Colorectal cancer – which affects the colon and rectum – was diagnosed in 5,383 men and 4,424 women in Singapore from 2011 to 2015, according to the Singapore Cancer Registry Annual Registry Report 2015. During this period, it was the most common cancer among Singaporean men, and was second only to breast cancer among Singaporean women.
According to the same publication, survival rates are also increasing, thanks to factors like advances in treatment and efforts to encourage screening so the disease can be detected earlier. Despite the relative prevalence of colorectal cancer, misconceptions about it still exist.
One common false belief about colorectal cancer is that it presents itself with accompanying symptoms.
In fact, more than half of diagnosed colorectal cancer patients display no symptoms, especially when the cancer is in its early stages.
If symptoms do present, they tend to be bowel-related, such as having altered bowel habits, an incomplete sensation when emptying the bowels, or blood in stool. Other symptoms include persistent abdominal pain or cramping, bloating or a sudden, unexplained weight loss.
While current cancer screening guidelines from the Ministry of Health (MOH) recommend that people begin colorectal cancer screening at the age of 50, new data has emerged showing increasing rates of colorectal cancer in younger people.
People who are at a higher risk of developing colorectal cancer are recommended to start screening sessions at an earlier age.
Dr Zee Ying Kiat, a senior consultant in medical oncology at Parkway Cancer Centre, defines higher risk individuals as those who have a strong family history or a personal history of colorectal cancer, or a long history of extensive inflammatory bowel disease. People with inherited conditions like familial adenomatous polyposis and Lynch Syndrome (a type of inherited-cancer syndrome) are also considered to be at a higher risk of developing colorectal cancer.
LIFESTYLE AND DIET
According to Dr Zee, smoking, drinking – even in moderation – and obesity all contribute to one’s chances of developing colorectal cancer.
A person’s diet is also a factor. “There is strong and consistent evidence that eating processed meat such as bacon, ham, sausages and luncheon meat increases colorectal cancer risk,” he said.
A World Health Organization group analysed data from over 800 studies and found that every 50g portion of processed meat – less than two slices of bacon – eaten daily increases the risk of colorectal cancer by 18 per cent.
Said Dr Zee: “While this data gives us good reason to reduce our intake of processed meats, it does not mean that we have to give it up entirely.”
Instead of processed meat, a bowl of oats would make a more nutritious breakfast choice. Dr Zee said: “The evidence of the protective effect of fibre has strengthened in the last few years. Overall, it shows that intake of dietary fibre – particularly from cereals and whole grains – reduces the risk of colorectal cancer.”
TREATING COLORECTAL CANCER
Another common misconception is that all colon polyps are cancerous. While those who are older, obese, smokers, or have a personal or family history of colorectal cancer are more likely to develop colon polyps, Dr Zee emphasises that only a small fraction of polyps develop into cancer.
“It takes years to happen,” he explained. “Polyps are quite common, with about one in four people having at least one polyp by the age of 50. But a polyp that is 1cm across has roughly a one-in-six chance of growing into a cancer over 10 years.”
Polyps can be detected during colonoscopy screenings for colorectal cancer, and may be removed during the colonoscopy with forceps or a wire loop, known as a polypectomy. Keyhole surgery can eliminate polyps that are too large or unsafe to remove using other techniques.
While the foundation of colorectal cancer treatment remains surgery, Dr Zee said that treatment may also include chemotherapy, radiotherapy, targeted therapy or cancer immunotherapy, depending on the patient’s health and how advanced the cancer is. About 75 per cent of Singaporean patients are diagnosed with Stage I, II or III colorectal cancer, meaning it has not spread to distant organs.
“The earlier colorectal cancer is diagnosed, the better the chance of survival,” said Dr Zee.
“Singapore has seen an overall increase in the survival rate of colorectal cancer over the years. This is largely reflective of the improvements in understanding, preventing and treating colorectal cancer.”
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