Colorectal cancer (CRC) is the most commonly diagnosed cancer and biggest killer in Singapore, affecting more than 1,800 people each year regardless of gender and ethnicity. Unfortunately, many do not experience any symptoms in the early stages, resulting in a delayed diagnosis that is much more difficult to treat.

The risk of developing CRC depends on numerous risk factors, though many are linked to our diet and lifestyle habits. The more risk factors that are present, the higher the risks of developing the disease.

Low fibre intake - CRC risk increases by 65%

The IARC, the cancer research arm of the WHO, has classified processed meat as "carcinogenic to humans" and red meat as "probably carcinogenic to humans". Daily intake of 50g processed meat and 100g are positively associated with 17% and 12% increased risk of CRC respectively.

On a low fibre diet (insufficient consumption of fruit and vegetables), for example, consuming less than 1.5 servings per day, the risk of developing CRC would increase by 65% when compared against a daily intake of 2.5 servings of fruit and vegetables.

Advice

Decrease consumption of red and processed meat; at least five servings of fruit and vegetables a day.

Overweight and Obesity - CRC risk increases by 42%

Excessive body fat can increase the levels of certain hormones (such as insulin) that stimulates the body’s inflammatory response, promoting the development of CRC. Overweight and obese individuals, central obesity (waist circumference in men over 36 inches and 32 inches in women) in particular, would increase the risk of early-onset CRC by 42%.

Advice

Maintain a healthy BMI between 18.5 and 22.9, and a waist circumference of below 90 cm (~ 36 inches) for men and below 80 cm (~32 inches) for women.

Smoking - CRC risk increases by 14%

With at least 69 known carcinogens in a cigarette, IARC has classified tobacco smoking as “carcinogenic to humans” . Compared to non-smokers, current smokers have a 14% increased CRC risk. Additionally, the higher the smoking frequency and duration, the higher the risk of developing CRC.

Advice

Avoid or quit smoking.

Alcohol consumption - CRC increases by 10%

Alcohol consumption increases the risk of CRC. The consumption of alcoholic beverages is classified by IARC as “carcinogenic to humans”. Alcoholic beverages (including beer, wine and liquor) contain numerous toxic compounds, including ethanol and its metabolite acetaldehyde that can be carcinogenic. Drinking 1–2 alcoholic drinks per day is associated with 10% increased risk of CRC.

Advice

Avoid alcohol drinks.

Lack of physical activity - CRC risk increases by 7%

A sedentary lifestyle or job is a risk factor for CRC. Indulging in an extra two hours of TV a day can increase the risk by 7%, or sitting at a desk by 4%. Furthermore, an increase of two hours of total sitting time per day was associated with a 2% increment in the risk of developing CRC.

Advice

Take part in moderate intensity aerobic physical activity for at least 150 minutes (2 hours and 30 minutes) a week.

References：

Awareness and Prevention of Colorectal Cancer. HKSAR. 31 Jan 2022. Retrieved from https://www.change4health.gov.hk/en/whats_new/ncd_watch/20220131.html

Wild CP, Weider pass E, Steward B W, (Eds). World Cancer Report.: Cancer Research for Cancer Prevention. Lyon, France: International Agency for Research on Cancer, 2020.

Cho YA, Lee J, Oh J H, et al. Genetic risk score, combined lifestyle factors and risk of colorectal cancer. Cancer Research and Treatment 2019;51(3):1033-1040.