40 HOW TO TREAT: COLORECTAL CANCER: TREATMENT
40 HOW TO TREAT: COLORECTAL CANCER: TREATMENT
11 APRIL 2025 ausdoc. com. au
A B C
Huang X. World J Surg Oncol 2022 / CC BY 4.0 / bit. ly / 46RdAgm
Figure 4. Segmental colectomy. A. Segmental colectomy with D3 lymph node dissection. B. Right hemicolectomy with D3 lymph node dissection.
C. Segmental colectomy with extensive D3 lymph node dissection. Compared with operation A, an extensive apical lymph node dissection along the superior mesenteric vessels and its main branches is performed in operation C, while compared with operation B, the main vessels of the right-sided colon, ileocecal junction, and part of the ascending colon are preserved in operation C( if a right colic artery is too small, ligation is recommended). Anatomical pictures are from the Atlas of Human Anatomy. 2
PAGE 38 two weeks after surgery, however, 4-6 weeks is the norm. Surgeons generally advise patients to consume a low-residue diet to avoid a bolus obstruction of the anastomosis. Heavy lifting should be avoided for 4-6 weeks to reduce the risk of an incisional hernia. Patients are otherwise encouraged to mobilise and return to normal functioning as soon as comfortable. Postoperative physiotherapy and rehabilitation are appropriate for selected patients.
Prognosis and adjuvant therapy
Chemotherapy is integral in treating colorectal cancer where it is used to improve the cure rate in early-stage disease or prolong disease control in advanced disease. Multiple agents are active in colorectal cancer( see table 2).
Patients with stage I and favourable stage II disease are generally not offered adjuvant chemotherapy. Patients with unfavourable stage II disease may be offered adjuvant chemotherapy, typically with single-agent therapy. However, the demonstrated benefits in this setting are marginal, and this should only be offered after a detailed discussion with specialist oncologists. Detection of circulating tumour DNA in peripheral blood after surgery is a strategy currently being investigated to better identify which patients with stage II disease can be considered for adjuvant chemotherapy. 10 Most patients with stage III colonic cancer who are otherwise well are offered doublet( dual agent) chemotherapy. Traditionally, six months of adjuvant treatment was administered. Recently, however, a three-month program has been adopted as the standard for most patients with stage III disease, given the comparable survival outcomes and significantly reduced toxicity, especially peripheral neuropathy. 11
Palliative chemotherapy is generally offered to patients with stage IV disease to minimise the impact of systemic metastases, maintain quality of life and extend survival.
Fluoropyrimidines( cytotoxic agents) have long been the backbone of adjuvant chemotherapy regimens. Several early randomised trials established the role of adjuvant bolus fluorouracil( 5-FU) in combination with leucovorin( 5-FU / LV) as superior to surgical resection alone, significantly reducing mortality by 22-25 %. 12-14 Other studies focused on the role of infused 5-FU, which demonstrated improved tolerance with similar oncological outcomes over the bolus regimens, but less convenience because of the need to establish a venous access device.
Oral fluoropyrimidines, such as capecitabine, have been compared with 5-FU. Capecitabine undergoes a three-step enzymatic conversion to 5-FU, with the last step occurring in the tumour cell. The Adjuvant Colon Cancer Therapy study demonstrated that capecitabine was at least as effective as 5-FU / LV, with fewer side effects, other than hand – foot syndrome, also known as palmar-plantar erythrodysaesthesia. 15 Despite its increased convenience, capecitabine is not without its risks and close monitoring of patients is essential, especially in the elderly.
Oxaliplatin is the only platinum chemotherapy agent with activity in colorectal cancer. Having demonstrated activity in metastatic disease when combined with 5-FU / LV, it was subsequently investigated in adjuvant therapy trials. The large Multicenter International Study of Oxaliplatin / 5-FU / LV in the Adjuvant Treatment of Colon Cancer study assessed 5-FU / LV alone or with the addition of oxaliplatin( FOL- FOX) for six months among 2246 patients with resected stage II or III colon cancer. 16 The FOLFOX combination therapy was associated with improved overall survival. The benefit was confined to those with stage III disease, where a 4 % absolute improvement in survival at six years was reported.
Combination oxaliplatin with capecitabine, known as CAPOX or XELOX, has also been shown to be superior to 5-FU / LV in the adjuvant treatment of resected stage III
Figure 5. Intraoperative view( laparoscopic operation) of malignant tumour of sigmoid colon.
Box 3. Indications for a stoma
• Low rectal tumours requiring abdominoperineal resection and a permanent colostomy:— As outlined earlier, there are situations where rectal anastomosis may not be appropriate or possible on oncological or functional grounds where the tumour is close to the anal sphincters.
• Diverting loop ileostomy( see figure 8) for high-risk anastomoses:— While the risk of anastomotic leak may be in single digits, there are situations where the risk of leak may be higher.
• These include patients with obstruction or peritonitis, exposure to preoperative chemoradiation, low rectal anastomosis or emergency surgery.
• In these cases, instead of forming a colostomy, a loop ileostomy may be created to protect the downstream anastomosis. This is because a future reversal of this loop ileostomy can often be performed with a peristomal incision, which is technically less challenging.
• Colostomy for high-risk anastomoses:
— In certain situations, the risk or consequences of an anastomotic leak may be too high to even consider diversion and primary anastomosis. In these situations, a colostomy will be formed and the distal end stapled off.
— Although these are possibly reversible, the technical challenge and magnitude of the subsequent operation may preclude future restoration of bowel continuity.
• Anastomotic leakage:— Regardless of the level of expertise of the treating clinicians and maximisation of surgical technique, a small number of patients will have anastomotic leakage after a primary colorectal anastomosis.— Under these circumstances, if a return to the operating theatre is required, most patients will require the formation of a temporary ileostomy or colostomy.
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