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Enrique et al. J Cancer Metastasis Treat 2019;5:54 I http://dx.doi.org/10.20517/2394-4722.2019.20 Page 11 of 16

Figure 6. Treatment-planning dose for SRS of a single lesion, with the dose distribution for one target prescribing 20 Gy 95% with the
following specification: isodose lines: red 20 Gy, yellow 18 Gy, blue 16 Gy, brown 12 Gy, pink 6 Gy. Software: Eclipse External Beam
Planning system version 15.5 HD MLC

Figure 7. Multiple-target planning showing the dose distribution for multiple targets, prescribing 20 Gy 95% to each of them with the
following specification: isodose lines: red 20 Gy, green 18 Gy, light blue 16 Gy, yellow 12 Gy, dark blue 6 Gy. Software: Eclipse External
Beam Planning system version 15.5 HD MLC

metastases did not impact local control, and the rate of distant metastasis failure was lower in patients with
a single metastasis, although this advantage seemed to be lost for those with two or more metastases .
[62]
Because 50% of patients with brain metastases will present with new lesions, it is necessary to continue
surveillance using serial MRI when only SRS is used, with the intention of identifying the progression of
the disease and enabling early management to limit neurological deficits. Success in the control of new
distant metastases varies from 22% to 90%, with different results reported by different studies. Many such
studies have reported a correlation between the initial number of metastases and the progression of disease
(according to Chang et al. , the presence of 15 or more metastases is a risk factor). In addition to age, KPS,
[61]
histology, and RPA, the total irradiated volume is also likely to impact overall survival, however, neither
the number of metastases nor the total volume of treatment is yet considered a criterion for the selection of
patients for treatment with SRS .
[51]
Brown’s and Chang’s trial [60,61] indicated that treatment with WBRT affects cognitive function in a significant
way in all analyzed aspects, and opinions on the management of brain metastases converge on the use of
SRS, even for multiple brain metastases, to avoid cognitive deficit .
[55]