BMC Cancer Research article Potential antitumor effects of nitrogen-containing bisphosphonate in hormone receptor negative breast cancer patients with bone metastases In Hae Park1, Jungsil Ro*1, Byung Ho Nam2, Youngmi Kwon1 and Keun Seok Lee1 BioMed Central Open Access Address: 1Center for breast cancer, National cancer center, Goyang-si, Korea and 2Center for clinical trial, National cancer center, Goyang-si, Korea Email: In Hae Park - parkih@ncc.re.kr; Jungsil Ro* - jungsro@ncc.re.kr; Byung Ho Nam - byunghonam@ncc.re.kr; Youngmi Kwon - ymk@ncc.re.kr; Keun Seok Lee - kslee@ncc.re.kr * Corresponding author Published: 20 May 2009 BMC Cancer 2009, 9:154 doi:10.1186/1471-2407-9-154 This article is available from: http://www.biomedcentral.com/1471-2407/9/154 Received: 3 February 2009 Accepted: 20 May 2009 © 2009 Park et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: This retrospective study evaluated, according to hormone receptor status, the antitumor effects of bisphosphonate especially on survival and disease progression in breast cancer patients with metastatic bone disease. Methods: Of 317 patients with initial bone metastasis and known breast cancer subtypes, 230 patients (72.6%) had hormone receptor (HR) positive tumors, and 87 patients (27.4%) had HR negative tumors. We assessed the primary outcome of overall survival (OS), after adjusting for other factors, comparing a group that received bisphosphonates (BPs) with a group that did not receive it. Results: 87.8% of HR positive and 69.0% of HR negative patients received BPs with a median number of 17.7 cycles. Although BPs treatment made no survival benefit in HR positive group, HR negative patients showed a significant prolonged survival when they received BPs treatment (hazard ratio = 0.56 [95% CI 0.34 to 0.91], P = 0.019). In multivariate analysis, disease free interval > 2 years (P = 0.036), a sum of metastatic sites < 3 (P = 0.034), and BP treatments (P = 0.007) were significant factors for survival in HR negative patients. Conclusion: Bisphosphonate treatment can result in a survival benefit in metastatic breast cancer patients with HR negative tumors. Background Bone metastases are common in patients with advanced breast cancer. The median survival time after the diagnosis of bone metastases is approximately two years, although it may increase with new treatment regimens [1]. As patients survive longer, the incidence of associated prob- lems with metastatic bone disease (MBD), such as patho- logic fracture or spinal cord compression, increases, and these complications may substantially reduce a patient's quality of life [1,2]. Over the past decade, bisphospho- nates (BPs) have become the standard therapy for breast cancer patients with bone metastasis. It is now clear that the bisphosphonates reduce both the symptoms and com- plications of bone involvement [3]. In addition, the anti- Page 1 of 9 (page number not for citation purposes)