Lymph node recurrence after right colon resection for cancer: evidence for the utilisation of complete mesocolic excision

Abstract

Complete mesocolic excision (CME) of colon cancer is a resection performed along embryological planes to include the completely intact mesentery surrounding the tumour with a high central vascular ligation. The aim is to remove all lymph nodes draining the cancer. Proponents of the technique cite the significantly decreased local recurrence and improved 5-year survival rates associated with CME versus conventional colectomy. Although increasingly performed in many centres, it has not yet gained widespread acceptance as it is technically more challenging and can incur an increased bleeding risk. A man in his 80s underwent a conventional right hemicolectomy for a pT4aN2aM0 ascending colon cancer at another institution. This was followed by chemotherapy. He presented to our institution 2 years later with an isolated 3.7×3.2 cm mesenteric tumour adjacent to his anastomosis. There was no intraluminal recurrence. He then underwent a repeat extended right colectomy with CME. Pathology confirmed lymph node recurrence. His case demonstrates the importance of CME in reducing carcinoma recurrence risk.

Background

Colorectal cancer is the third most common cancer diagnosed worldwide with over 2 million new cases reported annually.¹ The surgical technique of complete mesocolic excision (CME) for colon cancer was first described in the mid-2000s and, more recently, is gaining widespread acceptance for its demonstrated impact on improving colon cancer survival. CME entails removing the cancer with its completely intact surrounding mesentery with a high vascular ligation. The aim is to excise all lymph nodes draining the cancer. It is not standard practice in many centres at this time, in part, due to its technically challenging nature, a variation in reproducible data and the potential for vessel damage and subsequent bleeding. However, several European and Asian centres have adopted the practice. This case of an isolated colon cancer recurrence in the mesentery only without intraluminal recurrence 2 years after a conventional hemicolectomy for colon cancer highlights the importance and utility of CME to decrease the risk of colon cancer recurrence.

Case presentation

A man in his 80s was referred from an outside institution with an isolated enlarged mesenteric nodule found on surveillance CT scanning. He had been diagnosed with carcinoma of the ascending colon at colonoscopy performed for anaemia 2 years previously. At that time, no metastases were found on staging. He underwent a right hemicolectomy at the outside institution. Pathology returned a pT4aN2aM0 poorly differentiated adenocarcinoma with signet ring features. All margins were free of disease (R0 resection). Four of 13 harvested lymph nodes were positive for tumour. Extranodal invasion was present. Postoperatively, he underwent adjuvant therapy with eight cycles of 5-FU+oxaliplatin. He was then entered into surveillance.

His medical history was pertinent for obesity, obstructive sleep apnoea, hypertension, chronic obstructive pulmonary disease, congestive cardiac failure and a pacemaker.

Investigations

The anastomosis from his previous conventional right hemicolectomy was visualised and there was no evidence of recurrence at the anastomosis or metachronous lesions found elsewhere during all routine surveillance colonoscopies. However, his 2-year postoperative routine surveillance, CT abdomen and pelvis demonstrated a 3.7×3.4 cm mass in the incompletely excised right mesocolon (ie mesentery) immediately below his ileocolic anastomosis, likely representing metastatic disease (figure 1). No other mesenteric or omental masses or ascites were seen. This was followed by a positron emission tomography (PET) scan, which demonstrated F-18 flourodeoxyglucose (FDG) avidity in the lesion. His case was discussed at our lower gastrointestinal multidisciplinary team meeting (GI MDT). The lesion’s FDG avidity made the diagnosis of carcinoma very likely. Due to its location behind several loops of small bowel, it was not amenable to biopsy. The decision was made to proceed to laparotomy and resection.

Figure 1.

An axial abdominal CT image demonstrating the patient’s isolated, markedly enlarged mesenteric mass.

He was asymptomatic at that time and denied any change to his bowel habit or weight loss. He was not anaemic. His carcinoembryonic antigen level was 1.9 ng/mL. It had been 6.2 ng/mL immediately prior to resection 2 years previously, fell to 2.9 postoperatively and had been consistently between 1.5 ng/mL and 1.9 ng/mL throughout his surveillance.

Differential diagnosis

The primary diagnosis was a lymph node recurrence of his colonic carcinoma. Other causes of mesenteric lesions include lymphadenopathy due to infectious causes (eg, infectious colitis, viral infection), inflammatory bowel disease and, relatively rarely, haematological malignancy (lymphoma). Duplication cysts and desmoid tumours can also be found in the mesentery. The size and proximity to his anastomosis for prior carcinoma were suggestive of proliferation of tumour cells within a lymph node, which was not excised during primary resection.

Treatment

After discussion at our GI MDT, he underwent an exploratory laparotomy. Intraoperatively, multiple adhesions between the small bowel loops were taken down to re-establish his anatomy. It was noted that recurrent tumour was present in the central right mesocolon, which had not been removed completely at primary surgery. The hepatic flexure was still preserved and it was noted that also the right branch of the middle colic artery was still in situ. This mass was comprised of recurrent tumour with multiple lymph nodes in the central mesocolon and was abutting the lower duodenum and infiltrating the mesosigmoid and sigmoid wall itself in its central area (figure 2).

Figure 2.

Intraoperative photo of the tumour from right mesocolon invading the sigmoid. The thick arrow points to the ascending colon with anastomosis. The thin arrow points to sigmoid colon. *Denotes the mesenteric tumour.

