Primary Prevention

 

Primary prevention is an important strategy in lowering the risk of developing cervical Some preventive measures can help reduce the HPV infection and the progression from persistent HPV infection to cervicalcancer:

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1. Practise safer sex (such as avoid having multiple sexual partners and use condoms) to reduce the chance of HPV infection and to protect against sexually transmitted diseases

2. Do not smoke

3. Get HPV vaccination before initiation of sexual activity

 

Apart from the measures highlighted above, cervical cancer screening offers women additional protection.

 

HPV vaccines cannot offer a 100% full protection from cervical cancer. HPV vaccination does not replace the cervical cancer screening. For details, please refer to the document “Consensus Statement on the use of Human Papillomavirus (HPV) in prevention of cervical cancer” at CHP website:www.chp.gov.hk/en/sas1/101/110/102.html.

 

 

Early detection

 

Early stage of cervical cancer and pre-cancerous cell changes may produce no symptoms at all. Common signs and symptoms of cervical cancer include abnormal vaginal bleeding (for example, between periods, during or after sex, and after menopause), vaginal discharge with foul smell, and discomfort or pain during sex. Individuals with these signs  and symptoms should seek medical assessment and investigation.

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Secondary prevention means screening, i.e. examining people without symptoms in order to detect disease  or  identify people  at  increased  risk of disease. Since CRC arises predominantly from precancerous adenomatous polyps developed over a long latent period, it is one of the few cancers that can be effectively prevented through organized and evidence-based screening. In general, subjects to consideration for colorectal cancer screening, people can be classified into “average risk” and “increased risk” groups.

 

According to screening recommendations made by the CEWG, people with “increased risk” refer to individuals who have a significant family history, such as those with an immediate relative diagnosed with colorectal cancer at the age of 60 or below; or those who have more than one immediate relatives diagnosed with colorectal cancer irrespective of age at diagnosis; or those who have immediate relatives diagnosed with hereditary bowel diseases. People with “average risk” refer to individuals aged 50 to 75 who do not have the aforesaid family history.

 

Screening

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Screening can prevent cervical cancer by detecting and treating pre-cancerous abnormalities of the cervix. Health Organization recommends cervical HPV testing and visual inspection with acetic acid (VIA) as the screening tests for cervical cancer. Decision on the screening approach should be based on the cost-effectiveness and infrastructure of the local context.

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Cervical Cytology

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Currently, cervical cytology is a primary screening strategy for reducing cervical cancer mortality in Hong Kong. There are two methods to conduct cervical cytology – conventional cervical smear (also known as Pap smear) or liquid-based cytology (LBC) and both of them are acceptable.

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According to a collaborative study of screening programmes in eight countries performed by the International Agency for Research on Cancer, the percentage reduction in cumulative incidence in women aged 35-64, who have been screened before age 35, is 93.5% when the interval between cervical smear is 1 year, 92.5% at 2 years, 90.8% at 3 years, 83.6% at 5 years and 64.1% at 10 years, assuming 100% compliance. Screening every one to two years provides little additional protection compared with screening every three years.

 

Recent systematic review conducted by the U.S. Preventive Services Task Force also supported the use of conventional cytology or LBC for cervical cancer screening and both of them can reduce cervical successfully. 

 

HIV Testing

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Worldwide, HPV16 and HPV18 are the most frequent high-risk HPV genotypes, amounting to an estimated 53.5% and 17.2% of all cervical cancers respectively. HPVtesting for high-risk HPV types has been introduced as an alternative screening tool. HPV testing generally has higher sensitivity and can be done at longer intervals than cytology alone. However, HPV testing has lower specificity than cervical cytology in detecting cervical intraepithelial neoplasia II (CIN2) and CIN3. False-positive rates are higher among women younger than age 30 because of higher prevalence of transient HPV infection.

 

The value of HPV testing can be three-fold:

1. as a triage of Atypical Squamous Cells of Undetermined Significance (ASCUS) cases for colposcopy ;

2. as primary screening either as a co-test with cytology or as a stand-alone test ;

3. as test of cure following treatment of CIN

 

Although HPV testing has been increasingly applied in primary screening either as a co-test with cytology or as a stand-alone test in some countries such as the United States and Australia , the efficacy and cost-effectiveness vary in different clinical and social-economical settings. Therefore, while more local data and cost-benefit analysis are needed to assess the applicability of HPV testing in Hong Kong, cervical cytology remains the most effective screening tool for population-based cervical cancer screening in Hong Kong.