Osteoblastic reaction in non-small cell lung carcinoma and its association to epidermal growth factor receptor tyrosine kinase inhibitors response and prolonged survival.

Introduction: The aim of this study was to describe the characteristics and epidermal growth factor receptor (EGFR) mutational status of patients with non-small cell lung cancer (NSCLC) with osteoblastic reactions diagnosed before or during treatment with EGFR tyrosine kinase inhibitors (TKIs).
Methods: Retrospective study including patients with 36 NSCLC with at least one site of osteoblastic reaction at the time of diagnosis or during treatment with EGFR-TKI.
Results: The rate of patients with mutated EGFR tumors with osteoblastic reactions before or after EGFR-TKI treatment was similar. Median progression-free survival (PFS) for the entire group was more than 9 months and median survival was more than 12 months. There was no statistically significant difference in survival between patients with osteoblastic reactions before initiation of TKI and those diagnosed during TKI treatment. Patients with extraosseous metastases when treated with TKI had the lowest survival (P < 0.0001).
Conclusions: In patients with NSCLC treated with TKI, initial or development of an osteoblastic reaction seems to be related to a more favorable outcome. In patients with osteoblastic reactions, tumors present with clinical and biologic characteristics of better survival and response to TKI. The occurrence of osteoblastic reactions during treatment with TKI, while primary tumor and metastases are stable or in response, should not be considered as disease progression.