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B. Woo, S. Maswadi, N. Kumar, M.L. Meltz, R.D. Glickman; In vitro Melanoma Response to Combined Radiation and Laser Treatment . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2233.
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© ARVO (1962-2015); The Authors (2016-present)
Brachytherapy radiation treatment for ocular choroidal melanoma is effective, but can cause significant long–term side effects including maculopathy and optic nerve atrophy. Laser thermotherapy of tumors alone may be insufficient to treat tumors, but combined transpupillary thermotherapy and brachytherapy showed promising results in pilot studies. However, the dose response of the combination therapy has not been established. This study attempts to determine the dose response curve of melanoma cell kill using the combination therapy.
Human melanoma cells (CRL–11147) were obtained from ATCC. In 24–well culture plates, 500 cells were seeded into each well. One plate was exposed to diode laser only (806nm, Power Technology) with the irradiance set at 1W/cm2 for 5 minutes per well. One plate received a combination of laser treatment, as detailed above, plus 405 cGy gamma radiation (3.4 min in a Gammacell 40 Ce–137 irradiator with a dose rate of 119.1 cGy/min). One plate received 405 cGy gamma radiation only. An untreated plate served as control. Cell growth was taken as the total protein per well measured by BCA assay (Pierce).
In the absence of any radiation or laser exposure, the cells showed steady growth over 5 days. The cells that received the combined laser and gamma radiation had the most growth retardation and did not show significant growth until day 5 (p=0.004, Bonferroni multiple comparison). The cells that received laser or gamma radiation only, showed modest growth retardation with significant growth resuming by day 3 (p=0.002).
While the present experiment did not define an optimal dose combination for the two treatment modalities, it did indicate that combination therapy produces synergistic effects. This might reduce the side effects associated with each treatment type by enabling the use of lower dosages. Future experiments will define the optimal dose combination of the two treatment modalities.
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