How to spot symptoms of colorectal cancer, the second most common cancer in Hong Kong

Many Hongkongers do not bother screening and ignore symptoms such as cramps and rectal bleeding, putting themselves at risk of this killer disease

PUBLISHED : Monday, 14 December, 2015, 5:30am
UPDATED : Monday, 14 December, 2015, 5:30am

Routine colon cancer screening has been proven to save lives, but people often avoid getting tested because of the unpleasant procedure.

By snaking a camera through a patient’s intestines – a procedure called a colonoscopy – doctors can identify colon cancer in its infancy and remove the polyps and other abnormal growths before they eventually become cancerous.

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There could soon be a less invasive and cheaper alternative screening method to the uncomfortable and invasive colonoscopy. It could induce encourage more people to get tested: a simple blood test.

Researchers at Canada’s BC Cancer Agency, collaborating Fujian Normal University scientists, have identified differences in the blood of people with precancerous polyps compared to people without such polyps. The researchers say the initial results are promising, but the procedure is still in the research phase and must go through additional lab tests and clinical trials before implementation.

For now, the other non-invasive colon cancer screening mechanism available is the faecal occult blood test, which looks for microscopic traces of blood in stool samples, a potential sign of cancer. However, many early-stage colon cancers are asymptomatic and don’t bleed, leaving them undetectable by this measure.

According to the Department of Health’s Centre for Health Protection, colorectal cancer is the second most common cancer in Hong Kong. Yet, many young people do not think they need to be screened for it, or they ignore the early symptoms of the disease.

See Hong Kong urged to start colon cancer tests from the age of 50

From the age of 50, both men and women are at an average risk for developing this cancer and should undergo screening tests to rule out the disease, says Dr Victor Hsue Chan-chee, president of the Hong Kong Association of Community Oncologists.

Hsue says while more than 50 per cent of colorectal cancer cases were diagnosed in patients aged 65 and over in 2012, the disease was also found to be prevalent in patients aged 45 to 64, with about one-third of cases coming from this age group. Less than five per cent of new diagnoses were from the under-45 age group. Of the cases diagnosed in Hong Kong that year, 4,653 were men and 1,903 were women.

Dr David Chow, resident consultant, and specialist in gastroenterology and hepatology at Matilda International Hospital, says older people are at a higher risk for developing colorectal cancer. The risk rises after the age of 45 and is higher in males.

Chow says a family history or colon polyps or colorectal cancer is a very important pointer, particularly if the cancer sufferers are first-degree relatives, such as parents or siblings. If you have an underlying bowel disease, such as inflammatory bowel disease, you may have an increased risk.

Besides age and family or personal history, other factors that can raise risk of colorectal cancer include excessive alcohol consumption, smoking, and obesity. High consumption of red meat or processed meat, a low fibre intake, and a lack of exercise have also been associated with the disease.

“Screening detects cancer or precancerous lesions before the patient has any symptoms,” Chow says. “Since colon polyps are known to be the precursor of most colorectal cancers, early detection and removal of the polyps have been proven to be useful. When the cancer is detected earlier it saves lives, because patients in this early stage have a higher chance of being cured.”

Some early symptoms of colorectal cancer include a change in bowel habits, including diarrhoea or constipation, or a change in the consistency of stools; rectal bleeding or blood in stools; persistent abdominal cramps, gas or pain; a feeling that the bowel has not emptied completely; weakness, fatigue and unexplained weight loss.

When the cancer is detected earlier it saves lives, because patients in this early stage have a higher chance of being cured
David Chow, specialist in gastroenterology and hepatology

If you experience any of these symptoms, you should seek medical advice immediately. But, even if you do not have any symptoms, Chow advises getting screened for colorectal cancer from the age of 50 – earlier if there is a family history of the disease.

“The simplest screening test is the faecal occult blood test,” says Chow. “This should be done annually. If the result comes back positive, you should have further tests, such as a colonoscopy.

“There is also a test called sigmoidoscopy, which should be done every five years. Though still recommended, it is not favoured among experts since it looks at only a portion of the colon.”

A colonoscopy is considered to be the most accurate test, as it enables the doctor to look at the patient’s colon directly and to remove any polyps. Chow says that a colonoscopy should be carried out every 10 years, and more frequently if the patient has polyps.

A colonoscopy might sound scary, but Hsue says serious complications from this test, such as tears in the colon lining, bleeding and blood clots are rare, and tend to occur more often in older patients.

To minimise your risk of developing colorectal cancer, Hsue suggests being more physically active, since a lack of exercise is thought to be associated with the disease.

A diet that is low in fat, high in fibre, and mostly vegetarian, is also thought to help lower one’s risk, although this is still disputed.

“Some studies have shown that a diet high in fat, protein, calories and meat increases the risk of colorectal cancer, but other studies have shown different results,” says Chow.

Just a brief change in diet has been shown to affect one’s colon cancer risk. African-Americans and Africans who swapped their typical diets for just two weeks similarly exchanged their respective risks of colon cancer as reflected by alterations of their gut bacteria, according to an international study led by the University of Pittsburgh School of Medicine published in April in Nature Communications.

According to the study’s principal investigator Dr Stephen O’Keefe, increasing the amount of fibre in the diet – from approximately 10 grams to more than 50 grams for African-Americans – likely led to biomarker changes reflecting reduced cancer risk. Eating less animal fat and proteins could also be helpful.

“These findings are really very good news,” says O’Keefe. “In just two weeks, a change from a Westernised composition to a traditional African high-fibre, low-fat diet reduced these biomarkers of cancer risk, indicating that it is never too late to modify the risk of colon cancer.”