92 to 2.48) and significantly poorer BCSS (HR = 1.80, 95% CI = 1.08 to 2.99). In contrast, a high BMI in hormone-receptor-negative breast cancer revealed a better OS (HR = 0.44, 95% CI = 0.16 to 1.19) and BCSS (HR = 0.53, 95% CI = 0.19 to 1.44). Being underweight (BMI < 18.50 kg/m2) with hormone-receptor-negative breast cancer was associated with a significantly worse OS (HR = 1.98, 95% CI = 1.00–3.95) and BCSS (HR = 2.24, 95% CI = 1.12–4.47). There was no significant interaction found between the BMI and hormone-receptor status in the lymph-node-negative setting, and BMI did not interact with the menopause status in any subgroup. In conclusion, BMI interacts with the hormone-receptor status in a lymph-node-positive setting, thereby playing a role in the prognosis of breast cancer.
There has been some controversy about whether the body mass index (BMI) at the diagnosis of breast cancer is associated with the patient outcome. Several clinical trials have demonstrated that obesity at diagnosis is associated with breast-cancer-specific survival (BCSS) and overall survival (OS) [1–3], which was additionally supported by recent meta-analyses . However, other studies have found no association between BMI and the prognosis of breast cancer [5–7].
The findings of our current study indicate that an interaction between the BMI and the hormone-receptor status at the diagnosis of breast cancer plays a role as a prognostic factor for this disease only in the lymph-node-positive setting. Obesity was found to be associated with significantly poorer breast-cancer-specific survival in hormone-receptor-positive breast cancer, but a better survival outcome in hormone-receptor-negative breast cancer cases, although this was not statistically significant. However, UW in hormone-receptor-negative breast cancer demonstrated a trend toward a poorer OS and significantly poorer BCSS. There was no significant interaction found between BMI and hormone receptor in lymph-node-negative breast cancer patients. Additionally, there was no significant interaction found between BMI and menopause status in any of the study populations.