379P - Risk factors for developing skeletal-related events associated with metastatic breast cancer patients receiving bone-modifying agents

Date 27 September 2014
Event ESMO 2014
Session Poster Display session
Topics Supportive measures
Breast Cancer
Presenter Ryota Tanaka
Citation Annals of Oncology (2014) 25 (suppl_4): iv116-iv136. 10.1093/annonc/mdu329
Authors R. Tanaka1, K. Yonemori1, A. Hirakawa2, J. Hashimoto3, M. Kodaira3, H. Yamamoto1, M. Yunokawa3, C. Shimizu3, M. Fujimoto4, Y. Fujiwara3, K. Tamura3
  • 1Department Of Breast And Medical Oncology, National Cancer Center Hospital, 104-0045 - Tokyo/JP
  • 2Center For Advanced Medicine And Clinical Research, Nagoya University Hospital, Nagoya/JP
  • 3Department Of Breast Oncology And Medical Oncology, National Cancer Center Hospital, 104-0045 - Tokyo/JP
  • 4Department Of Dermatology, University of Tsukuba, Tsukuba/JP

Abstract

Aim

Bone-modifying agents (BMAs) reduce the incidence of skeletal-related events (SREs) and are recommended for breast cancer patients with bone metastasis. However, the risk factors for developing SREs, during BMA treatment, are not adequately studied. This study evaluated the time to first SRE and the time between first and multple SREs in order to identify the factors predicting SREs.

Methods

The medical records of 534 women with breast cancer who developed bone metastasis, between 1999 and 2011, were reviewed. SREs were defined as a pathologic fracture, spinal cord compression, or the necessity of bone irradiation or surgery. The factors investigated included the type of primary cancer, performance status, menopause status, presence of extraskeletal metastasis, prior history of bone fractures and palliative radiation therapy, serum levels of lactate dehydrogenase and calcium corrected for albumin level at the time of the initial BMA dose, BMA type, and time between the first diagnosis of bone metastasis and the initiation of BMAs (0-6 months vs. above 6 months). These factors were analyzed using Cox proportional hazard analyses and Andersen-Gill approach.

Results

Multivariate analyses indicated that significant baseline risk factors for the time to the first SRE included luminal B type disease (HR = 1.8, P = 0.006), presence of extraskeletal metastasis (HR = 1.7, P = 0.027), prior history of palliative radiation therapy (HR =1.7, P = 0.001), elevation of serum levels of calcium above normal (HR = 1.3, P = 0.002) on administyation of the initial BMA dose, or initiation of BMA treatment above 6 months (HR = 1.4, P = 0.044) after initial detection of bone metastasis. The significance of these factors was also observed in the analyses of multiple SREs.

Conclusions

To reduce the risk of SREs, BMAs should be initiated within 6 months of the diagnosis of bone metastasis, and before commencing palliative radiation therapy in breast cancer patients. For patients with luminal B breast cancer and existing extraskeletal metastasis, BMAs should be continued whenever possible.

Disclosure

All authors have declared no conflicts of interest.