Cancer

I.What is cancer?

  1. Cancer is also called ‘Malignant Tumour’. It is the unlimited growth of abnormal cells, which can spread to different parts of the body. It can affect the normal function of different organs and may lead to death.
  2. According to the statistics from the Hong Kong Cancer Registry (HKCaR), the five most commonly diagnosed cancers in 2022, in sequence, were lung cancer, breast cancer, colorectal cancer, prostate cancer and liver cancer.
  3. Early detection and timely treatment of cancer increase the chance of cure. Also, a healthy lifestyle can reduce the risk of acquiring cancers.

II. Risk factors for cancer

Some risk factors of cancer are non-modifiable, including age, gender and family history of cancer; while many other risk factors are modifiable:

  1. Overweight and obesity: Being overweight or obese increase the risk for many types of cancer including liver cancer, prostate cancer, ovarian cancer, cancer of gallbladder, kidney cancer, colorectal cancer, oesophageal cancer, postmenopausal breast cancer, pancreatic cancer, corpus uteri cancer (also known as endometrial cancer) and stomach cancer.
  2. Lack of physical activity: Studies have shown that the lack of physical activity independently increases the risk of more than ten types of cancer, for example, liver, prostate, colorectal, breast and uterine cancers. It also increases the chance of being overweight and obese.
  3. Unhealthy diet: Inadequate consumption of dietary fibre, excessive consumption of red meat (especially processed meat), high intake of food with high fat and high sugar contents, mouldy food, drinking very hot beverages and preserved food like Chinese-style salted fish would increase the risk of different cancers.
  4. Smoking: Smoking increases the risk of a variety of cancer types, such as lung, oral cavity, pharynx, larynx, etc. Conventional cigarettes, electronic cigarettes and heated tobacco products would all generate a wide range of harmful substances including carcinogens.
  5. Alcohol consumption: Alcohol is classified by the International Agency for Research on Cancer under the World Health Organization (WHO) as a Group 1 Carcinogen. In terms of cancer risk, there is no safe level of drinking. Risk of cancer increases with the amount of alcohol consumed. The more alcohol consumed and cumulated over time, the higher the chance of suffering from a wide range of cancers such as oral cavity, pharynx, larynx, oesophagus, liver, colon and rectum; and female breasts.
  6. Excessive exposure to Ultraviolet (UV) radiation: It increases risk of skin cancers.
  7. Environmental pollution and occupational exposure to carcinogenic substances: Exhaust from factory and vehicles, prolonged occupational exposure to carcinogenic substances, such as asbestos and radiation, increase the risk of cancer.
  8. Chronic infection by some cancer-causing viruses: The majority of liver cancer cases are related to hepatitis B virus and hepatitis C virus infection in Hong Kong. Almost all cervical cancers are caused by persistent infection with one of the cancer-causing (or high-risk) types of human papillomavirus.

III. Tips for cancer prevention

  1. Maintain optimal body weight and waist circumference: For Chinese adults in Hong Kong, a Body Mass Index (BMI) between 18.5 and 22.9 is optimal. Besides, irrespective of their BMI, Chinese men and women in Hong Kong should keep their waist circumference below 90 cm and below 80 cm respectively to maintain optimal health.
  2. Be physically active: Choose appropriate physical activities, do it regularly and build a habit. According to the WHO recommendations, for all adults aged 18 or above and elderly who are healthy and without any contraindication to physical activity, should perform at least 150 minutes of moderate-intensity aerobic physical activity, 75 minutes of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate- and vigorous-intensity aerobic physical activity in a week.
  3. Have a healthy balanced diet: It shall include a variety of foods, adequate intake of fruits and vegetables, reduction of consumption of red meat, and avoidance of consumption of processed meat, preserved food, mouldy food and very hot beverages.
  4. Avoid smoking and second hand smoke.
  5. Avoid alcohol consumption.
  6. Protect against excessive UV exposure: When out in the sun, one should take the necessary protective measures (e.g. wear a wide-brimmed hat and long-sleeved clothing; and apply a broad-spectrum sunscreen lotion of at least SPF 15).
  7. Minimize environmental and occupational exposure to carcinogenic substances: Maintain good indoor ventilation and avoid inhalation of gaseous air pollutants from vehicles. Necessary protective measures should be adopted for workers who may expose to carcinogenic substances at work, e.g. asbestos dust and radiation.
  8. Practice safe sex: Some cancer-causing infections such as hepatitis B virus and human papillomaviruses can be transmitted through sexual contact. Use of condom and avoiding high risk sexual activity (such as having multiple sexual partners) can help to reduce the risk of getting cancer-causing infections contracted through sexual contact.
  9. Get vaccinated against hepatitis B virus and human papillomaviruses.
  10. People with chronic hepatitis B should have regular examination for early detection of changes in the liver condition, such as blood test for liver function, alpha-fetoprotein and viral load, and ultrasonographic abdominal examination. For any abnormality, one should follow doctor’s instruction to receive treatment and follow-up.

IV. Warning symptoms of cancer

In general, the symptoms of cancer may not be obvious or specific at early stage. The elderly should always be alert to any changes in their health conditions, especially recurring symptoms. Seek medical advice promptly if there is unexplained weight loss, loss of appetite, fatigue, or the following symptoms:

  1. Change in urinary or bowel habits, or blood in urine or stool
  2. Lumps (no matter painful or painless)
  3. Abnormal vaginal bleeding
  4. Blood in nasal secretion or sputum
  5. Prolonged coughing or hoarseness of voice
  6. Hearing loss or ringing in one ear
  7. Sores or ulcers that do not heal (e.g. affecting skin, tongue, oral cavity or lips)
  8. Indigestion or swallowing difficulties
  9. Abdominal discomfort or pain, including cramps; or bloating
  10. Obvious change of wart or mole (enlarged, spontaneous bleeding, or change in color)

V. Cancer Screening

Screening means examining people without symptoms in order to detect disease or identify people at increased risk of disease, thereby allowing timely treatment, so as to improve patient outcome and reduce mortality.
The Government has launched the Cervical Screening Programme and the Colorectal Cancer Screening Programme. For more information, please visit the designated thematic websites.

VI. Relevant information

1.Cancer Online Resource Hub https://www.cancer.gov.hk/en/index.html
2.Cervical Screening Programme, Department of Health https://www.cervicalscreening.gov.hk/en/index.html
3.Colorectal Cancer Screening Programme, Department of Health https://www.colonscreen.gov.hk/en/index.html
4.Hong Kong Cancer Registry, Hospital Authority https://www3.ha.org.hk/cancereg/
5.The Hong Kong Anti-Cancer Society https://www.hkacs.org.hk/en/
6.Hong Kong Cancer Fund https://www.cancer-fund.org/en/
7.Tobacco and Alcohol Control Office, Department of Health https://www.taco.gov.hk/main/english/index.html
8.The Integrated Smoking Cessation Hotline of the Department of Health 1833 183
9.Smoking Counselling and Cessation Hotline: “Quitline”, Hospital Authority 2300 7272
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