Focus on colon cancer

March is International Colorectal Cancer Awareness Month.

Worldwide, after lung and stomach cancer, colorectal cancer is the most common. Despite this, many people still detect it too late.

In Singapore, it is the top cancer killer of men and second for women. Every year, about 1,400 people get colorectal cancer here, and more than 600 die from it.

What are its symptoms and who are most at risk? When should you go for a screening?

Mind Your Body spoke to three colorectal experts for some answers.

They are: Dr Melissa Teo, a consultant in surgical oncology at the National Cancer Centre; Professor Adrian Leong, the deputy director and head of surgical oncology at the National University Cancer Institute; and Dr Peter Ang, a specialist in medical oncology at the OncoCare Cancer Centre.

Q: What is colorectal cancer and how does it occur?

Dr Teo: Most types of colorectal cancer arise from polyps which start out as benign or non-cancerous growths from the cells lining the inside of the colon or rectum. The change from being benign to becoming cancerous may take years but once a polyp becomes cancerous, it can grow and invade surrounding organs.

Q: What are the signs and symptoms of colorectal cancer?

Prof Leong: These will include blood in the stools, a change in bowel patterns, unexplained anaemia, abdominal pain and weight loss.

Q: Why is it usually detected late? Do the symptoms resemble other less serious conditions?

Dr Teo: Someone with colorectal cancer may be asymptomatic till the late stages of the disease, with only mild symptoms like lethargy and being easily fatigued after exertion.

Prof Leong: Patients may mistakenly attribute the blood they observe in their stools as coming from piles.

Q: Who are at highest risk?

Prof Leong: A family history of genetic disorders such as a tendency of getting multiple benign polyps which can later turn cancerous; or a genetic mutation that predisposes one to colorectal cancer even with little or no polyps, puts one at higher risk.

Other factors include a family or personal history of colorectal cancer or polyps, and ulcerative colitis, an inflammatory bowel condition.

Dr Ang: The risk from this cancer rises between the ages of 40 and 50; it increases with each decade after.

Q: Can colorectal cancer be prevented?

Prof Leong: The best preventive method currently is regular screening.

Dr Teo: Other methods of prevention include a healthy lifestyle; maintaining a normal body weight through physical activity; and a healthy diet of less red meat and more fruit and vegetables.

Dr Ang: Reducing alcohol intake and obesity are good starting measures to reduce the risk of colorectal cancer.

Q: What are the treatment methods and which are most often used?

Prof Leong: Surgery is the mainstay of treatment for colorectal cancer. Chemotherapy and/or radiation therapy is used in advanced cases.

Dr Ang: In advanced cancer, chemotherapy is the main form of treatment. New drugs have emerged recently, many of which have fewer of the side effects associated with chemotherapy such as hair loss or low blood count.

Q: What are the screening methods?

Prof Leong: The two most popular methods of colorectal cancer screening are faecal occult blood testing (FOBT) and colonoscopy.

Dr Ang: If occult blood is detected in the stools, a person needs to have an examination by colonoscopy, where a thin lighted tube is used to view the lining of the colon and rectum.

It does not mean that cancer is present when there is occult blood because factors such as gastric ulcers, diet, and medication like aspirin can give a positive result.

Polyps and early cancer may not bleed enough so screening has to be done yearly for it to be detected. In addition, the FOBT test is not suitable for those who already have bleeding piles.

Q: At what age should one have a first screening?

Dr Ang: Screening for average-risk individuals is from 50 years onwards but those at higher risk should do so earlier and have it more frequently. FOBT screening should be done yearly.

Q: What are the survival rates at the different stages, and can the cancer be nipped in the bud if caught early?

Dr Teo: In stage one of the disease, the cure rate is greater than 90 per cent. Seventy per cent to 80 per cent can still attain long-term survival in the early stages but for those in stages three and four, the average five-year survival rates are 40 per cent to 60 per cent and 10 per cent respectively. Hence, prevention is best but of equal importance is detection at the early stages, as colorectal cancer can be cured in these stages.

Q: Is colorectal cancer on the rise and why so?

Dr Teo: Colorectal cancer is the most common cancer here. Singapore has the highest age-standardised incidence rate of colorectal cancer in South-east Asia and this rate continues to increase at more than 2 per cent a year.

A similar trend is seen in many surrounding countries, as affluence brings about a change in environmental factors, diet and a more sedentary lifestyle, with incidence rates slowly approaching those of Western countries.

This article was first published in Mind Your Body, The Straits Times.