Page 117 - Fluorescence-guided cancer surgery

Imaging based on the EPR e ect in ovarian cancer 115
INTRODUCTION
Ovarian cancer has a worldwide incidence of 225,500 making it the 6th most common cancer in women. With 140,200 deaths worldwide per year, it has the highest mortality rates amongst all gynaecological cancers1-3. In general, ovarian cancer can be classi ed as early stage (FIGO I to IIa) or advanced stage (FIGO IIb to IV). Prognosis and treatment are mainly dependent on this classi cation.
Early stage ovarian cancer has a 5 year survival of 75-100%, with the most important factors in uencing survival being di erentiation grade of the tumor and the completeness of staging1. During surgical staging, blind biopsy samples of prede ned areas and biopsy samples of suspected lesions are obtained. The primary aim of the staging procedure is to determine whether there is occult metastatic disease not primarily visible by the naked eye. When no metastases are present, resection of the primary tumor is the treatment of choice and chemotherapy can be avoided4. When metastases are present, surgical resection is supplemented with chemotherapy. Optimal staging has been shown to improve survival in low stage ovarian cancer because it discriminates true early stage ovarian cancer from occult tumor spread, which results in more advanced disease4.
However, most patients (around 75%) present with advanced disease5. The most important prognostic factor for overall survival in advanced stage disease is the amount of residual tumor after cytoreductive surgery6-8. Therefore complete cytoreduction, de ned as no visible residual tumor left after surgery, or optimal cytoreduction, not consistently de ned as a maximal diameter of residual tumor of 0-2 cm5;9-11, is the goal for advanced stage ovarian cancer surgery.
In order to achieve either optimal staging or complete or optimal cytoreduction, visualization of tumor lesions is of great importance. With imaging modalities such as CT and MRI, pre-operative identi cation and localization of tumor lesions is reasonably achievable, however intraoperative visualization of tumor tissue can be challenging.
Near-infrared (NIR) uorescence imaging is a promising technique to assist in the real time intraoperative identi cation of malignant lesions12. This technique makes use of NIR uorescent light (700-900 nm) emitted by contrast agents after excitation by an imaging system able to detect this NIR uorescent