| Benefits of Multisession Cyberknife Stereotactic Radiotherapy for Perioptic Lesions ; Visual Outcome and Tumor Control |
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In Jae Choi, Sukh Que Park, Hyung Ki Park, Sung Jin Cho, Jae Chil Chang |
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Department of Neurosurgery, Soonchunhyang University Seoul Hospital, Seoul, Korea |
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| Abstract |
Background
Radiosurgery may be contraindicated for lesions adjacent to the optic pathways because of the substantial risk
of visual complication. Multisession Cyberknife (CK) Stereotactic Radiotherapy (SRT) has been tried as a compared with CK
Stereotactic Radiosurgery (SRS). The purpose of this study is to evaluate the outcomes of Cyberknife Stereotactic Radiotherapy
in consecutive 22 patients with perioptic lesions.
Methods
Between 2008 and 2011, 22 cases, patients with meningioma (n=16), pituitary adenoma (n=2), craniopharyngioma
(n=2), hemangioblastoma (n=1), neuroblastoma (n=1) situated within 2mm of a short segment of the optic apparatus underwent
CK SRT or SRS in our hospital. Four patients underwent CK SRS and 18 patients underwent CK SRT. CK SRT was delivered in
two to five sessions to an average tumor volume of 11,644mm3
and a cumulative average marginal dose of 2,314.7cGy. CK
SRS was delivered in one session to an average tumor volume of 1,972mm3
and a cumulative average marginal dose of
2,075cGy. We focused patient visual symptom (diplopia, ptosis, exophthalmia, limited ROM, blindness, visual disturbance, etc.)
and tumor size. All patients were evaluated by visual examination and image study before radiosurgery. The response was assessed by visual examination and image study after radiosurgery.
Results
Tumor control was achieved in 19 patients (three CK SRS patient, sixteen CK SRT patient). Eighty-nine percent of SRT
group was controlled, on the other hand, seventy-five percent of SRS group was controlled. In CK SRT group, tumor volume
was decreased from 11,644±14,224mm3
to 10,098±11,662mm3
and In CK SRS group, tumor volume was decreased from
1,972±1,384mm3
to 1,933±1,392 mm3
. In CK SRT group, rate of volume change was 7±8.13% of between initial and 6months
follow up, 1.63±3.15% of between 6months and 12months follow up, 1.16±1.71% of between 12months and 24months follow up and In CK SRS group, rate of volume change was 1±1.73% of between initial and 6months follow up, 1.5±1.66% of between 6months and 12months follow up, 1±1.22% of between 12months and 24months follow up. CK SRT had better response than CK SRS in 2.931 times. Visual function improved in four patients, remained unchanged in twelve and deteriorated
in five patient. Seventy-five percent of SRS group were stable in vision and seventy-six percent of SRT were stable similarly. The
difference was not statistically significant.
Conclusion
CK SRT resulted a little better tumor control and preservation of visual function in perioptic lesions than CK SRS.
We can’t emphasize these results, because of the small number of patients, short term follow-up periods and only small lesion
applied in CK SRS. So, longer follow-up periods with more patients are needed to completely validate these conclusions. |
| Key Words:
Multisession, Cyberknife, Stereotactic radiotherapy, Stereotactic radiosurgery, Perioptic. |
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