Surgery for colon cancer

Pre-operative considerations

Elderly patients should be screened for frailty using validated questionnaires. Formalised exercise tolerance tests (e.g., CEPEX) or stress echocardiography can be useful to further objectify increased risk. Medical optimisation of pre-existing cardiac or respiratory conditions should be considered promptly. Assessment of nutritional state, anaemia and lifestyle factors such as smoking must also be addressed. Patients with suspected malnutrition may benefit from high-calorie drinks pre-operatively. Intravenous iron or packed red blood cell transfusion, in severe cases, should be administered in cases of anaemia. ^, Smoking cessation must be encouraged, ideally at least 4 weeks before surgery, to avoid bronchial hypersecretion and normalise metabolic and immune function. Obese patients carry an increased risk of post-operative complications, but weight loss is often not feasible in the timeframe given in the cancer pathway. In selected cases of morbid obesity (BMI >40 kg/m ² ), radical diet or the insertion of a gastric balloon can be considered. Each patient should be assigned a point of contact, such as a cancer nurse specialist, pre-operatively to answer any questions going forward and facilitate timely management.

Enhanced recovery after surgery

ERAS includes over 20 different elements of peri-operative care; minimally invasive surgery to reduce post-operative pain and the use of opioids, early mobilisation and early oral intake are some of the most relevant factors in a surgeon’s practice. A detailed care protocol and informing patients about expected progression on a daily basis are equally important.

Pre-operative mechanical bowel preparation and oral antibiotics

The use of pre-operative mechanical bowel preparation and non-absorbable oral antibiotics, in addition to intravenous antibiotics 30–60 minutes before knife-to-skin, has been shown to significantly reduce the incidence of surgical site infection (SSI) in patients undergoing surgery for colorectal cancer. Large population-based, retrospective studies from the United States suggest that this regimen may be associated with lower anastomotic leak rates and ileus. The results of a randomised controlled trial including 417 patients from Finland however, did not show a reduction of SSI rates in patients undergoing colon resection.

Venous thromboembolism prophylaxis

The incidence of post-operative venous thromboembolism (VTE) in patients undergoing colorectal surgery has been reported as 1.1–2.5%. This risk is higher for patients with colorectal cancer.

Basic principles

Surgery remains the mainstay of treatment for localised colon cancer. The operation performed is defined by the location of the primary and the tumour is resected en bloc with the lymphatic drainage by ligation of the arterial supply to that section of colon. To achieve optimal oncologic outcomes, any adjacent organ involvement must also be resected en bloc.

Unlike in rectal cancer, where the optimal surgical technique, total mesorectal excision (TME), is well established and standardised, very few national guidelines describe the optimal surgical technique recommended for colonic cancer resections.

Specimen quality control

Resection specimens can be assessed regarding the completeness and the quality of the resection margins.

West et al. were the first to describe a grading system to assess the quality of colon cancer resection specimens based on the completeness of the mesocolic resection margin (mesocolic, intra-mesocolic and intramuscular) and demonstrated improved survival when surgery is performed in the ideal, mesocolic plane.

It was also shown that the correct plane of dissection is more often achieved in left-sided colon cancer resections compared with right-sided colon cancer resections. The length of the vascular pedicle is of limited use as it varies greatly between individual patients. A more recent grading system suggested by the German CME group also involves the completeness of the central extension of the mesocolic resection. Its clinical validation is yet to be shown ( Fig. 4.1 ).

Extent of lymphadenectomy

The optimal extent of lymphadenectomy remains controversial. Colonic lymph node basins can be classified according to their proximity to the tumour-containing segment of bowel and supplying vasculature. Epicolic and paracolic lymph nodes (within 5 cm of the tumour containing bowel) may be termed group 1 or N1 lymph nodes and are resected in a D1 resection. Intermediate lymph nodes (5–10 cm from the tumour bearing colon segment) are termed group 2 or N2 lymph nodes . A D2 colonic resection refers to the resection of both N1 and N2 lymph nodes en bloc. Central lymph nodes at the root of the named vasculature are termed N3 lymph nodes and are resected with a D3 colonic resection. Japanese guidelines recommend a D3 resection is performed for all patients with pre-operative radiological suspicion of node positive disease or for those tumours radiologically staged as T4 without obvious nodal involvement on computed tomography (CT). Patients with tumours that do not meet these criteria are offered a D2 resection. No such guidance on extent of lymphadenectomy is provided in European guidelines. A potential pitfall for selective use of D2/D3 resection based on pre-operative radiological staging is the inaccuracy of CT scans in determining accurately the depth of tumour invasion and the presence or absence of positive lymph nodes. In a meta-analysis by Nerad et al., the sensitivity and specificity of CT to distinguish between T1/T2 versus T3/T4 disease was 90% and 69% while the accuracy of prediction of lymph node involvement was only 78% and 68%, respectively ( Fig. 4.2 ).