Colorectal Cancer

Screening & Diagnostics Tests In Colorectal Cancer

These are some of the steps followed for diagnosing colon cancer:

Screening for colorectal cancers: Screening is sometimes conducted for individuals over the age of 50 and may involve examination for Faecal Occult Blood Test (traces of blood in the stool that may not be seen) and a colonoscopy.

Clinical History & Examination: The clinician will conduct a clinical history for symptoms such as changes in bowel habits, abdominal pain and discomfort, recent history of unexplained weight loss and fatigue. The physical examination will include an abdomen examination, to look for swelling and pain, and a digital rectal examination using a finger of a gloved hand to examine the interior of the anus and the rectum.
Routine blood tests: These include complete blood count, liver function and kidney function tests. These tests often provide signs of colorectal cancer and spread of the cancer to other organs.

Endoscopy: A thin tube with a camera is inserted through the anus into the large intestine to inspect the bowel for abnormal growths and/or to perform a biopsy for histopathological examination by the pathologist. There are various terms used by the clinicians for different types of endoscopy based on what part of the intestine is examined: rectum only (rectoscopy), lowest part of the large intestine, above the rectum (sigmoidoscopy) and the entire large intestine (colonoscopy). During your endoscopy, the doctor may also take tissue samples for biopsy. A pathologist examines this sample from a biopsy under a microscope to confirm the diagnosis of colorectal cancer and reveal specific characteristics of the tumour.
Radiological Test: Barium enema - This test involves the use of barium sulphate to visualize an outline of the wall of the colon and rectum. Computed Tomography (CT) - Using a CT colonography, a 3-dimensional image of the interior wall of the large intestine is formed. It is useful when a colonoscopy is difficult. A CT of the chest and the abdomen may be performed to detect the metastatic spread of the tumour. Ultrasound - An ultrasound is used to search for the spread of cancer, especially to the liver, or for fluid in the abdomen. Magnetic resonance imaging (MRI)- An MRI is useful to detect or confirm the presence of metastases (spread of cancer) as well as staging of the colorectal cancer. Positron emission tomography (PET)- It is performed to detect metastases (spread of cancer in the body).
Carcinoembryonic antigen (CEA): CEA is a protein found in many types of cells. CEA can be tested through a blood test. CEA is also known as a tumour marker because it may be useful in some situations when the cancer cells produce the CEA. CEA testing is useful for evaluation of prognosis and follow-up after treatment.
Molecular profiling: This are tests that study the entire set of genes or analyse the tumour for chemicals released by a particular gene. These are sometimes used to tailor the chemotherapy to improve the response. that one may hear include RAS mutations, BRAF mutation, MLH1 mutation, chromosomal instability and microsatellite instability etc.

Additional Videos about Testing

Colon Cancer Treatments

The management of cancer depends on various factors, including the stage of cancer, additional health issues, age etc. Surgery, radiation or chemotherapy may be used. Following are some of the steps followed for colon cancer treatments:

• Surgery: The surgeon aims to remove the primary tumour and, in advanced cases, to remove metastatic lesions. The type of colon cancer surgery performed depends on how advanced the cancer is. It may be Simple excision (tumour is removed from the inner layer of the bowel wall), polypectomy (if the cancer develops from a polyp, the entire polyp is removed), segmental resection (a section of bowel is surgically removed, and the two cut ends are reconnected). Depending on the section removed the surgeries are named differently: ascending colon removed (right hemicolectomy), descending colon removed (left hemicolectomy), sigmoid colon removed (sigmoid resection), right and left hemicolectomy extended to the transverse colon (extended hemicolectomy). Anastomosis is the procedure which connects the two cut ends of the bowel after resection.
  In certain patients, a temporary outlet directly to the abdomen (bypassing the rectum and anus) may need to be created called a stoma. If it involves the small intestine, it is called ileostomy, and a stoma procedure of the large intestine is called colostomy. In some cancer the surgeon may put a stent (tube) if the cancer is obstructing the colon. Minimally invasive procedures are used in early-stage disease such as Endoscopic mucosal resection (removal of polyps along with the inner lining of the colon removed during colonoscopy). Laparoscopic surgery can be indicated for polyps that can't be removed during a colonoscopy using a key-hole size excision and inserting cameras in the abdomen along with surgical instruments.
  In rectal cancer, the entire rectum, along with the lymph node associated with it is removed. This procedure is called total mesorectal excision. Side effects: Adverse events of surgery for rectal cancer may include intestinal symptoms (such as pain, diarrhoea, constipation and nausea), intestinal obstruction (a surgical emergency in which the intestine is blocked and the obstruction need to relieved immediately).

• Chemotherapy: Colon cancer chemotherapy is given orally or through a vein and kills the cancer cells systemically. Various agents may be used and can be given as single therapy (monotherapy), or in combination with other drugs (combination therapy). Side effects: The most frequent side effects experienced with chemotherapy include anaemia, bleeding, bruising, infections, fatigue, nausea or vomiting, diarrhoea, mouth ulcers, reddening of the palms and soles, skin rashes, muscle cramps, abdominal pain etc.

• Radiotherapy: Radiotherapy destroys tumour cells using ionizing irradiation and may be used alone or in combination with chemotherapy, especially prior to surgery or post-surgery in selected patients. Radiotherapy may be external source radiotherapy or internal radiation (brachytherapy), which involves injecting tiny microspheres or radioactive material into arteries that supply the tumour. Side effects: Adverse effects of radiotherapy may include rectal discomfort, diarrhea, mucus and blood in the stool, painful urination, blood in urine etc.

• Targeted drug treatments: These agents block specific chemical pathways present in cancer cells. It is usually combined with chemotherapy and is typically reserved for people with advanced colon cancer. Side effects: The adverse effects depend on the agent used but common side effects include rashes, allergic reactions, headaches, fatigue, hypertension, diarrhoea etc.
• Immunotherapy: Immunotherapy uses the body’s immune system to fight against cancer cells. Your body’s immune system may not attack cancer because the cancer cells produce proteins that blind the immune system cells from recognising cancer cells and prevent their destruction. Immunotherapy works by interfering with this process. It is usually reserved for patients with advanced colon cancer.
• Proton beam therapy: This is one of the latest advances in colorectal cancer treatment that may benefit young adults and patients with cancers close to critical organs. Proton Beam Therapy allows radiation oncologists to destroy cancer and spare healthy tissue.
  Supportive (palliative) care: Palliative care focuses on providing relief for the patient and caregiver, especially from pain, anxiety and other symptoms. The key objective is to improve the quality of life for people with cancer and their families.

Sources: European Society for Medical Oncology (ESMO); Mayo Clinic;