Colon Cancer

This is the second most common cancer among both men and women in Malaysia.

SYMPTOMS

These include a change in bowel habit over a period of weeks or months, rectal bleeding, abdominal pain, loss of appetite and weight loss and anaemia. Nausea and vomiting occasionally if bowel obstruction develops.

SCREENING & EARLY DETECTION

The ideal goal of screening would be to pick up early cancers that have no symptoms and this can lead to cure. Screening tools include faecal occult blood test (checking for the presence of small amounts of blood in the stool) or even better colonoscopy every 5-10 years. The use of tumour markers such CEA is not encouraged for routine screening. Tumour markers may only be raised when the tumour has reached a large size or even spread elsewhere (metastasized) and some cancers do not even produce markers. Therefore tumour markers may not be entirely reliable.

INITIAL ASSESSMENT

Tissue diagnosis is important so a biopsy needs to be done. After that, a staging scan should be done to check the extent of tumour, spread to nearby lymph nodes or to other organs such as liver or lungs.

STAGING SCAN

CXR + CT Abdomen & Pelvis

CT Chest, Abdomen & Pelvis

18FDG PET-CT

For recurrent cancers, staging scans will need to be repeated to assess the extent of cancer.

TREATMENT

SURGERY

Surgery plays a major role in the treatment for colon cancer. This usually takes the form of a colectomy which is removal of the affected part of the colon with a good margin >1cm of surrounding colon tissue. The colon can then be joined back together during the surgery or at a later date. It is also recommended to remove the lymph nodes surrounding the tumour. This is are usually found at the origin of the blood vessel that feeds the tumour. A minimum of 12 lymph nodes are required to be examined to establish the N (nodal) stage of the cancer.

This type of surgery can be done either laparoscopically (minimally invasive surgery) or via a traditional incisional cut on the surface of the abdomen (or known as “open” surgery). An experienced surgeon will be able to advise you which is the best option for you.

STAGE I

Surgery (usually a colectomy with removal of surrounding lymph nodes) will be the most appropriate treatment if the patient is medically fit for surgery.

The outcome is excellent and no further therapy is required after surgery.

STAGE II

Surgery (usually a colectomy with removal of surrounding lymph nodes) will be the most appropriate treatment if the patient is medically fit for surgery.

After surgery, it is important to see an oncologist to discuss the need for chemotherapy for deeper or larger tumours, poorly differentiated (more aggressive intrinsically), close surgical margins, less than 12 lymph nodes examined and/or invasion of cancer cells into the blood or lymphatic vessels in and around the tumour. The purpose of such chemotherapy is to mop up small numbers of cancer cells that may still be in the body.

Standard chemotherapy after surgery will include a fluoropyridimine drug eg 5 Fluorouracil or Capecitabine for 6 months. Less frequently oxaliplatin is added and will last up to 3 to 6 months.

STAGE III

Surgery (usually a colectomy with removal of surrounding lymph nodes) will be the most appropriate treatment if the patient is medically fit for surgery.

After surgery, a vast majority of patients will benefit from chemotherapy if they are fit enough to receive this treatment. The purpose of such chemotherapy is to mop up small numbers of cancer cells that may still be in the body.

Standard chemotherapy after surgery will include a fluoropyridimine drug eg 5 Fluorouracil or Capecitabine as well as Oxaliplatin. Chemotherapy given in this setting will typically last 6 months. Although in cases where the cancer is deemed not very severe, 3 months of treatment will suffice. There is no current evidence of benefit in adding on targeted agents or immunotherapy.

STAGE IV

Depending on the extent of cancer spread, a minority of patients may still be cured or otherwise have their lives extended for a long period. It is important to have a proper assessment and discussion with doctors from different specialties EG surgeon, oncologist, gastroenterologist and radiologist before deciding on management.

Depending on the general condition of the patient, the symptoms the patient is experiencing as well as the extent of spread to other organs, surgery might still be the most appropriate treatment if the patient is medically fit for surgery.

Early assessment of various genetic biomarkers (mutations) in the cancer cells is crucial. The important ones include KRAS, NRAS, BRAF and microsatellite instability (MSI). Other less common mutations may also be tested including HER2, NTRK etc. as there are treatment options available for such patients. Sometimes these extra genes can be tested for as part of a wider genomic profiling panel.

In patients who do not require surgery, these may proceed to systemic therapy. Modern systemic therapy typically includes chemotherapy as a “backbone”, with the option of adding targeted agents.

Chemotherapy backbone include FOLFOX, XELOX also called CAPOX, FOLFIRI, XELIRI or FOLFIRINOX regimes. eg Bevacizumab, Ramucirumab, Aflibercept, Cetuximab, Panitumumab and immunotherapy eg Pembrolizumab, depending on biomarker status. The precise sequence of the various combinations of systemic therapy may vary among oncologists.

For patients who have had several courses of systemic therapy and are sufficiently fit for further treatment, again it may be useful to have a repeat biopsy and this time to test for wider range of genetic mutations which may help the oncologist in selecting the most effective drugs for the next treatment.

For patients with limited areas of spread, surgery or other local ablative therapy eg radiofrequency ablation, cryotherapy, chemoembolisation, radioembolisation and precision radiotherapy, may be deemed appropriate to maximise control of the cancer. This may be recommended before or after systemic therapy.

There are patients who may decide not to proceed with active anti-cancer treatment or are otherwise unfit for treatment. Such patients will be offered best supportive care, to control symptoms and maintain the quality of life.