Stereotatic radiosurgery of 468 brain metastases < or =2 cm: implications for SRS dose and whole brain radiation therapy.
OBJECTIVE
The national standard stereostatic radiosurgery (SRS) dose for brain metastases < or =2 cm is 24 Gy as established by the Radiation Therapy Oncology Group study 90-05, in which planned whole brain radiotherapy (WBRT) was not used. On the basis of our institutional experience, the goal of this study was to determine the optimal SRS dose and influence of WBRT on local tumor control among 468 < or =2-cm metastases.


METHODS
Between October 1992 and May 2001, 468 newly diagnosed or recurrent < or =2-cm brain metastases, among 160 patients, were treated with SRS (dose range, 7-30 Gy; median, 20). A total of 240 metastases received planned WBRT (range, 6.75-50.4 Gy; median, 40.5) vs. 228 metastases that did not. The variables tested by multivariate analysis for their potential effect on tumor control included histologic type, site of metastasis, primary diagnosis, tumor volume, SRS dose, newly diagnosed vs. recurrent metastasis, and planned WBRT vs. no planned WBRT.


RESULTS
Follow-up ranged from 1 to 82 months (median 7). On multivariate analysis, the addition of WBRT was the most significant predictor of local tumor control. Overall, patients who received WBRT had superior local tumor control rates (97% vs. 87% in those who did not receive WBRT; p = 0.0001). Patients receiving WBRT and SRS > or =20 Gy achieved local control rates of 99% compared with 91% control rates when treated with WBRT and SRS <20 Gy (p = 0.0029). Increasing the SRS dose to >20 Gy resulted in no improvement in local tumor control and a higher rate of Grade 3 and 4 neurotoxicity, approaching statistical significance (5.9% vs. 1.9%, p = 0.078).


CONCLUSIONS
First, optimal control of brain metastasis < or =2 cm was seen with 20-Gy SRS combined with planned WBRT. Second, SRS doses >20 Gy resulted in no obvious improvement in local control and appeared to be associated with a greater rate of complications.
Shehata
Michael K
MK
Department of Radiation Medicine, University of Kentucky, Lexington, KY, USA.
Young
Byron
B
Reid
Brady
B
Patchell
Roy A
RA
St  Clair
William
W
Sims
Jackie
J
Sanders
Michael
M
Meigooni
Ali
A
Mohiuddin
Mohammed
M
Regine
William F
WF
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000473:pathology / Q000556:secondary* / Q000601:surgery*; D016371:Cranial Irradiation / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000601:surgery*; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage