Randomized comparison of near-infrared fluorescence lymphatic tracers for sentinel lymph node mapping of cervical cancer

Antibody-based imaging strategies for cancer

Although mainly developed for preclinical research and therapeutic use, antibodies have high antigen specificity, which can be used as a courier to selectively deliver a diagnostic probe or therapeutic agent to cancer. It is generally accepted that the optimal antigen for imaging will depend on both the expression in the tumor relative to normal tissue and the homogeneity of expression throughout the tumor mass and between patients. For the purpose of diagnostic imaging, novel antibodies can be developed to target antigens for disease detection, or current FDA-approved antibodies can be repurposed with the covalent addition of an imaging probe. Reuse of therapeutic antibodies for diagnostic purposes reduces translational costs since the safety profile of the antibody is well defined and the agent is already available under conditions suitable for human use. In this review, we will explore a wide range of antibodies and imaging modalities that are being translated to the clinic for cancer identification and surgical treatment.

Molecular imaging of prostate cancer: translating molecular biology approaches into the clinical realm

The epidemiology of prostate cancer has dramatically changed since the introduction of prostate-specific antigen (PSA) screening in the 1980's. Most prostate cancers today are detected at early stages of the disease and are considered 'indolent'; however, some patients' prostate cancers demonstrate a more aggressive behaviour which leads to rapid progression and death. Increasing understanding of the biology underlying the heterogeneity that characterises this disease has led to a continuously evolving role of imaging in the management of prostate cancer. Functional and metabolic imaging techniques are gaining importance as the impact on the therapeutic paradigm has shifted from structural tumour detection alone to distinguishing patients with indolent tumours that can be managed conservatively (e.g., by active surveillance) from patients with more aggressive tumours that may require definitive treatment with surgery or radiation. In this review, we discuss advanced imaging techniques that allow direct visualisation of molecular interactions relevant to prostate cancer and their potential for translation to the clinical setting in the near future. The potential use of imaging to follow molecular events during drug therapy as well as the use of imaging agents for therapeutic purposes will also be discussed.

KEY POINTS

• Advanced imaging techniques allow direct visualisation of molecular interactions in prostate cancer. • MRI/PET, optical and Cerenkov imaging facilitate the translation of molecular biology. • Multiple compounds targeting PSMA expression are currently undergoing clinical translation. • Other targets (e.g., PSA, prostate-stem cell antigen, GRPR) are in development.

Sentinel node biopsy for lymph nodal staging of uterine cervix cancer: a systematic review and meta-analysis of the pertinent literature

BACKGROUND

We reviewed the available literature on the accuracy of sentinel node mapping in the lymph nodal staging of uterine cervical cancers.

METHODS

MEDLINE and Scopus were searched by using "sentinel AND (cervix OR cervical)" as key words. Studies evaluating the accuracy of sentinel node mapping in the lymph nodal staging of uterine cervical cancers were included if enough data could be extracted for calculation of detection rate and/or sensitivity.

RESULTS

Sixty-seven studies were included in the systematic review. Pooled detection rate was 89.2% [95% CI: 86.3-91.6]. Pooled sensitivity was 90% [95% CI: 88-92]. Sentinel node detection rate and sensitivity were related to mapping method (blue dye, radiotracer, or both) and history of pre-operative neoadjuvant chemotherapy. Sensitivity was higher in patients with bilaterally detected pelvic sentinel nodes compared to those with unilateral sentinel nodes. Lymphatic mapping could identify sentinel nodes outside the routine lymphadenectomy limits.

CONCLUSION

Sentinel node mapping is an accurate method for the assessment of lymph nodal involvement in uterine cervical cancers. Selection of a population with small tumor size and lower stage will ensure the lowest false negative rate. Lymphatic mapping can also detect sentinel nodes outside of routine lymphadenectomy areas providing additional histological information which can improve the staging. Further studies are needed to explore the impact of sentinel node mapping in fertility sparing surgery and in patients with history of neoadjuvant chemotherapy.

