Keeping your nerve - Artificial intelligence-based surgical navigation aims to improve quality of life for patients with rectal cancer

Tumor operations in the rectum are performed along a millimeter-thin layer that borders on important nerves. If these are damaged, it can lead to incontinence and sexual dysfunction. Scientists at the National Center for Tumor Diseases Dresden (NCT/UCC) and the Else Kröner Fresenius Center (EKFZ) for Digital Health are therefore developing a computer-based assistance system that will use artificial intelligence to significantly reduce the risk of such complications. "We expect this to significantly improve the quality of many tumor operations in the rectal area in the future," says Prof. Jürgen Weitz, one of the managing directors at the NCT/UCC on the occasion of Colorectal Cancer Month in March. A current study is also investigating how often and to what extent patients are affected by continence and potency problems.

The National Center for Tumor Diseases Dresden (NCT/UCC) is a joint institution of the German Cancer Research Center (DKFZ), the University Hospital Carl Gustav Carus Dresden, Carl Gustav Carus Faculty of Medicine at TU Dresden and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR).

A good 58,000 people in Germany are diagnosed with colorectal cancer every year. About one third of them suffer from a tumor in the rectum. For the majority of patients, surgery is the most important treatment option. If the tumor can be completely removed, a permanent cure is possible. However, in addition to the successful treatment of the cancer, the subsequent quality of life of those affected also plays an important role. "When removing tumors in the rectum, a few millimeters are crucial. If the surgeon cuts too close to the tumor, he may not remove everything. If he cuts too far away, surrounding nerves can be damaged. The consequences are then bladder or fecal incontinence, erection problems or other sexual problems such as insensitivity during sexual intercourse," says Prof. Jürgen Weitz, Director of the Clinic for Visceral, Thoracic and Vascular Surgery (VTG) at the University Hospital Carl Gustav Carus Dresden and Managing Director at the National Center for Tumor Diseases Dresden (NCT/UCC).

Tumor surgery in the rectal region has made significant progress in recent years: highly precise surgical techniques have been further refined and standardized. In many cases, surgery can be performed without a large abdominal incision, which improves wound healing and shortens hospital stays. Robotic methods are also possible here. At the Clinic for Visceral, Thoracic and Vascular Surgery at Dresden University Hospital, around 60 rectal cancer operations are performed each year, the vast majority of which are carried out with the aid of the "Da Vinci" robotic assistance system. The device relieves the surgeon of the need to hold and move instruments directly and translates larger hand movements, which the surgeon executes via two joystick-like handles, into tiny tremor-free incisions. "Despite these excellent capabilities, the experience of the individual surgeon still largely determines the quality of the procedure. Our ambition is to support the surgeon even more in his difficult task in the future and to increase the quality of treatment across the board," says Prof. Weitz.

Intelligent system provides situational assistance

Scientists at the NCT/UCC, VTG Surgery at Dresden University Hospital and the Faculty of Electrical Engineering and Information Technology at TU Dresden are therefore developing a computer-based assistance system for robot-assisted rectal surgery in the "CoBot" project funded by the EKFZ. In the application, the surgeon will see the camera images from the patient's abdomen during the operation while looking at the monitor as usual. If necessary, the system will superimpose additional information on the camera images: for example, the location of important nerves or the optimal incision line. "It is particularly important that the right information is available at the right time. The surgeon makes the decisions himself at all times. The system only supports him, similar to a navigation system in a car," explains Prof. Stefanie Speidel, head of the Translational Surgical Oncology Unit at the NCT/UCC.

To develop the system, the scientists use an artificial neural network, which, as a subfield of artificial intelligence, mimics the ability of humans to learn from examples. They provide the intelligent algorithm with the following mathematically formulated task: Based on the continuous analysis of the video images of an operation, special structures are to be displayed in certain phases of the operation. So far, they have trained the neural network with around 40 surgical videos, which were recorded as standard via an optical instrument (laparoscope) in the abdominal cavity. In each of the videos, which could be up to ten hours long, central surgical phases, nerves to be spared and the narrow area where cutting is allowed were marked. "In the coming months, we will feed the system with more data. Next year, it will then be tested in real operations as part of a study," says Dr. Fiona Kolbinger, clinical project manager from the Clinic for Visceral, Thoracic and Vascular Surgery and Clinician Scientist at the EKFZ.

Gentle therapy for a better quality of life

In view of improved therapies, risks of serious side effects can also be reduced by gentle treatment concepts. This is because impaired continence and sexual function can be caused not only by surgery but also by radiation therapy. In the case of smaller tumors that have not yet penetrated deep tissue layers, it is possible to dispense with initial radiation therapy to reduce the size of the tumor. In the case of larger tumors, on the other hand, surgery may not be necessary at all in some cases if the tumor disappears completely as a result of radiation chemotherapy. These patients are then monitored very closely to see if the tumor returns. "In order to find the best individual solution, at the NCT/UCC expert committees made up of specialists from various disciplines - known as tumor boards - discuss the best possible treatment for each individual. This is extremely important in order to embed the modern concepts into the overall treatment strategy, including the latest developments in diagnostics and drug treatment, " says Prof. Gunnar Folprecht. The colorectal cancer specialist heads the Department of Oncology at Medical Clinic I of Dresden University Hospital.
Current studies on continence and potency problems are lacking. Earlier studies showed that up to 50 percent of patients after rectal cancer surgery suffer long-term from severe fecal incontinence and about 30 percent from sexual functional limitations. A study at VTG Surgery is currently investigating how often and to what extent patients are affected by these side effects, even in view of the latest treatment options. Around 400 rectal cancer patients who have undergone surgery at VTG Surgery at Dresden University Hospital since 2013, as well as all patients operated on with this diagnosis in the future, can take part in this study. "Based on the results of the study, in the future it will also be a matter of providing patients with even more targeted advice and suitable aftercare options. In addition, we want to bring the quality of life of patients with rectal cancer more into the focus of scientific discussion and initiate further research into improved therapies," says Dr. Kolbinger.

Press contact:
Dr. Anna Kraft
Nationales Centrum für Tumorerkrankungen Dresden (NCT/UCC)
Presse- und Öffentlichkeitsarbeit
Tel.: +49 (0)351 458-5548
E-mail: anna.kraft@nct-dresden.de
www.nct-dresden.de