Cancer: Causes, Prevention, Treatment and Nutrition
Learning about cancer… virtually
A public webinar by Parkway Cancer Centre gives participants an overview of the causes, treatment and prevention of cancer.
Concerns over cancer do not diminish even in times of a global pandemic.
With safe distancing measures in place, Parkway Cancer Centre organised a public webinar on Understanding Cancer and Beyond on 9 May with more than 350 participants from countries such as Singapore, Bangladesh, India, Indonesia and the Philippines.
Dr Zee Ying Kiat, Senior Consultant in Medical Oncology, started the session with a discussion on understanding cancer and how it could be detected and treated.
The current Covid-19 pandemic adds an additional layer of fear in some people due to limited knowledge or misinformation about the coronavirus, much like how cancer can cause dread in some patients.
Dr Zee sought to allay some of these fears and anxieties by addressing commonly-asked questions about cancer.
Causes of cancer
Cancer arises when normal body cells start dividing in an uncontrolled manner. These mutated cells then attack surrounding cells and tissues and even spread throughout the body.
Dr Zee added that hereditary cancers are uncommon, and that most cancers develop as a result of changes during the course of one’s life. In fact, about one in five people will develop cancer, and one in 10 will die from cancer before they turn 75.
In Singapore, cancer is the leading cause of death, accounting for about three in 10 of all deaths, even more than heart and lung diseases. Every year, about 6,800 Singaporean men and 7,300 Singaporean women are diagnosed with cancer.
But can cancers be prevented? Dr Zee said many cancers are preventable with basic changes to our diet and lifestyle. Such lifestyle changes also protect a person against other chronic illnesses such as heart diseases, stroke and diabetes.
Some ways of preventing cancer include avoiding tobacco, limiting alcohol intake, eating a diet rich in fruits, vegetables, whole grains and low in saturated fat, being physically active and maintaining a healthy weight.
One of the best ways to prevent cancer, or at least detect it in the early stages, is screening. It helps to check for cancer (or for conditions that may lead to cancer) in people who do not display any symptoms yet.
Screening tests for cancer include physical examinations and history, laboratory tests like blood tests, and imaging procedures such as mammograms and CT scans.
Screenings, however, are not available for all cancers. For those cancers where screenings are possible, they are invaluable in aiding early detection. This, in turn, leads to much higher chances of survival, said Dr Zee.
For example, in breast cancer, the 10-year survival rate for patients with Stage 1 cancer is about 70 per cent. This drops to 2 per cent for Stage 4 patients.
“Early detection is vital because cancer survival decreases with advancing stage,” said Dr Zee.
In some cases, screening can help detect and remove abnormalities that, if untreated, could lead to cancer.
For example, if polyps are detected during a colonoscopy screening for colorectal cancer, the polyps can be removed, thereby preventing them from potentially turning cancerous in future.
Likewise, in cervical cancer, Pap smears aim to detect abnormal pre-cancerous cells known as cervical intra-epithelial neoplasia (CIN) and remove them before development of invasive cancer.
In terms of treatment, there is no single treatment for cancer. Rather, there is a range of options available depending on the cancer site and the stage of the illness. Different combinations of treatments may be used for greater effect.
Surgery is often used to remove tumours and surrounding tissue, and is the foundation of curative therapy. Advancements in technology allow less invasive treatments such as keyhole surgery or robotic surgery.
Surgery is often complemented by chemotherapy, either before or after surgery, and/or radiotherapy to maximise the chance of cure.
Chemotherapy refers to the use of drugs to kill cancer cells by interfering with their ability to divide, while radiotherapy uses high-energy X-rays or other types of radiation to destroy cancer cells.
Around 40 per cent of cancer patients usually receive radiotherapy at some point, either to treat their cancer or relieve symptoms.
Hormonal therapy uses drugs to adjust the levels of certain hormones which have been implicated in some types of cancer. For example, drugs such as Tamoxifen – a great success story for hormonal therapy – has been effective in blocking the effects of estrogen in breast tissue, and helps to prevent and/or treat some types of breast cancer.
In recent years, there have also been new methods of treatment such as targeted therapy and immunotherapy.
Targeted therapy interferes with specific molecules which cause cancers to grow and spread. This form of therapy has been shown to work in many adult cancers such as colorectal, lung, breast, stomach and liver cancers.
Immunotherapy is the use of a body’s natural immune system to fight cancer. It has been proven beneficial in cancers such as lung cancer, colon cancer, kidney cancer and melanoma skin cancer. It effectively “wakes up” the body’s immune system to cancer cells, which can inhibit the body’s immune response. By removing this inhibition, the body can fight the cancer using its own defences. Immunotherapy is increasingly being used to treat many cancers, especially Stage 4 cancers.
Dr Zee then took questions from the audience, who asked about a wide range of topics including the differences between a mammogram and ultrasound; whether radiation from imaging screenings can cause cancer, and threats from carcinogens.
Cancer and nutrition
After Dr Zee, Senior Dietitian Fahma Sunarja discussed some common questions surrounding nutrition and cancer.
With a strong link between obesity and certain types of cancer, maintaining a healthy weight, regular physical activity and reducing energy-dense foods all help in preventing cancer.
To maintain a healthy weight, there needs to be a balance between the food intake and what is being burned by the body.
Ms Fahma highlighted two eating strategies that some people have used to maintain a healthy weight.
Intermittent fasting – where a person eats for only eight hours a day and fasts for the rest of the 16 hours – works very well for some people as they consume fewer calories.
“It allows the body to rest and re-start,” said Ms Fahma. Intermittent fasting also helps with reversing insulin resistance and, when combined with physical activity, increases the body’s metabolic rate. However, she warned that those with existing conditions such as diabetes or metabolic syndrome should consult a doctor or dietitian before trying such a diet.
The Keto diet – which consists of 80 per cent fat and 15 per cent protein – forces the body to do something it does not naturally do, said Ms Fahma. It makes the body break down fat as its main energy source.
The Keto diet may cause health issues such as nutrient deficiency as it excludes a wide variety of vegetables, fruits and grains, she cautions. With so much fat to metabolise, it could make existing liver conditions worse, and the levels of protein in the Keto diet may also overload the kidneys. Such a diet may also cause constipation, mood swings and fuzzy thinking.
Instead, Ms Fahma recommended intuitive eating, where one creates a healthy relationship with food. “Everybody has their own needs and probably need to explore to find what works best for them,” she said.
Another way to keep healthy is regular physical activity. “Sitting is the new smoking,” said Ms Fahma. “Keep the body moving – focus on daily lifestyle activities like just walking to the supermarket rather than driving or taking a bus.”
One should aim for at least 150 minutes of physical activities in a week (or 30 minutes, 5 days per week).
Another good method is to reduce the intake of energy-dense food such as deep-fried foods or sweets.
It is all about making the right choices, said Ms Fahma. For example, just by eating lontong without gravy, one can reduce 300 calories and the amount of fat by a third. Eating steamed rice instead of fried rice means about 300 calories less as well.
Avoiding soft drinks high in sugar such as carbonated drinks and bubble tea can also help.
Watch your portion sizes and avoid buffets or free-flow food items as these tend to make you overeat.
“Big changes start with small steps,” said Ms Fahma. “But once you get started, it gets easier along the way.”
Written by Ben Tan
The article above is meant to provide general information and does not replace a doctor's consultation.
Please see your doctor for professional advice.