A CME was performed. The mobilisation of the right mesocolon was performed laterally towards medially until the superior mesenteric vein (SMV) was reached. The transverse colon was transected between the right and left branch of the middle colic vessels, which were all still present and intact. The ileum was freed up circumferentially at about 12 cm proximally to the ileocolic anastomosis and transected. The mesocolon and mesoileum were then gradually transected towards the central mesenteric vessels. The right branch of the middle colic artery and vein were clamped, transected and ligated. Dissection was then performed along the trunk of the middle colic artery towards the superior mesenteric artery (SMA) and SMV. From below, the SMV was reached along the mesoileum and the mesocolic dissection was performed centrally. The trunk of the ileocolic vein and artery was encountered, clamped, transected and ligated. A right colic artery was present, which was also clamped, transected and ligated. The gastrocolic trunk of Henle was also encountered and clamped, transected and ligated.

During the CME, the tumour was dissected off the duodenum. A Kocher manoeuvre was performed to free up the entire duodenum posteriorly and mobilise it in all three segments. The mass was then found to also invade the posterior retroperitoneum. The fatty tissue of the retroperitoneum between the aorta and ureter was dissected along with the tumour and included en bloc in the specimen. The omentum along the right transverse colon was dissected off and removed separately. The continuity of the bowel was restored by a new side-to-side ileocolic anastomosis using two linear staplers in a T-shape. Finally, the entire central mesocolic tissue was taken off the SMV and taken en bloc with the specimen to achieve an oncologic right hemicolectomy with CME. All enlarged lymph nodes and tumour tissue were removed in the mesocolon and healthy lymph nodes were taken further centrally with the specimen (figure 3).

Figure 3.

Pathological specimen with complete mesocolic excision. The thick arrow points to the vascular pedicle. The thin arrow points to the excised ileocolic anastomosis performed at initial, conventional, non-CME resection. CME, complete mesocolic excision.

A segmental sigmoid resection was then performed with margins of 5 cm proximally and 7 cm distally to the area of tumour invasion. A sigmoid mesocolic excision was performed at the mesosigmoid to include all tumour tissue. The continuity of the sigmoid colon was restored with a handsewn circumferential anastomosis using interrupted circumferential absorbable 3–0 Vicryl sutures. After removal of the specimen, the abdominal cavity was irrigated copiously. Haemostasis was performed using electrocautery. Estimated blood loss was 100 mL.

Outcome and follow-up

His postoperative course was uneventful. He was discharged home on day 5 postoperatively. On pathological evaluation, the mesenteric nodule was 6.3 cm in length and found to be surrounded by a dense fibrous reaction. Seventeen lymph nodes were found in the specimen. Metastatic adenocarcinoma was identified in one lymph node. The prior anastomotic site was intact and did not contain tumour.

The majority of the mesenteric tumour consisted of acellular mucin with a rim of lymphoid tissue indicative of a partially effaced lymph node. Numerous microscopic foci of tumour were seen within and around the mesenteric mass, consistent with nodal involvement of the patient’s prior colon adenocarcinoma with extranodal extension into the surrounding soft tissue. Surgical margins were negative.

His diverting ileostomy was reversed 3 months later. His last contact was 8 months postoperatively. His weight was stable and energy level improving.

Discussion

The principles of CME are based on the standard of care for rectal surgery, total mesorectal excision (TME). First described by Heald in 1982, TME entails excision of the rectum containing tumour with appropriate distal and proximal margins as well as the embryologically determined enveloping plane of connective tissue around the rectum (the mesorectum). Its use has dramatically reduced local recurrences and improved oncological outcomes.²

Popularised by Hohenberger et al, the principles surrounding CME of the colon are: (1) dissection between the mesenteric plane and parietal fascia and (2) the removal of the mesentery surrounding the tumour within a complete encasement of mesenteric fascia and visceral peritoneum. In theory, all lymph nodes draining the tumour should, therefore, be excised.^{3 4}

A central vascular tie to completely remove all lymph nodes in the central area is essential to the procedure. Additionally, an adequate length of bowel must be resected to remove all involved mesocolic lymph nodes in the longitudinal direction.⁵

Hohenberger et al’s original study reported a significant decrease in local recurrence (6.5% to 3.6%) and improved cancer-related 5-year survival in R0 patients with stage I–III cancers who underwent CME versus conventional colonic resection.³ Additionally, lymph node yield is significantly increased (from 18 to 30 in one study by West et al) in CME specimens.⁶ Opponents of the technique claim that CME may expose patients to a higher risk of surgical complications than conventional surgery. The technique involves increased risk to vessels including the SMV and SMA if not performed in a meticulous manner. Therefore, an understanding of the anatomy is essential.⁷ Systematic review has not demonstrated an increase in complications in the CME group.⁸ However, not surprisingly, a significantly longer operative time has been demonstrated in the CME group.⁹ CME has not yet been adopted into international guidelines; however, many centres, particularly in Asia and Europe, routine practice it.¹⁰

Our patient’s risk of recurrence may have been reduced if a CME had been performed initially. The presence of the right colic vessels, a long length of ileocolic vessels, a preserved hepatic flexure and cancer recurrence in the mesentery adjacent to the previous anastomosis support this. We were able to perform a CME as a salvage procedure with curative intent and have demonstrated it to be safe with acceptable blood loss. We were able to excise an additional 17 lymph nodes.

Learning points.

• Complete mesocolic excision (CME) dissection is performed between the mesenteric plane and parietal fascia with removal of the mesentery within a complete encasement of mesenteric fascia and visceral peritoneum and a high central vascular tie.

• In theory, all lymph nodes draining the tumour should, therefore, be excised.

• We present the case of a man in his 80s who had undergone a conventional/non-CME right hemicolectomy for cancer and experienced an isolated mesenteric lymph node recurrence 2 years later. He was curatively treated with a CME.

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