Association of the development of bone metastases with the development of brain metastases in patients with non-small cell lung cancer.

Abstract

e13030 Background: In patients (pts) with non-small cell lung cancer (NSCLC), it is unknown whether pts with bone metastases are predisposed to the development of brain metastases. The impact of bevacizumab (Bev) on the development of bone and brain metastases is not fully characterized. Methods: Retrospective review of pts with stage IV NSCLC without brain metastasis at diagnosis was undertaken. The primary endpoint was to determine whether the development of bone metastases is predictive of the development of brain metastases. Secondary endpoints involved the proportion of pts who developed brain and/or bone metastases while being treated with Bev. Data were analyzed using competing risks methods. Results: A total of 175 pts (52% males, median (range) age: 60 y (35-80)) were studied. Of whom 79% received Bev and 21% did not receive Bev as part of their treatment. Overall 34% of pts had bone metastases at the start of therapy. Pts with pre-existing bone metastases tended to develop new bone disease more frequently than pts who did not initially have bone metastases (39% vs. 19%, p =. 01). The incidence of the development of brain metastases among pts who had pre-existing bone metastases was 17% vs.16 % in pts without pre-existing bone metastases. However, the incidence of brain metastases among pts with pre-existing bone disease who developed new bone metastases was 33% vs. 6% in pts who did not develop new bone disease but had pre-existing bone metastases. Adjusting for initial bone disease, development of new bone metastases was associated with a shorter brain metastases-free interval HR 5.06 (2.03-12.65; p = 0.005). In a subgroup analysis based on Bev exposure, the likelihood of developing brain and bone metastases within 2 years of starting Bev was estimated to be 25% and 27%, respectively, while the likelihood of developing brain and bone metastases without Bev treatment was 33% and 43 %, respectively. Conclusions: In pts with NSCLC, the development of new bone metastases may be indicative of the subsequent development of brain metastases. Additionally, Bev therapy may have an effect on the development of both bone and brain metastases. A prospective investigation may be warranted.