LoCAlly advanced and recurrent Rectal cancer NAVigationAL surgery 2.0

The current rate of incomplete resections in the treatment of locally advanced
and recurrent rectal carcinoma is unacceptably high: approximately a quarter
and over half of the resections, respectively. This results in a significant
risk of metastasis and has negative implications for life expectancy, quality
of life, healthcare efficiency, and medical capacity. Achieving a 'radical'
resection, where no tumor cells are left behind, is the key factor for
successful long-term survival.

Currently, surgeons determine the route for tumor removal prior to surgery
based on their analysis of magnetic resonance images (MRI), without guidance
during the operation. There is no available tool to check during surgery
whether all tumor cells have been removed.

After a thorough scientific preparation involving various studies, we have
currently treated 8 out of 10 intended patients at UMCG using image-guided
navigation according to the CARNAVAL 1.0 protocol (locally advanced and
recurrent rectal cancer navigation). In brief, before surgery, the tumor and
vital structures are highlighted in MRI images, and a plan is created. During
surgery, the tip of a rigid surgical instrument is calibrated, which can be
used by the surgeon in real-time and whose location is displayed on the scan
images to guide the surgeon according to the plan along the tumor and vital
structures. The preliminary results are promising. Particularly in cases of
locally advanced and recurrent rectal carcinoma, where the tumor has
infiltrated surrounding tissues and cannot be operated along anatomical planes,
there seems to be added value.

Within the framework of the CARNAVAL 2.0 project, this technique is applied to
a larger group of 30 patients by multiple surgeons. The primary goal of the
study is to determine the oncologic resection rate with a tumour-clear
resection margin and radical (R0, margin of >=1 mm) resection rate in patients
with a primary cT4bN0-2 locally advanced rectal or recurrent rectosigmoid
cancer whoand meeting the selection criteria, when optical stereotactic
navigation is applied in combination with 3D MRI topography is applied during
the oncologic resection. Theis results will be compared to those of a
historical case-matched cohort.
Secondary Objectives:
1) To determine the accuracy of optical stereotactic navigation defined by the
distance between the corresponding location in the scan when several anatomical
landmarks are pointed out by the surgeon using a tracked instrument and the
actual location of this anatomical landmark in the scan.
2) To optimize the workflow
3) To provide training to other rectal surgeons in the utilization of optical
stereotactic navigation combined with 3D MRI topography during oncologic
treatment for patients diagnosed with these tumors
4) To evaluate user satisfaction with this type of image-guided surgery

Monocenter, interventional, prospective, longitudinal clinical study.

Calibration of the position of the patient in the operating theatre and that of
the tip of a surgical instrument by using a c-arm.

The risks for the participating patients include:
- Extra radiation exposure of maximal 3.6 mSv (maximum of 3 3D runs c-arm).
- Reduced surgical precision in case of malfunctioning navigation system or
incorrect registration and unawareness by the surgeon with an associated
increased chance at iatrogenic injury or irradical resection.
However, with a yearly background radiation of ~2,5 mSv, 3.6 mSV is only a
limited amount of radiation and too small to demonstrate an association with
the occurrence of cancer or congenital defects. Additionally, the application
of surgical navigation systems are well expected to improve the quality of
surgery for rectal cancer as shown when used in other contexts, especially when
combined with 3D MRI-topography.