Solitary Brain Metastasis from Non-Small Cell Lung Cancer: Treatment with Linac-Based Stereotactic Radiosurgery

The best treatment option for isolated brain metastasis is not well established and there is no consensus on this argument. It is still being debated whether patients with isolated brain metastasis of non-small cell lung cancer (NSCLC) should undergo surgical resection or stereotactic radiosurgery, and which patients should receive adjuvant whole brain irradiation. The median survival in patients with single or multiple metastatic lesions who underwent stereotactic radiosurgery improved from 2-3 months to 9 months. In the case of single brain metastases from NSCLC, life expectancy is mainly influenced by general conditions of the patient and the definitive treatment of the primary lung tumor. From a technical point of view, the radiosurgery approach exploits the volume-dependency of normal tissue radiation tolerance. Radiosurgery irradiation focuses high conformal doses only to small tumors (usually less than 4. cm), with steep gradient dose, in a single fraction, with an ablative intent. With such a technique able to conform very high doses only to the focal target, the risk of side effects is usually reduced compared to conventional radiotherapy techniques. The most commonly available radiosurgery technology uses high-energy X-rays generated from a clinical linear accelerator, or "LINAC". Compared to surgery for isolated brain metastasis, radiosurgery avoids the interventional risks of hemorrhage, infection, and tumor seeding, requiring minimal or no hospitalization, reducing the costs of therapy. Thus, LINAC-based radiosurgery represents a non-invasive, well tolerated and potentially effective treatment option for isolated metastasis in lung cancer patients.