Getting a better view of eye cancer

Marie Freebody, mariefreebody@physics.org

Retinoblastoma is the most common and aggressive form of eye cancer found in children under the age of 5. As with most cancers, early detection and accurate monitoring are critical for preservation of vision, retention of the eye and even survival. Today’s oncologists usually opt for MRI or CT to determine the progression of eye cancer; however, a higher-resolution technique using bioluminescence imaging (BLI) could enable doctors to better detect tumors.

In both of these images, bioluminescence imaging is used to show eye cancer metastasis foci in vivo. Courtesy of Shanghai Jiao Tong University Affiliated First People’s Hospital.

Devised by researchers at Shanghai Jiao Tong University Affiliated First People’s Hospital, the technique is not only more sensitive but also easier to use compared with MRI or CT, and it provides a more accurate correlation between cell numbers detected and tumor growth.

“Although the retina can be observed using optical instruments, it is still difficult to monitor tumor growth, especially at the early stage,” said professor Qian Huang, who led the study. “Our technique allows sensitive, noninvasive and quantitative localization and monitoring of intraocular and metastatic tumor growth in vivo.”

As detailed in the paper, which was published in the December 2009 issue of the journal Investigative Ophthalmology and Visual Science, BLI involves creating human eye tumors and attaching particular genes (known as fusion reporter genes) to label the cancerous cells.

Attaching fusion reporter genes to cell cultures is a common technique used in molecular biology to track cell populations. Huang and colleagues first engineered human eye cancer, or retinoblastoma, cells with a fusion reporter gene that allows for bioluminescence and fluorescence imaging. The marked tumor cells were then injected into the eye compartments of mice and monitored using a NightOwl LB 981 molecular imaging system from Berthold Technologies GmbH & Co. KG of Bad Wildblad, Germany. Huang’s team found that the BLI signal intensity correlated with the number of tumor cells injected as well as with the weight of the tumor-bearing eyes.

“This is the first report of using BLI to visualize retinoblastoma tumor growth and metastasis in vivo,” Huang said. “Our technique allows tiny metastatic lesions to be detected – lesions of a size that are impossible to detect with other imaging techniques such as CT or MRI.”

The study shows that BLI can be used successfully to track the growth of created tumors, but, according to Huang, the technique can be applied to detect any type of tumor, as long as the tumor cells are marked with the light-responsive reporter gene.

Although the team has no current plans to commercialize its technique, Huang hopes that the novel approach could be used to understand the biology and mechanism of tumor growth and to evaluate new antitumor therapies.