Object. The objective of this retrospective study was to analyze the results of stereotactic radiosurgery performed using a gamma knife in the treatment of 44 consecutive patients with brain metastases from lung carcinoma.
Methods. Forty-four patients with lung carcinoma were treated for metastatic brain tumors by performing radiosurgery with a Leksell Gamma Knife. Twenty-one patients (47.7%) were women and 23 were men. The mean age of the patients was 56 years (range 35–77 years). Twenty-two patients (50%) had solitary tumors and the rest had multiple tumors (two—six lesions). Eighteen patients (40.9%) presented with a recurrent and/or progressive brain disease that previously had been treated with other modalities (surgery, external-beam radiotherapy, or both). Fifteen patients had controlled lung disease and 19 patients had systemic metastases (in lymph nodes, liver, and/or bones) at the time of radiosurgery.
The median follow-up period was 18.25 months. All patients were followed up for three different end points: 1) death caused by the disease; 2) clinical and/or radiological evidence of progression of the tumor that had been treated with radiosurgery; and 3) appearance of new lesions. At the last follow-up review, 17 patients (38.6%) were alive and 27 (61.4%) had died. Ten patients (22.7%) died as a result of brain disease (failure of local control or new metastases). Controlled primary disease at the time of detection of metastases and the ability to achieve local tumor control after radiosurgery significantly improved the patient survival (p < 0.01). Control of the treated tumor(s) was achieved in 32 of 44 patients (72 tumors) and 10 patients experienced treatment failure. In addition to the 44 patients comprising the study population, two other patients were treated, but died of lung disease too early in the follow-up period to have been assessed. As of the last follow-up review, no new brain metastasis had occurred in 36 patients (81.8% [includes surviving and nonsurviving patients]). The median duration of overall survival was 7 months, the median period of controlled brain disease was 21 months, and the median period of freedom from new brain metastases was 17 months (95% confidence interval 13–19 months).
Conclusions. Gamma knife surgery has significantly reduced the incidence of mortality from brain disease by effectively accomplishing local tumor control in patients with metastatic lung cancer. Local control and freedom from new brain metastases is not influenced by prior external-beam radiotherapy.