Novel intraoperative near-infrared fluorescence camera system for optical image-guided cancer surgery.

Current methods of intraoperative tumor margin detection using palpation and visual inspection frequently result in incomplete resections, which is an important problem in surgical oncology. Therefore, real-time visualization of cancer cells is needed to increase the number of patients with a complete tumor resection. For this purpose, near-infrared fluorescence (NIRF) imaging is a promising technique. Here we describe a novel, handheld, intraoperative NIRF camera system equipped with a 690 nm laser; we validated its utility in detecting and guiding resection of cancer tissues in two syngeneic rat models. The camera system was calibrated using an activated cathepsin-sensing probe (ProSense, VisEn Medical, Woburn, MA). Fluorescence intensity was strongly correlated with increased activated-probe concentration (R2= .997). During the intraoperative experiments, a camera exposure time of 10 ms was used, which provided the optimal tumor to background ratio. Primary mammary tumors (n = 20 tumors) were successfully resected under direct fluorescence guidance. The tumor to background ratio was 2.34 using ProSense680 at 10 ms camera exposure time. The background fluorescence of abdominal organs, in particular liver and kidney, was high, thereby limiting the ability to detect peritoneal metastases with cathepsin-sensing probes in these regions. In conclusion, we demonstrated the technical performance of this new camera system and its intraoperative utility in guiding resection of tumors.

p53 and HLA class-I expression are not down-regulated in colorectal cancer liver metastases.

p53 overexpression occurs in more than 50% of colorectal carcinomas, which makes it an interesting target for immunotherapy. HLA class I expression on tumor cells is required for the presentation of p53 peptides and an effective T-cell mediated-immune response to ensue. To analyze to which extent p53 and HLA-I expression in a primary tumor reflects expression in liver metastases, we investigated p53, HLA-A and HLA-B/C expression in 82 colorectal carcinomas and 143 associated liver metastases of 82 patients. We used the monoclonal antibodies DO-7 (p53), HCA2 (HLA-A) and HC-10 (HLA-B/C) on formalin-fixed, paraffin embedded tissue. The percentage of expressing cells was estimated. P53 was overexpressed in 73% of the colorectal carcinomas and 66% of liver metastases. HLA-A was expressed in 98% and 96% and HLA-B/C in 100% and 94% of colorectal cancers and liver metastases respectively. There were no significant differences between the primary tumors and the liver metastases for each marker. The concordance was also very high in those cases in which more than one metastasis was available. Discordant cases consisted of tumors in which expression of p53 or HLA-A was lost in the liver metastases, whereas it was present in only a few tumor cells in the primary tumor. The combined analysis of p53 and HLA-I expression in liver metastases demonstrated that both molecules were expressed in 63% of the cases. P53 and HLA-I were expressed in the majority of primary tumors and their associated liver metastases. This allows to select patients for p53-immunotherapy on the basis of p53 and HLA-I expression in the primary tumor.