Treatment of brain metastases from lung cancer: chemotherapy

Abstract

Brain metastases are a frequent complication in patients suffering from Lung cancer, and a significant cause of morbidity and mortality. Brain metastases are found in about 10% of patients at the time of diagnosis, and approximately 40% of all patients with lung cancer develop brain metastases during the course of their disease. The prognosis of these patients is rather poor. The standard treatment for brain metastases, so far, has been whole-brain radiation therapy and surgery focussing on symptom palliation. The use of chemotherapy for the treatment of brain metastases has been limited because of a presumed lack of effectiveness due to the blood-brain barrier. However, the importance of the blood-brain barrier is probably overrated in the case of macroscopic metastases or relapsed disease as the blood-brain barrier has already been disrupted at this stage resulting from the newly developed blood vessels not provided with the physiological properties of the common blood-brain barrier. Chemotherapeutic agents initially lipid-insoluble or liquor-impermeable can also penetrate into the brain and, therefore, trigger action against tumour cells. A number of clinical trials have demonstrated that brain metastases resulting from both small-cell lung cancer and non-small-cell lung cancer are susceptible to systemic chemotherapy. In small-cell lung cancer, cerebral response rates up to 50% were observed even in the second-line situation and were comparable to the response rates observed in the primary tumour. In non-small-cell lung cancer, similar results were achieved. Therefore, it seems justified to further evaluate the significance of chemotherapy compared to whole-brain radiation therapy. Whether chemotherapy alone is superior to whole-brain radiation therapy, or whether the combination of both therapeutic modalities should be preferred for the management of brain metastases, has not yet been proven, and further randomised phase-III studies are clearly needed. Based on the current available data, and the promising response rates in patients with lung cancer, chemotherapy should be considered for the management of brain metastases as part of a multimodality (or "interdisciplinary") treatment concept.