Combined treatment for non-small cell lung cancer and breast cancer patients with brain metastases with whole brain radiotherapy and temozolomide: a systematic review and meta-analysis

Brain metastasis is the leading cause of death among advanced non-small cell lung cancer (NSCLC) and breast cancer patients. The standard treatment for brain metastases is radiotherapy. The combination of radiotherapy and chemotherapy has been tested. However, the management of brain metastases has yet to be successful. Here, we aimed to determine the efficacy and safety of whole brain radiotherapy (WBRT) alone or in combination with temozolomide (TMZ) in NSCLC and breast cancer patients with brain metastases. A systematic review of PubMed, CNKI (China National Knowledge Infrastructure) and WANFANG (WANGFANG data) involving 870 patients were conducted. Fourteen randomized controlled trials (RCTs) were independently identified by two reviewers. The primary outcome measures were objective response rate (ORR), overall survival (OS), progression-free survival (PFS) and toxicity. The ORR was better with combination therapy of WBRT and TMZ than with WBRT alone (RR = 1.34, p < 0.00001) and subgroup analysis showed a significantly superior ORR in NSCLC patients (RR = 1.38, p < 0.00001), but not in breast cancer patients (RR = 1.03, p = 0.86). OS and PFS did not significantly differ between combination therapy and WBRT alone. A higher rate of toxicity was observed in combination therapy than in WBRT alone (RR = 1.83, p = 0.0006). No advantages of concurrent WBRT and TMZ were observed in breast cancer patients with brain metastases. Combination therapy was associated with improved ORR in NSCLC patients, especially in Chinese patients. As a “surrogate endpoint” for OS, ORR may allow a conclusion to be made about the management of NSCLC with brain metastases with the combination of WBRT and TMZ. However, it needs to be validated to show that improved ORR predicts the treatment effects on the clinical benefit. The ORR may be valid for a particular indication such as status of MGMT promoter methylation.