Sentinel node dissection has the potential to solve a big dilemma in endometrial cancer treatment. Potentially it can resolve the question as to whether to remove lymph nodes to determine the extent of the disease and how many nodes to remove. Potentially we can spare ourselves frozen section examinations, which are both time consuming and sometimes unreliable.
At present, two major technologies are commercially available for sentinel node dissection in Australia and I have been fortunate enough to test both systems recently.
I was fortunate to have the opportunity to test the Novadaq system at the end of last year and the Stryker 1588 system recently.
Both systems rely on Indocyanine Green (ICG) injected into the cervix immediately prior to the procedure. ICG is not TGA approved for sentinel node studies but the surgeon can apply for an exemption (TGA Category A Form Special Access Scheme). The surgeon only needs to provide the patient’s initials AND one of either date of birth, age, gender or MRN). ICG is TGA approved for vascular studies, hepatic function studies and ophthalmic angiography studies. Adverse events are rare.
Novadaq Pinpoint Endoscopic Fluorescence Imaging System
While Novadaq came to Australia only a few years ago, its system is used in North America for several years and many of my colleagues in the US and in Canada use it for sentinel node biopsy in endometrial and cervical cancer as a matter of routine. Virtually all data presented to date in scientific papers or at conferences on sentinel node biopsy for endometrial cancer have been generated with the Pinpoint system.
For laparoscopic sentinel node dissection, the surgeon will open the retroperitoneal spaces and identify bright-green node(s). Sometimes, very fine lymphatic channels are visible here that lead the surgeon to the node(s) in question. Most of the time the node(s) will be located in the space underneath the external iliac vein. However, in my very first case that I did with the Pinpoint system the ICG technique and fine green lymphatic channels led me to a sentinel node that was located in the lower aortic area that I could have easily missed if I would not have used the sentinel node technique.
On the Pinpoint camera head the user can switch between several different view modes but only 2 modes are essential, the “normal” white-light laparoscopic and the ICG “fluorescence” mode. The ICG mode allows visualisation of the sentinel node against a clear, white-light background. I could switch from ICG to “normal” mode through buttons on the camera head when I was dissecting the iliac vessels and the ureter switch and back to ICG mode if I wanted to see the sentinel node(s) highlighted.
I tested the Novadaq system late in 2016 and I believe a newer version of a camera is available now. However, back then, the camera was slightly heavier than the laparoscopic camera heads that I normally work with. At the time of testing, only a 10-mm scope was available but Novadaq apparently brought a 5-mm scope to market in the meantime. The other thing I had to get used to was that the user needs to press up and down buttons to focus the image; there is no reel to put the image in focus. Additional buttons were available to toggle between the different view modes, which was very easy to do.
The stack comes with a 26” LED screen, a Pinpoint camera and scopes (10 mm or 5 mm, 0 degree or 30 degree), an insufflator, a video processor unit, and a video recorder. It can be used across multiple surgical specialties for “ordinary” laparoscopic or endoscopic cases also.
The Pinpoint system is marketed also be used for colorectal surgery (to test the blood supply of the colonic anastomosis and to reduce the anastomotic leak rate), in oesophagectomy and bariatric surgery and data are encouraging for nipple-sparing breast reconstructive surgery.
In Australia, Novadaq is represented by Surgicore and Conmed.
The Stryker 1588 system
Stryker has been the incumbent provider of laparoscopic technology in Australia for many years. Given their strength in orthopaedic surgery, they only brought their advanced imaging technology to market in December 2015 in the US and in January 2017 in Australia.
The 1588 system has five advanced imaging modalities of which, for the aim of sentinel node biopsy, we will only use two; a normal “Clarity” mode which and the ICG mode (Endoscopic Near-infrared Visualisation mode) that will highlight the sentinel node. The background of the image is dark; however, the brightness of the node as well as the background’s brightness (darkness) can be modified.
In our case, we were delayed with the sentinel node dissection because my patient had severe omental adhesions to the anterior abdominal wall, which took 40 minutes to dissect. Then, the intensity of the image was extraordinarily good. We saw the sentinel node even through the peritoneum of the lateral pelvic wall shining through. We opened the lateral pelvic wall and checking transperitoneally, it was very easy to find the sentinel node.
The camera has the form, shape, and weight of a usual Stryker camera head. We used a 5-mm, zero-degree scope, which is what I normally use for all my laparoscopic cases. The camera can be put in focus using a wheel on the camera head. There are multiple view modes to choose from and it was very easy to toggle between different light sources.
Integrated into the 1588 Stryker system is an additional functionality to highlight the ureters. I have not used this myself yet but it seems that ureteric catheters can be connected to the light source of the Stryker stack, which will highlight the ureter(s) in challenging cases with distorted anatomy.
Like the Pinpoint system, the Stryker 1588 system can also be used across multiple surgical specialties without the need for a specific ‘sentinel node biopsy’ stack. It can also be integrated into an existing Stryker laparoscopic stack. The light source, scopes, and the camera system would require upgrade/exchange, which would be more cost friendly compared to buying a whole new system.
In Australia, some hospitals and health care operators will have agreements with Stryker products in place already and the purchase process would be easier. In Australia, Stryker has an extensive network of representation.
In summary, we now have two excellent technological platforms available for sentinel node biopsy in gynaecological cancer. Until now I regularly struggled making a decision whether to remove lymph nodes as part of the surgical staging and how aggressively I should remove nodes.
With the advent of sentinel node technology, we will be able to provide better surgical care to patients and save hospital operators money because we now don’t need to waste time waiting for frozen section results.