Treatment Modality for Colorectal Cancer

A 55 year old man is found to have isolated liver metastases at the time of primary surgery for colon cancer. What will be the most appropriate treatment for him?

• The liver metastases should be resected synchronously with colon cancer resection

• Liver biopsy should be obtained without liver resection

• Liver resection can be done after primary tumour resection

• Surgery for colon cancer should be abandoned as the cancer is now inoperable

Answer explanation

Normally, colorectal cancer resection & liver resection would not be performed synchronously. Lesions discovered at operation should not be biopsied. Patients with potentially resectable liver disease and who have undergone radical resection of the primary tumour should be considered for liver resection before consideration of chemotherapy. Patients with unfavourable primary pathology such as perforated primary tumour or extensive nodal involvement should be considered for adjuvant chemotherapy prior to liver resection and be restaged at three months. It has been argued that the limiting factor to the number of lesions that can be resected is whether it is technically possible to remove all tumours. Patients with solitary, multiple and bilobar metastatic disease are candidates for liver resection. The surgeon should define the acceptable residual functioning volume, approximately one third of the standard liver volume, or the equivalent of a minimum of two segments.

The following is accurate regarding the treatment of colorectal cancer.

• Surgical resection is recommended for all patients with stage IV disease

• Adjuvant chemotherapy is standard for patients with stage II disease

• Chemotherapy rather than surgery has been the standard management for patients with metastatic colorectal cancer

• Radiation therapy is standard for all patients with stage III disease

Answer explanation

Surgery is the only curative modality for localized colon cancer (stage I-III). Surgical resection potentially provides the only curative option for patients with limited metastatic disease in liver and/or lung (stage IV disease), but the proper use of elective colon resections in nonobstructed patients with stage IV disease is a source of continuing debate.

Adjuvant chemotherapy is standard for patients with stage III disease. Its use in stage II disease is controversial, with ongoing studies seeking to confirm which markers might identify patients who would benefit. At present, the role of radiation therapy is limited to palliative therapy for selected metastatic sites such as bone or brain metastases.

Chemotherapy rather than surgery has been the standard management for patients with metastatic colorectal cancer. Biologic agents have assumed a major role in the treatment of metastatic cases, with selection increasingly guided by genetic analysis of the tumor.

Part of the peri-operative management of a patient with low rectal cancer would include

• prophylactic antibiotics

• albumin infusion

• prophylaxis against deep vein thrombosis

• stoma counselling

The standard surgical operation for low rectal cancer is

• Hartmann’s procedure

• abdominoperineal resection

• total mesorectal excision

• transverse colostomy

In patients with Stage III colon cancer

• a referral should be made to an oncologist

• adjuvant radiotherapy is indicated

• PET scans can be used for routine follow-up

• CEA may be useful in monitoring the patients’ progress

In locally advanced rectal cancer

• a defunctioning ileostomy is the best option for treatment

• referral to a palliative care physician is appropriate

• 3rd line chemotherapy is indicated

• concurrent chemotherapy and radiotherapy is useful for down staging the tumour

Answer explanation

Defunctioning ileostomy is a surgical procedure adopted for fecal diversion in colorectal surgery to prevent the most important complication, i.e., anastomotic leakage

Features associated with poor prognosis in colorectal cancer include

• adenocarcinoma cell type

• rectal bleeding at presentation

• presence of involved lymph nodes

• lymphocytic response to tumour

Answer explanation

Mucinous rather than adenocarcinoma cell type, presence of involved lymph nodes and lack of lymphocytic response to tumour are features associated with poor prognosis. There is no association of rectal bleeding at presentation with poor prognosis

5 Fluorouracil based chemotherapy

• is indicated for all patients with Duke's B tumours

• in combination with capecitabine improves survival to around 18 months in metastatic disease

• is likely to impair quality of life when used in the metastatic setting

• improves 5 year survival rates for patients with Duke's C tumours by approximately 7%

Answer explanation

5 Fluorouracil (5FU) based chemotherapy improves 5 year survival rates for patients with Duke's C tumours by approximately 7%.

Its use in Duke's B disease is less well defined and chemotherapy tends to be offered only to those with tumours which exhibit other adverse prognostic features.

Capecitabine is an orally available prodrug of 5FU and is not used in combination with 5FU. Chemotherapy has been shown to confer a palliative benefit in patients with metastatic disease

Which of the following is a feature of colorectal cancer?

• In Duke's A disease >90% patients are cured by surgery alone

• Distant metastases are present in less than 5% of patients at presentation

• Chemotherapy has no effect on survival

• In Duke's C disease, patient can be cure via surgery

Answer explanation

In Duke's A disease >90% patients are cured by surgery alone whereas in Duke's C disease 5 year survival is 30-40%. There is a demonstrated survival advantage for 5FU based chemotherapy for patients with both Duke's C and metastatic disease. Approximately one third of patients have distant metastases at the time of presentation

Bevacizumab

• is a monoclonal antibody that targets vascular endothelial growth factor (VEGF)

• is a monoclonal antibody that targets epidermal growth factor receptor (EGFR)

• has no proven survival benefit in the metastatic setting

• is standard treatment for metastatic colorectal cancer

Answer explanation

Bevacizumab is a monoclonal antibody that targets vascular endothelial growth factor (VEGF). It has been shown to improve survival in the metastatic setting when used in combination with chemotherapy.

EGFR monoclonal antibodies- panitumumab and cetuximab