Early decreased tumor volume following fractionated Gamma Knife Radiosurgery for metastatic melanoma and the role of "adaptive radiosurgery": case report.
OBJECTIVE
We report a case in which fractionated gamma knife radiosurgery was used to treat a metastatic melanoma lesion. The tumor demonstrated a rapid response to radiosurgery with an observable reduction in tumor volume between the second and third treatments, requiring a favorable modification in the third fractionated treatment.


METHODS
A 61-year-old woman presented with a frontal floor metastatic melanoma lesion that was located adjacent to the optic apparatus.


METHODS
Gamma knife radiosurgery was administered in three fractionated treatments of 6.5 Gy to the 50% isodose line in each case. Repeat imaging for the purpose of planning demonstrated that tumor volume at the time of the third treatment, 9 days following the first treatment, had decreased by 31%, resulting in a 21% decrease in the dose administered to the optic chiasm.


CONCLUSIONS
A case of metastatic melanoma treated with fractionated GKRS is presented, in which a significant reduction in tumor volume was noted 9 days following the initial treatment. This case provides insight into the rate with which malignant neoplasms may respond to intermediate-dose hypofractionated GKRS, and lends support to the concept of "adaptive radiosurgery" as a means of optimizing radiation to an evolving target while minimizing collateral radiation to surrounding structures.
Zada
Gabriel
G
Department of Neurosurgery, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, USA. gzada@usc.edu
Yu
Cheng
C
Pagnini
Paul G
PG
Khalessi
Alexander A
AA
Zelman
Vladimir
V
Apuzzo
Michael L J
ML
D001932:Brain Neoplasms / Q000473:pathology* / Q000556:secondary / Q000601:surgery*; D005123:Eye / Q000473:pathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008545:Melanoma / Q000473:pathology* / Q000556:secondary / Q000601:surgery*; D008875:Middle Aged; D009897:Optic Chiasm / Q000473:pathology / Q000601:surgery; D016634:Radiosurgery