Hypofractionated stereotactic radiotherapy for brain metastases

Purpose. - A survey of the literature has been performed to find arguments in order to help the choice between radiosurgery and hypofractionnated stereotactic radiotherapy in the treatment of brain metastases. Patients and methods. - A comparison of two groups of brain metastases treated with hypofractionnated stereotactic radiotherapy or radiosurgery, with or without WBRT was performed. Hypofractionnated stereotactic radiotherapy: there were eight series including 448 patients published from 2000 to 2009; treated with 5-6 MV X-Rays, non invasive head immobilization, a margin 2 to 10 mm; 24 to 40 Gy in three to five fractions; a 5 to 8 days duration in six series and 15-16 days in two other series. WBRT (30%); radiosurgery: there were 12 series (1994 to 2005) including 2157 patients; an invasive head immobilization, no margin; doses from 10 to 25 Gy; six series over 12 had Gamma Knife radiosurgery and six had Linacs X-Rays. WBRT (30 Gy/10 F/12 days) associated to radiosurgery in several series. The following parameters were compared: median GTV, median survival, 1-year survival rate, local control rate, necrosis and WBRT rates. Results. - Hypofractionnated stereotactic radiotherapy series: the parameters were respectively: 0,52-4,47 cm(3) (median 2,8 cm(3)); 5-16 months (median 8,7 months); 68,2-93% (median 82,5%); necrosis rate 3,1%; associated WBRT 30%. Radiosurgery series: the parameters were respectively: 1,3 to 5,5 cm(3) (median 2 cm(3)); 5,5 to 22 months (median 11 months); 71 to 95% (median 85%); 0,5 to 6% (median 2,4%); associated WBRT 58%. Results seem similar in the two groups: Hypofractionnated stereotactic radiotherapy with non invasive immobilization could theoretically treat all brain metastases sizes except lesions < 10 mm (500 mm(3)). In large volumes, > 4200 mm(3) GTV, the toxicity of hypofractionnated stereotactic radiotherapy was not reported, thus it was difficult to compare its results with the published reports of radiosurgery toxicity. WBRT was a confusing parameter. Obviously, this initial survey has important limitations, specifically its methodology. Conclusion. - Radiosurgery and hypofractionnated stereotactic radiotherapy could be used to treat brain metastases with GTV > 500 mm(3) and <= 4200 mm(3) (circle divide 20 mm); for GTV < 500 mm(3) (circle divide 10 mm) an invasive procedure with radiosurgery is necessary. For GTV > 4200 mm(3) (circle divide 20 mm), hypofractionnated stereotactic radiotherapy could be proposed, provided further studies, using 4 to 6 Gy fractions, a duration less or equal to 10-12 days and a margin of 2 mm will be performed. (c) 2009 Societe francaise de radiotherapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.