For many types of cancer, surgical resection is the best or only chance for cure. Incomplete excision of tumor tissue however, negatively affects the prognosis of the patient. In many cases, the presence of (microscopic) residual tumor tissue at the resection margins is a direct predictor of patient survival.
The completeness of tumor removal during surgery is dependent on the surgeon’s ability to differentiate tumor from normal tissue. Ideally, surgeons could use real-time information to detect tumors or positive resection margins during surgery. To accomplish radical excision of tumor tissue, radiotracers can be used that target tumor tissue and can be detected using a gamma probe during surgery. Yet, this technique cannot provide a precise delineation of the tumor and resection margins. The addition of a fluorescent label could help to overcome this limitation. Intraoperative fluorescence imaging could allow accurate real-time tumor delineation, but the penetration depth of emitted light in biological tissue is limited. So, a powerful synergy can be achieved by combining radiotracers for the detection of tumor tissue, and fluorescent tracers for subsequent accurate delineation of tumors.
Mark Rijpkema and colleagues are working on the development of new dual-labeled tracers and currently are implementing this into the clinic. For example, in patients with renal cell carcinoma, intraoperative dual-modality imaging is applied using girentuximab labeled with 111In and IRDye800CW. Similarly, in patients with peritoneal metastases of colorectal cancer we have started a study on radiodetection and fluorescence imaging during surgical resection.
The initial results show that both radionuclide detection and fluorescence imaging provide useful information to improve localization of tumors and radical excision of tumor tissue.