Sentinel-lymph-node procedures in early stage cervical cancer: a systematic review and meta-analysis

We performed a meta-analysis to assess the accuracy of sentinel-lymph-node (SLN) procedures for the assessment of nodal metastases in patients with early stage cervical cancer. Studies of SLN procedures for detecting nodal metastases in patients with early stage cervical cancer were systematically searched in MEDLINE and EMBASE between January 1, 2000 and August 30, 2013. We identified 49 eligible studies, which included 2,476 SLN procedures. The mean overall weighted-detection rate was 0.93 (95 % CI 0.92–0.94), at a pooled sensitivity of 0.88 (95 % CI 0.84–0.90) with limited heterogeneity (χ² = 80.57, degrees of freedom = 47, p = 0.002). Subgroup analysis of sensitivity and the rate of detection of different tracer techniques and surgery methods used in conjunction with an SLN procedures were as follows: studies using combined techniques, 0.88 (95 % CI 0.84–0.91) and 0.97 (95 % CI 0.96–0.98); studies using metastable technetium-99, 0.87 (95 % CI 0.78–0.93) and 0.90 (95 % CI 0.87–0.93); studies using blue dye, 0.87 (95 % CI 0.79–0.93) and 0.87 (95 % CI 0.84–0.90); studies using laparotomy, 0.86 (95 % CI 0.80–0.90) and 0.87 (95 % CI 0.83–0.91); studies using laparoscopy, 0.90 (95 % CI 0.86–0.94) and 0.93 (95 % CI 0.90–0.96); and studies using robot-assisted surgery, 0.84 (95 % CI 0.72–0.92) and 0.92 (95 % CI 0.88–0.95). We concluded that the SLN procedure performs well diagnostically for the assessment of nodal metastases in patients with early stage cervical cancer.

Fluorescent imaging of cancerous tissues for targeted surgery

To maximize tumor excision and minimize collateral damage are the primary goals of cancer surgery. Emerging molecular imaging techniques have made "image-guided surgery" developed into "molecular imaging-guided surgery", which is termed as "targeted surgery" in this review. Consequently, the precision of surgery can be advanced from tissue-scale to molecule-scale, enabling "targeted surgery" to be a component of "targeted therapy". Evidence from numerous experimental and clinical studies has demonstrated significant benefits of fluorescent imaging in targeted surgery with preoperative molecular diagnostic screening. Fluorescent imaging can help to improve intraoperative staging and enable more radical cytoreduction, detect obscure tumor lesions in special organs, highlight tumor margins, better map lymph node metastases, and identify important normal structures intraoperatively. Though limited tissue penetration of fluorescent imaging and tumor heterogeneity are two major hurdles for current targeted surgery, multimodality imaging and multiplex imaging may provide potential solutions to overcome these issues, respectively. Moreover, though many fluorescent imaging techniques and probes have been investigated, targeted surgery remains at a proof-of-principle stage. The impact of fluorescent imaging on cancer surgery will likely be realized through persistent interdisciplinary amalgamation of research in diverse fields.

Intraoperative imaging-guided cancer surgery: from current fluorescence molecular imaging methods to future multi-modality imaging technology

Cancer is a major threat to human health. Diagnosis and treatment using precision medicine is expected to be an effective method for preventing the initiation and progression of cancer. Although anatomical and functional imaging techniques such as radiography, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET) have played an important role for accurate preoperative diagnostics, for the most part these techniques cannot be applied intraoperatively. Optical molecular imaging is a promising technique that provides a high degree of sensitivity and specificity in tumor margin detection. Furthermore, existing clinical applications have proven that optical molecular imaging is a powerful intraoperative tool for guiding surgeons performing precision procedures, thus enabling radical resection and improved survival rates. However, detection depth limitation exists in optical molecular imaging methods and further breakthroughs from optical to multi-modality intraoperative imaging methods are needed to develop more extensive and comprehensive intraoperative applications. Here, we review the current intraoperative optical molecular imaging technologies, focusing on contrast agents and surgical navigation systems, and then discuss the future prospects of multi-modality imaging technology for intraoperative imaging-guided cancer surgery.

