Increased risk of SSEs in bone-only metastatic breast cancer patients treated with zoledronic acid

Masashi Yanae; Shinichiro Fujimoto; Kaori Tane; Maki Tanioka; Kimiko Fujiwara; Masanobu Tsubaki; Yuzuru Yamazoe; Yoshiyuki Morishima; Yasutaka Chiba; Shintaro Takao; Yoshifumi Komoike; Junji Tsurutani; Kazuhiko Nakagawa; Shozo Nishida

doi:10.1016/j.jbo.2017.08.004

Increased risk of SSEs in bone-only metastatic breast cancer patients treated with zoledronic acid

J Bone Oncol. 2017 Aug 31:8:18-22. doi: 10.1016/j.jbo.2017.08.004. eCollection 2017 Sep.

Authors

Affiliations

¹ Department of Pharmacy, Kindai University Hospital, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, Japan.
² Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, 3-4-1 Kowakae, Higashi-Osaka, Osaka, Japan.
³ Departments of Breast Surgery and Hyogo Cancer Center, 13-70 Kitaoji-cho, Akashi, Hyogo, Japan.
⁴ Medical Oncology, Hyogo Cancer Center, 13-70 Kitaoji-cho, Akashi, Hyogo, Japan.
⁵ Clinical Research Center, Kindai University Hospital, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, Japan.
⁶ Departments of Surgery and Kindai University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, Japan.
⁷ Medical Oncology, Kindai University Faculty of Medicine, 377-2 Ohno-higashi, Osaka-Sayama, Osaka, Japan.

Abstract

Background: Bone represents one of the most common sites to which breast cancer cells metastasize. Patients experience skeletal related adverse events (pathological fractures, spinal cord compressions, and irradiation for deteriorated pain on bone) even during treatment with zoledronic acid (ZA). Therefore, we conducted a retrospective cohort study to investigate the predictive factors for symptomatic skeletal events (SSEs) in bone-metastasized breast cancer (b-MBC) patients.

Methods: We retrospectively collected data on b-MBC patients treated with ZA. Patient characteristics, including age, subtype, the presence of non-bone lesions, the presence of multiple bone metastases at the commencement of ZA therapy, duration of ZA therapy, the time interval between breast cancer diagnosis and the initiation of ZA therapy, and type of systemic therapy, presence of previous SSE were analyzed using multivariable logistic regression analysis.

Results: The medical records of 183 patients were reviewed and 176 eligible patients were analyzed. The median age was 59 (range, 30-87) years. Eighty-seven patients were aged ≥60 years and 89 patients were aged < 60 years. The proportions of patients with estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2-positive disease were 81.8%, 63.1%, and 17.6%, respectively. Fifty-three patients had bone-only MBC at the commencement of ZA therapy. SSEs were observed in 42 patients. In the multivariable logistic regression analysis, bone-only MBC but not a breast cancer subtype was an independent risk factor for an SSE during ZA therapy (odds ratio: 3.878, 95% confidence interval: 1.647-9.481; p = 0.002).

Conclusions: Bone-only MBC patients are more likely to experience an SSE even after treatment with ZA.

Keywords: BP, bisphosphonate; Bone metastasis; Breast cancer; CI, confidence interval; ER, estrogen receptor; HER2, human epidermal growth factor receptor 2; HR, hormone receptor; MBC, metastatic breast cancer; OR, odds ratio; PgR, progesterone receptor; Retrospective cohort study; SRE, skeletal related adverse event; SSE, symptomatic skeletal event; Symptomatic skeletal events; TN, triple-negative; ZA, zoledronic acid; Zoledronic acid; b-MBC, bone-metastasized breast cancer.