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Colorectal cancer (or cancer of the large bowel) is the second leading cause of cancer-related death in the western world. The average person has a 1 in 20 chance of developing colorectal cancer throughout their lifetime. This translates into around 30,000 new cases in the UK each year. Although colorectal cancer can occur at any age, more than 90% is found in people over the age of 40, the risk increases with age and most people diagnosed in their 50’s or 60’s.

Diagnosing colorectal cancer is a challenge. Early cancers or pre-cancerous lesions known as polyps are often asymptomatic, whilst many cancers present with symptoms which are attributed to common conditions such as piles or a stomach bug.

General symptoms which should alert suspicion include; rectal bleeding, an alteration in bowel habit, abdominal pain and weight loss, however patients with the following are considered to be at particularly high risk of having a cancer and should be referred to a colorectal surgeon without delay;

• Rectal bleeding and a change in bowels towards looser/more frequent stools for 6 weeks in those aged 40 or over
• Rectal bleeding without anal symptoms for 6 weeks in those 60 or over
• A change in bowels towards looser/more frequent stools for 6 weeks in those aged 60 or over
• Patients with a mass in the right side of their abdomen
• Men of any age with iron deficiency anaemia (haemoglobin <11g/100mls)
• Non-menstruating women with iron deficiency anaemia (haemoglobin <10g/100mls)
   

Is colorectal cancer preventable?

Most colon and rectal cancers develop from a single cell and become a non cancerous (benign) growth known as a polyp. This grows slowly and eventually become a cancer. The challenge for doctors is to identify cancers in their early or pre-cancerous stage. Polyps appear as projections inside the colon and can usually be removed by colonoscopy, the government is introducing a screening program for those between the ages of 60 and 70 to try to identify those who may have a polyp or early cancer (see colorectal cancer follow up and screening).

Dietary modification may reduce the risk of developing colorectal cancer although the precise benefit remains unclear. Increasing fibre intake by eating more fruits, vegetables and whole grains and reducing your intake of fats and refined foods will certainly reduce the overall risk of developing cancer in addition to reducing the risk of heart disease, diverticular disease, constipation and piles. Some studies have demonstrated a slightly reduced risk of developing polyps in groups taking aspirin or calcium supplements but again the impact in the population is unclear.


What is the difference between benign and cancerous growths?

Cancer is unique in that cells can spread into other organs, benign growths cannot do this. Cancers can spread by direct growth of the tumour into nearby organs such as the abdominal wall, other loops of bowel, the bladder and prostate (in men) or uterus and vagina (in women). Distant spread may occur when cells break away from the main tumour. These are called metastases and may travel through the blood steam or through the lymph fluid which bathes the cells. These metastasis often lodge in lymph glands. The commonest sites of distant spread for colorectal cancer are lymph glands, the liver and the lungs.

How are cancers of the colon and rectum treated?

The treatment of these cancers has undergone major changes over the last few years. Although the mainstay of therapy remains to surgically remove the cancer the introduction of newer chemotherapy drugs and the benefits of radiotherapy mean that many patients who would have had a limited life expectancy in the past can be offered the chance of a cure. Cancers occurring in the rectum (the lower 15cms of bowel) may be greatly reduced in size by chemotherapy and radiotherapy before surgery is undertaken (this is known as “neo-adjuvant” therapy).

Newer surgical techniques have dramatically reduced the risk of the cancer returning in many cases, and reduced the likelihood of needing a permanent stoma. The advent of laparoscopic colorectal surgery means that patients may avoid large abdominal incisions, recover from surgery far quicker and have less post-operative pain. Operations to remove metastasis from the liver and lungs, although not suitable for everyone, are now commonplace and achieve long term survival in up to a third of people.

Following surgery newer chemotherapy drugs have been shown to improve survival considerably in those with cancer that has spread to the lymph glands (this is known as adjuvant therapy). Due to wide array of treatment options your case will be discussed by your surgeon at a multidisciplinary meeting which consists of a variety of other doctors who specialise in cancer therapy. Following general agreement in this meeting, your surgeon will explain your further management to you in detail usually with the help of a nurse who specialises in this field.


What is “staging”?

Before any treatment plan is decided, you will undergo a variety of investigations including blood tests, a colonoscopy, a CT scan of your chest and abdomen (and an MRI scan if you have a rectal cancer). This allows your surgeon to evaluate the extent of the tumour and tailor treatment as appropriate. After surgery, the cancer is sent to a pathologist who will examine it using microscopic techniques to see;

• How far it has grown into the bowel wall
• If it has spread into nearby lymph nodes
• The degree of differentiation (how similar to normal cells the cancer cells of this particular tumour are).

Estimates of long-term survival relate directly to the stage of the disease. Patients in whom the caner is limited to the bowel wall and does not involve the lymph nodes, have an excellent outlook. Those in which the cancer has spread to other areas or involves the lymph nodes have an increased risk that the cancer may return however the chance for cure is significantly improved by additional treatment such as chemotherapy, radiotherapy or even further surgery.

Follow-up

After surgery patients under go a special follow up to make sure that, should the cancer return, it is identified early giving the best chance of cure (see colorectal cancer follow up and screening). If a cancer does recur they tend to do so within the first 2 years following surgery however, follow up is traditionally continued for 5 years before cure can be confidently declared.