Personalised surgery for the colon cancer patients: new frontiers

Introduction

The large bowel is divided into the colon, and the lower part called the rectum and anus. Cancer might develop any place in the large bowel, and usually cancer in the colon or rectum develop from the same type of intestinal cells.

Until the late 1980’s cancer in the rectum typically had a worse prognosis than in the colon. Then, new operative techniques were introduced, and gradually a new understanding of the rectal anatomy developed which led to improvement of the prognosis.

Modern laparoscopic techniques for colon cancer surgery came later. It was not until about 15 years ago that these techniques were introduced in the West, having previously been advocated in Japan. These modern techniques required surgeon awareness of the vascular anatomy¹.

Colon cancer develops in the large bowel but might spread to different organs through blood vessels supplying the tumour area or through lymph vessels following these blood vessels². These pathways need to be removed together with the tumour. Equally important, is to ensure that the remaining bowel is well vascularised after removal of the tumour. Therefore, surgeons need to know the vascular anatomy.

3D models

The 3D printing technology today is advanced enough to make reliable and detailed 3D models of any patient’s blood vessels. The patients all have a CT scan before elective colon cancer surgery. This scan can be used to make advanced 3D virtual reconstructions and then print-ready files for physical 3D models^{3, 4}. Our research group has shown that 3D physical models are a reliable and accurate way to replicate the patient’s anatomy.

We believe that awareness of the individual vascular anatomy before surgery helps deliver personalised and safe surgery.

In our latest articles we have in detail examined the splenic flexure vascular supply in 32 patients, using 3D physical and virtual models. The splenic flexure is a part of the colon fixed in the area of the spleen. This is a difficult area to operate in because the arteries come from two different main vascular territories, established very early in the embryological development, both coming from different origins in the foetal life⁵.

The blood vessels

The main arteries are always present. From the right, the splenic flexure gets its blood supply from the middle colic artery (MCA). This artery usually originates from the superior mesenteric artery (SMA) which originates from the aorta. The MCA bifurcates and the left branch goes towards the splenic flexure. In addition to the ordinary MCA, an accessory (additional) MCA is present in about 1/3 of the patients. Whenever present, it represents an extra pathway for lymphatic spread.

 From the left the splenic flexure is supplied by another main artery, the inferior mesenteric artery (IMA) arising directly form the aorta. Between the origin of the IMA to the origin of the MCA there is a three-dimensional relationship (a difference in level) that we refer to as “the mesenteric inter-arterial stair” (Figure 1). When it is necessary to remove the central lymph nodes in a patient, this difference in level is a challenge and knowledge of the anatomy of this area is crucial.

We have found that the inferior mesenteric vein (IMV) follows the border of “the mesenteric inter-arterial stair”. The surgeon can use this knowledge when attempting to remove the central nodes of the above mentioned both embryological vascular areas by using the IMV as a guide.

Conclusion

Our research clarifies the three-dimensional relationship found between the origins of the IMA and the MCA.  The surgeon should attempt to connect these two vascular areas by following the IMV. Since the splenic flexure is supplied from two different vascular areas, lymphatic spread might occur in multiple directions. The surgeon requires comprehensive knowledge of the patient’s individual vascular anatomy, and the preoperative CT 3D reconstructions, and in addition 3D physical models could be helpful.