Understanding cancer
What increases your risk and what can you control? Dr Yeap Chee Loong has some answers
THE incidence of cancer in Malaysia is expected to double by 2040. Understanding cancer is important to tailor preventive efforts and reduce the cancer burden. Lifestyle and personal choices potentially influence our chances of developing cancer. This means that you have some control over your exposure to these factors.
Therefore, you have the power to minimise the effects of these elements and maximise your chances of keeping good health and living a happy life.
LIFESTYLE AND CANCER
Risk factors for cancer can be broadly divided into modifiable and non-modifiable factors.
Non-modifiable risk factors include genetic defects, gender and age.
Modifiable risk factors are related to lifestyle and the environment.
Lifestyle factors include smoking, diet (red meat and fried food), alcohol consumption, sun exposure, environmental pollutants, infection, stress, obesity and physical inactivity.
All these lifestyle factors have been proven to cause cancer.
For example, smoking was identified as early as 1964 as the primary cause of lung cancer.
Since 1910, chronic alcohol consumption has been revealed as a risk factor for oesophageal cancer, oral cavity cancers as well as liver, pancreas and breast cancer.
As much as 90-95 per cent of cancer cases have their roots in environment and lifestyle. This means only 5-10 per cent of all cancer cases can be attributed to genetic defects.
DIET AND CANCER
In 1981, it was estimated that approximately 30-35 per cent of cancer deaths were linked to diet.
How diet contributes to cancer is not fully understood. Chemicals that cause cancer are termed as carcinogens.
Most carcinogens that are ingested, such as nitrates, nitrosamines, pesticides and dioxins, come from food, or food additives, or from cooking.
Heavy consumption of red meat is a risk factor for several cancers, especially for colorectal, prostate, bladder, breast, stomach, pancreatic and oral cancers.
Charcoal cooking and/or smoke curing of meat also produces harmful carbon compounds which have a strong cancerous effect.
Long-term exposure to food additives such as nitrite preservatives and azo dyes has also been associated with the induction of carcinogenesis.
Furthermore, bisphenol from plastic food containers can migrate into food and may increase the risk of breast and prostate cancers while ingestion of arsenic may increase the risk of bladder, kidney, liver, and lung cancers.
Saturated fatty acids, trans fatty acids, and refined sugars and flour present in most foods have also been associated with various cancers.
STRESS AND CANCER
There is no clear answer to the link between stress and cancer. However, there are some proven theories that chronic stress weakens the immune system that plays a crucial role in controlling and eliminating cancer cells.
Continuous activation of the stress response and exposure to the associated hormones could also promote the growth and spread of tumours.
So based on these theories, we can at least believe that stress is not good for health.
Does a weak immune system cause cancer? Definitely! The immune system has the task to control and eliminate cancer cells.
Once cancer cells are “stronger” than the immune system, they will “defeat” the immune system, and continue to grow out of control.
OBESITY AND CANCER
The link between obesity and cancer is clear. Research shows that excess body fat increases our risk for several cancers, such as colon, breast (in postmenopausal women), endometrium, kidneys (renal cell), oesophagus (adenocarcinoma), gastric cardia, pancreas, prostate, gallbladder, and liver.
It also has been known that obesity has been associated with increased mortality from these cancers.
Studies also show that obesity will cause a greater number of cancers than smoking in the very near future.
Increased modernisation and a Westernised diet and lifestyle have also been associated with an increased prevalence of overweight people in many developing countries, including Malaysia.
In fact, 44 per cent of Malaysian are overweight and obese.