Importance: Carcinoma of Unknown Primary (CUP) presents a clinical challenge for practitioners. The current diagnostic approach often involves extensive imaging and examinations, with variable success. We aimed to evaluate the effectiveness of Indocyanine Green (ICG) injection using the Da Vinci robot to aid in intra-operative detection of primary tumors.
Objectives: To evaluate the diagnostic utility of ICG use during robotic surgery to aid in either the identification of the primary tumor or delineate the extent of disease to guide ablation
Methods: This study involved a retrospective review of patients treated at the Massachusetts Eye and Ear who underwent robotic surgery with the utilization of Indocyanine Green (ICG) for the identification of a primary tumor since November 1, 2022. All patients in the study were operated on using the SP model of the Da Vinci robot. Basic demographic and pathologic data were recorded. Intraoperative data points included assessing the presence of an identifiable primary tumor using white light only and documenting the confidence level of ICG localization.
Results: In total, 28 patients who underwent robotic surgery using ICG were identified for this study. The mean age of the cohort was 62 years. Twenty-six patients were male, and the primary diagnosis was HPV related squamous cell carcinoma (SCC) in 22 cases, HPV negative SCC in 5 cases, atypia in 1 case, and metastatic papillary thyroid carcinoma in 1 case. Nine patients had either PET localizing or visually identified primary tumor, and ICG was used to guide surgical extent of resection. The remaining 19 patients had CUP. Within the patients with CUP, ICG was utilized in all cases, and the primary was ultimately identified in 16 of the 19 (84.2%) cases. . This resulted in a True Positive detection in 10 cases (52.6%), False Positive detection in 6 cases (31.6%), False Negative detection in 0 cases (0%), and True Negative detection in 3 cases (15.8%). Based on a confusion matrix of the aforementioned values, the calculated sensitivity, specificity, PPV, and NPV were 100%, 33.3%, 62.5%, and 100%, respectively. The discriminatory index of ICG in detection of unknown primary disease was found to be 66.6%.
Conclusion: The integration of ICG fluorescence with the Da Vinci SP robot's real-time imaging capabilities is a valuable adjunct for enhancing primary tumor identification in CUP patients as well as guiding the extent of surgery in select patients.