Induced fluorescence of medullary carcinoma of the thyroid: A technology with potential to improve visualization of malignant tissue at the time of surgical resection
15503 Background: Surgery for medullary carcinoma of the thyroid can at times be technically challenging to the surgeon. Inducing the cancer cells to be fluorescent would have the potential to improve the surgeon’s ability to quickly and accurately identify and excise all of the malignant tissue. We have previously demonstrated the feasibility of induced tumor fluorescence with fluorophor-tagged anti-tumor antigen antibodies using human colon and breast cancer cell lines. We present here our results using a human medullary carcinoma of the thyroid cell line in the nude mouse model. Methods: A human medullary carcinoma of the thyroid cell line that was demonstrated to express CA 15–3 was used. Thyroid carcinoma cells were subcutaneously implanted in 4 nude mice (3 study mice and 1 control mice). Three weeks after injection, tumor nodules were easily detectable. Using the tail vein method, 3 study mice were injected with fluorophore-tagged anti-CA 15–3 and 1 control mouse with fluorophore-tagged IgG. Mice were examined using a small animal imaging system with a 470 nm light source and appropriate filters. They were also examined using a simple blue LED flashlight fitted with a fixed 470 nm band pass filter for illumination and were observed through filtered goggles. Results: Fluorescence of tumor nodules in the study mice could be seen through the skin. On dissection and exposure of the tumor nodules, this fluorescence was intense and clearly distinguishable from the surrounding normal tissue using either the imaging system or the blue LED. The control mouse injected with fluorophore-tagged IgG and examined in a similar manner revealed no tumor fluorescence. Conclusions: When tumor antigens are known, fluorophore-tagged antibody induced fluorescence is simple, easy to perform, requires no technically complex equipment or operator expertise and could be adapted to thyroid cancer surgery in the academic or community hospital setting. This technology would be indicated in those patients undergoing initial resection of medullary carcinoma of the thyroid as well as in those patients undergoing resection of recurrent disease where accurate identification of tumor tissue may be more difficult and time consuming. No significant financial relationships to disclose.