Can we prevent cancer?
Updated: Aug 29
Yes and no.
Because each person is exposed to unique environmental and lifestyle factors, cancer risk can vary. Although some factors cannot be controlled (such as inherited genetic mutations), there is a range of modifiable environmental and lifestyle factors that can help reduce the risk of developing cancer.
According to the World Health Organization (WHO), a 30-40% cancer burden can be attributed to lifestyle risk factors such as tobacco smoking, alcohol consumption, a diet low in fruit and vegetables, overweight and obesity, and physical inactivity. In a 2018 report by the World Cancer Research Fund (WCRF) and the American Institute of Cancer Research (AICR), not-for-profit organizations that lead a network of cancer prevention charities with a global reach, 10 cancer prevention recommendations on diet and nutrition were developed. Taken together, they promote a lifestyle consisting of a healthy dietary pattern, physical activity, and weight management. This may not only help reduce the risk of cancer but may also contribute to the prevention of obesity and other chronic diseases such as type 2 diabetes and cardiovascular disease.
Here is a closer look at some of their recommendations:
Maintain a healthy weight
To determine one's healthy weight range, we can look at body mass index (BMI), waist circumference, and waist-to-hip ratio.
BMI measures one’s weight in relation to height. It is calculated by using a person's height and weight. The formula is BMI = kg/m2 where kg is a person's weight in kilograms and m2 is their height in metres squared.
The World Health Organization (WHO) defines overweight as a BMI of ≥ 25 and a BMI of ≥ 30 for obesity. However, because at any given BMI, Asians, including Singaporeans, generally have a higher percentage of body fat and less muscle mass than do Caucasians, the BMI cut- off levels for Singaporeans have been revised as seen on the table below.
Each increase of 5 points in BMI was associated with a 50% higher risk of endometrial cancer, 48% higher risk of esophageal adenocarcinoma, 30% higher risk of kidney cancer, 30% higher risk of liver cancer, 12% higher risk for postmenopausal breast cancer, 10% higher risk of pancreatic cancer, and 5% higher risk of colorectal cancer.
Waist circumference is a good measure of fat around your middle. This type of fat builds up around your organs, and is linked to high blood fat levels, high blood pressure and diabetes. A larger waist usually also means there is excess fat inside your organs. Each 4-inch increase in waist circumference was shown to increase the risk of esophageal adenocarcinoma by 34%, pancreatic cancer by 11%, postmenopausal breast cancer by 11%, kidney cancer by 11%, endometrial cancer by 5%, and colorectal cancer by 2%.
A waist-to-hip ratio (WHR) measures one’s waist size divided by hip size. People who carry more weight in the belly (apple shape) are at higher risk for cancer and other chronic diseases than those who carry more weight in the hips (pear shape). The WHO recommends a healthy WHR to be 0.9 or less in men and 0.85 or less in women. Each 0.1 unit increase in waist-hip ratio significantly increased the risk of esophageal adenocarcinoma by 38%, kidney cancer by 26%, endometrial cancer by 21%, pancreatic cancer by 19%, postmenopausal breast cancer by 10%, and colorectal cancer by 2%.
Be physically active Physical activity is defined as any movement that uses skeletal muscles and requires more energy than does resting. Physical activity can include working, exercising, performing household chores, and leisure-time activities such as walking, jogging, running, yoga, hiking, bicycling, and swimming.
There is evidence from various studies that show that the most physically active individuals had lower risk of breast, endometrial, colon, and lung cancers. Furthermore, the protective effect was stronger for postmenopausal women.
Eat a healthful diet An overall healthy dietary pattern has the potential to lower cancer risk by 10-20%. This can be achieved via the the following dietary recommendations:
Limit alcohol consumption. There is strong evidence that consumption of alcoholic drinks is a cause of cancers of the mouth, pharynx and larynx, esophagus (squamous cell carcinoma), liver, colorectum, and breast (particularly postmenopause). Every 10 grams of alcohol (as ethanol) consumed per day elevated the risks of these cancers by 4-25%.
Eat a diet rich in whole grains, vegetables, fruit, and beans. There is strong evidence that eating whole grains protects against colorectal cancer, and that eating foods containing dietary fiber protects against colorectal cancer, weight gain, overweight, and obesity, which, as described above, increases the risk of many cancers.
Limit “fast” foods. Fast foods are readily available convenience foods (such as burgers, fries, nuggets) that tend to be energy-dense and are often consumed in large portions. There is strong evidence that diets containing higher amounts of fast foods and other processed foods causes weight gain, overweight, and obesity, which are a risk factor for many cancers.
Limit red and processed meat. Red meat includes all types of muscle meat from a mammal, including beef, veal, pork, lamb, mutton, horse, and goat. Processed meat has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavor or improve preservation. The risk of colorectal cancer increased by 16% with every 50g/day of processed meat intake, and by 12% with every 100g/day of red meat intake. Because meat can be a valuable source of nutrients, in particular protein, iron, zinc, and vitamin B12, the recommendation is to limit rather than completely avoid minimally processed red meat.
Limit sugar-sweetened drink which is a cause of weight gain, overweight, and obesity in both children and adults, especially when consumed frequently or in large portions. As noted above, obesity increases the risk of many cancers.
Avoiding tobacco and excess sun exposure The recommendations also emphasize that not smoking and avoiding other exposure to tobacco and excess sun are also important in reducing cancer risk.
And last but not least, participate in screening which allows early detection and treatment. With early detection and treatment, there is higher cancer survivorship rate, lower cancer recurrence risk and lower need for more extensive treatment.