Real-time near-infrared fluorescence guided surgery in gynecologic oncology: a review of the current state of the art

Near-infrared (NIR) fluorescence imaging has emerged as a promising complimentary technique for intraoperative visualization of tumor tissue, lymph nodes and vital structures. In this review, the current applications and future opportunities of NIR fluorescence imaging in gynecologic oncology are summarized. Several studies indicate that intraoperative sentinel lymph node identification in vulvar cancer using NIR fluorescence imaging outperforms blue dye staining and provides real-time intraoperative imaging of sentinel lymph nodes. NIR fluorescence imaging can penetrate through several millimeters of tissue, revealing structures just below the tissue surface. Hereby, iatrogenic damage to vital structures, such as the ureter or nerves may be avoided by identification using NIR fluorescence imaging. Tumor-targeted probes are currently being developed and have the potential to improve surgical outcomes of cytoreductive and staging procedures, in particular in ovarian cancer. Research in the near future will be necessary to determine whether this technology has additional value in order to facilitate the surgical procedure, reduce morbidity and improve disease-free and overall survival.

Sentinel lymph node evaluation in women with cervical cancer

Lymph node status is the most important prognosticator of survival in women with early stage cervical cancer. Thus many patients with cervical cancer will undergo pelvic lymphadenectomy as part of the treatment. This procedure is associated with substantial morbidity. Use of the sentinel lymph node technique in women with cervical cancer has the potential to decrease this morbidity. Multiple studies have suggested that sentinel lymph node mapping in these patients is feasible, with excellent detection rates and sensitivity. This review examines the current body of literature about sentinel lymph node biopsy in women with cervical cancer.

Image-guided cancer surgery using near-infrared fluorescence

Paradigm shifts in surgery arise when surgeons are empowered to perform surgery faster, better and less expensively than current standards. Optical imaging that exploits invisible near-infrared (NIR) fluorescent light (700-900 nm) has the potential to improve cancer surgery outcomes, minimize the time patients are under anaesthesia and lower health-care costs largely by way of its improved contrast and depth of tissue penetration relative to visible light. Accordingly, the past few years have witnessed an explosion of proof-of-concept clinical trials in the field. In this Review, we introduce the concept of NIR fluorescence imaging for cancer surgery, examine the clinical trial literature to date and outline the key issues pertaining to imaging system and contrast agent optimization. Although NIR seems to be superior to many traditional imaging techniques, its incorporation into routine care of patients with cancer depends on rigorous clinical trials and validation studies.

Near-infrared fluorescence sentinel lymph node biopsy in vulvar cancer: a randomised comparison of lymphatic tracers

This study aims to confirm the feasibility of near-infrared (NIR) fluorescence imaging for sentinel lymph node (SLN) biopsy in vulvar cancer and to compare the tracer indocyanine green (ICG) bound to human serum albumin (HSA) versus ICG alone. Women received 99mTc-nanocolloid and patent blue for SLN detection. Subsequently, women randomly received ICG:HSA or ICG alone. In 24 women, 35 SLNs were intraoperatively detected. All SLNs detected were radioactive and NIR fluorescent and 27 (77%) were blue. No significant difference was found between ICG:HSA and ICG alone. This trial confirms the feasibility of NIR fluorescence imaging for SLN mapping in vulvar cancer.

Near infrared fluorescence for image-guided surgery

Near infrared (NIR) image-guided surgery holds great promise for improved surgical outcomes. A number of NIR image-guided surgical systems are currently in preclinical and clinical development with a few approved for limited clinical use. In order to wield the full power of NIR image-guided surgery, clinically available tissue and disease specific NIR fluorophores with high signal to background ratio are necessary. In the current review, the status of NIR image-guided surgery is discussed along with the desired chemical and biological properties of NIR fluorophores. Lastly, tissue and disease targeting strategies for NIR fluorophores are reviewed.