The postoperative management of patients with limited intracranial metastatic disease remains controversial. The potential morbidity of whole brain radiotherapy (WBRT) particularly observed in long term survivors leaded to develop new strategy to defer WBRT. We analyzed our experience delivering gamma knife to the tumor bed (TB) after resection of brain metastases.

We performed a retrospective review of patients who underwent postoperative radiosurgery after total resection of brain metastases between January 2011 and September 2013. The median dose to the 50% isodose line was 20Gy. We analyzed the influence of the local control, the distant recurrence, a diameter superior to 20mm and an isodose superior to 20Gy on the overall median survival time (MST). These results were compared to patients who underwent surgery followed by whole brain radiotherapy (WBRT). Kaplan–Meier curves were analyzed with a Long Rank test and multivariate Cox model proportional hazards regression were performed.

Radiosurgery was delivered on the tumor bed for 22 patients. The MST was 13months compared to 11months for the patients who received WBRT without significant difference. Of the 22 patients, 2 (9%) of the 22 patients failed to the local control and 12 (55%) developed distance brain recurrence. Thirteen patients (59%) received a 50% isodose>20Gy and for 12 (55%) patients the resection cavity has a diameter>20mm. The MST for patients with distance recurrence was 12 months versus 20 months without distant recurrence (P=0.032). No significant difference was founded between the isodose and diameter groups. Multivariate regression confirmed that the distance control of the brain disease is a good prognostic factor (HR 0.075, 95% CI0.008-0.693, P=0.022).

Surgical resection associated to Gamma Knife radiosurgery to the tumor bed is an effective treatment for well-selected patients. The risk of distance recurrence should be evaluated before to prefer this postoperative strategy to WBRT.