Early screenings can help prevent colon cancer

PUBLISHED : Monday, 15 July, 2013, 12:00am
UPDATED : Monday, 15 July, 2013, 9:47am

Erica had never considered herself at risk of colorectal cancer before 2006, and was unaware it was one of Hong Kong's biggest cancer killers. But after her mother died from colon cancer in 2006, Erica decided to undergo screening.

In January 2008, she was diagnosed with the same cancer that had killed her mother. Alarmingly, despite the absence of symptoms, it was at an advanced stage and had already spread to her liver.

Hong Kong has become more prosperous, the incidence rate has increased
Professor Yuen Siu-tsan

"I was devastated," recalls Erica, now aged 50. "My son was only 12 years old, and as my mother had died so quickly, I thought I would not live to see him go to secondary school."

In 2010, there were 4,370 new cases of colorectal cancer, the Hong Kong Cancer Registry says. It is one of the most common cancers in Hong Kong, second only to lung cancer in men, and breast cancer in women.

Thirty years ago, it was much less common, with only 818 cases in 1983. But since then the number has risen by about 3 per cent a year. It caused 1,864 deaths in 2010.

According to Professor Yuen Siu-tsan, medical adviser to the Hong Kong Cancer Fund, the city's growing prosperity has led people to switch to a diet rich in red meat, animal fats and processed food. This is to blame for the dramatic increase in colorectal cancer.

"Colorectal cancer is a disease of wealthy societies. When Hong Kong was less developed, the incidence rate was much lower. But as Hong Kong has become more prosperous, the incidence rate has increased," says An honorary clinical professor in the department of pathology at University of Hong Kong, Yuen says as many of 85 per cent of cases were sporadic and believed to environmentally linked to diet and lifestyle.

"With lung cancer on the decline, it is only a matter of time before colorectal cancer overtakes it to become the number one killer cancer in Hong Kong," says Yuen.

Ironically, colorectal cancer is one of the most easily preventable. Screening can detect abnormalities before they become cancerous. Building public awareness of the disease has become a priority of the Hong Kong Cancer Fund.

A spokesman for the fund says the message is that lifestyle changes can help reduce the risk of developing the disease, and early detection saves lives.

Two types of screening are available: a non-invasive method called faecal occult blood test and a colonoscopy. The blood test involves examining stool samples for blood produced by growths in the colon. But it needs to be done regularly and is not capable of detecting abnormal growths at a precancerous stage.

According to Professor Law Wai-lun, a clinical professor in the department of surgery at University of Hong Kong's Li Ka Shing Faculty of Medicine, this is why the colonoscopy is considered the gold standard for investigations of the colon.

Like most experts, Law recommends people consider screening with this method at the age of 50, and then every 10 years afterwards.

With a colonoscopy, the colon is screened using a flexible tube fitted with an endoscopic high-definition camera passed through the whole colon via the rectum. There is also a version called a sigmoidoscopy which just screens the lower bowel.

This method, which can be performed as a day case under mild sedation, allows cancer to be detected at very early stages. It also effectively prevents it by detecting it at a pre-cancerous stage as abnormal growths called polyps, which can develop into cancer over 10 to 15 years.

Many experts are calling for a government screening programme offering colonoscopies to people over the age of 50. This would help early diagnoses which, in turn, could save lives and prevent people like Erica undergoing the trauma of treatment.

With hindsight, Erica wishes she had heard about colonoscopies earlier in her life. Her own battle with cancer spanned three years and included chemotherapy, three surgical procedures, and targeted therapy. But she is now clear, and takes comfort that her experience inspired her two siblings to have a colonoscopy.