Lung cavitation in lung metastases of gastric and non-small-cell lung cancer patients treated with apatinib

In one of the latest issues of Translational Lung Cancer Research (TLCR), Jiang et al. have reported on the frequent cavitation of lung metastases in metastatic lung and gastric cancer patients following treatment with apatinib. It has been recognized that anti-angiogenic compounds surface among the anti-cancer therapies, inducing lung cavitation. Although lung cavitation was not found to influence PFS and OS in previous studies (1), the study of Man Jiang, directed by Xiaochun Zhang, has shown that apatinib induces cavitation of lung metastases in a significant number of patients treated with apatinib. Detection of cavitation of lung metastases was associated with longer PFS and OS. What is lung cavitation? Cavitary lung diseases have, for a long time, been an object of study and have broad differential diagnoses. The study of Jiang et al. opens the gates for further clarification of this subject. A cavity is defined as a gas-filled space, seen as a lucency or low attenuation area, between a nodule, mass or area of parenchymal consolidation. It also has a clearly defined wall, 4 mm thick (2). Multiple peripheral nodules in variant stages of cavitations could indicate septic emboli, pulmonary Langerhans cell histiocytosis, possible infarction or tumors with hemorrhage. True cavities should be differentiated from cystic disease, emphysema, infected bullae and cystic bronchiectasis. Cavities are relatively frequent in lung cancer, with an incidence of up to 20% in chest CT scans. Pulmonary metastases can also cavitate. In the current study, the lung cavitation was clearly associated with apatinib treatment, since it occurred in a short period of time, less than 12 weeks, according to prior imaging. What is apatinib? Apatinib is a multi-receptor tyrosine kinase (RTK) inhibitor that was originally studied in patients with non-small cell lung cancer and gastric cancer in China (3). Apatinib has been approved to treat advanced or metastatic chemo-resistant gastric cancer in China. Apatinib is an orally administered RTK inhibitor that targets the vascular endothelial growth factor receptor-2 (VEGFR-2), RET, platelet-derived growth factor-β (PDGFR-β), c-Src and stem cell factor receptor (c-Kit) (4). Apatinib has been used in combination with pemetrexed and carboplatin in non-squamous non-small-cell lung cancer (5) and in combination with docetaxel in lung adenocarcinoma (6). Although apatinib has significant side effects, like hypertension, hand foot syndrome, fatigue and others, at lower doses of 250 mg per day it is well tolerated (6)