Cancer Screening
Q1. What is cancer screening?
Cancer screening is testing healthy individuals to identify those having cancer before any symptoms appear. Cancer is the top killer in Hong Kong. Appropriate cancer screening tests allow early detection and early treatment, improve survival time and cure rate. Cancer screening only applies to individuals with no symptoms. If you suspect any early signs of cancer, please seek prompt medical attention for diagnosis of the underlying causes.
Q2. How to choose cancer screening?
What types of cancer screening should I receive? Not all cancers have suitable screening tests. Besides, screening tests have limitations, including false positives or false negatives. A positive test result does not necessarily mean you have cancer. It may lead to further tests that could be invasive and carry certain risks, which could trigger a chain reaction of worry. On the other hand, a negative test result does not completely rule out the possibility of cancer. It is therefore crucial to understand the nature and limitations of the screening tests before you take them.
You should consult your family doctor for appropriate cancer screening plan. Your family doctor can recommend the most suitable screening tests based on a thorough knowledge of your family history, overall health conditions and other risk factors of cancer. After screening, he/she will also explain the results to you in detail, follow up and in case of any abnormality, and make referral to a specialist for further diagnosis and intervention.
Q3. What are tumour markers?
Tumour markers, such as CEA, AFP, CA125, are substances produced by cancer cells or by the body in response to the presence of tumours. While the levels of these markers may be higher than normal in certain types of cancer patients, it does not necessarily indicate the presence of cancer if your marker levels happen to be high. Some non-cancerous conditions such as smoking and inflammation can also cause elevated tumor markers level. On the other hand, a normal level does not rule out the presence of cancer. You are advised to consult your family doctor for interpretation of test results.
Q4. What are the common types of cancer screening?
Here are some common types of cancer screening:
Cervical cancer screening: Over 90% of cervical cancer cases are caused by human papillomavirus (HPV), which is mostly transmitted through sexual intercourse. Therefore, regular cytology tests (Pap smear) and high risk HPV tests are recommended for women with sexual experience from age 25.
Colorectal cancer screening: Faecal Occult Blood Test (FOBT) and colonoscopy are common tests for screening of colorectal cancer. Individuals above 50 years old may consider an annual FOBT and a colonoscopy every 10 years. However, in case of risk factors such as family history of colorectal cancer, smoking, habitual consumption of processed meat, etc., colonoscopy is recommended. Colonoscopy allows doctors to obtain a clear view of the internal lining of the colon, and enable tissue biopsy and removal of polyps. As some polyps may be precancerous, early detection and removal may help prevent them from becoming cancer.
Breast cancer screening: The risk of developing breast cancer increases with age. Women aged above 44 should receive mammograms (X-ray examination of the breast) every two years. Those with high risk factors, such as BRCA gene mutation, a family history of breast cancer or ovarian cancer, should consult their doctors for appropriate screening options.
Lung cancer screening: Chronic smokers aged between 50 and 80, or those who have quitted smoking for no more than 15 years, should undergo lung cancer screening on an annual basis. The test is carried out with a low-dose CT (LDCT) scan, which provides more accurate and detailed images of the lung structures than conventional X-ray examinations.
Liver cancer screening: Individuals with high risk factors such as chronic hepatitis B, hepatitis C or cirrhosis are advised to undergo a liver ultrasound and blood tests (AFP) every six months.
Q5. What are some other ways to prevent cancer?
In addition to cancer screening, lifestyle modifications can help reduce the risk of cancer. Avoid smoking and drinking alcohol, maintain a healthy diet, eat more fruits and vegetables, reduce consumption of red meat and processed foods, engage in regular exercise and receive HPV vaccination. All these measures can contribute to cancer prevention.
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