Cervical Cancer Screening And Vaccination: Understanding The Latest ...

WHAT CAN I DO IN MY PRACTICE?

Cervical cancer is preventable, and prevention is achieved not just through screening but also through vaccination. As mentioned, the uptake of cervical cancer screening in Singapore has continuously been suboptimal despite various initiatives introduced by the government. One of the main barriers to screening is lack of understanding of the importance of regular cervical cancer screening. A local study cited the top reasons why Singaporean women had never gone for cervical screening: 39.4% felt that they were healthy and it was unnecessary, while 13.6% had never heard of a Pap smear test.(6) Much remains to be done to correct these misconceptions and raise awareness about screening. Additionally, the uptake of HPV vaccination is low; a study done in a Singaporean tertiary institution in 2016 showed that only 9.8% of the female students had received the HPV vaccine.(11)

Family physicians play a pivotal role in increasing the uptake of these programmes, as they are at the heart of the community and have considerable power to influence the community’s health. Preventive health is an essential part of a family physician’s job scope. In order to be effective advocates for prevention of cervical cancer, all family physicians should continuously enhance their knowledge about important aspects of cervical cancer screening and prevention, such as the role of HPV in screening and HPV vaccines. Various societies in Singapore offer continued medical education in this aspect, including the Singapore Cancer Society, Society for Colposcopy and Cervical Pathology of Singapore, and the Health Promotion Board.

HPV vaccines as primary prevention against cervical cancer

HPV vaccines are prophylactic viral-like particles designed to enhance host immunity against certain high-risk HPVs while lacking the ability to infect the host. The safety profile of HPV vaccines is well documented.(12) Currently, there are three types of HPV vaccines (bivalent, quadrivalent and nanovalent) in Singapore. All these vaccines are equally effective in protecting against the most common high-risk HPV types (Type 16 and 18). The main difference among them is the additional coverage provided (Table I).

Table I

HPV vaccines available in Singapore.

As exposure to HPV can occur during sexual intercourse,(2) it is recommended that the vaccine be given to adolescents prior to their first sexual contact. Family physicians should target these population groups when advocating for vaccination. In Singapore, HPV vaccination is licensed to be given to both men and women between the age of nine and 26 years for both the bivalent and the quadrivalent vaccines. In September 2020, the nanovalent vaccine was approved to be given to men and women up to the age of 45 years, following emerging evidence of continued protective benefits for these groups.(13,14)

In May 2019, the Ministry of Health (MOH) launched the national school HPV vaccination programme, which offers the bivalent HPV vaccine to all female Secondary 1 students. The bivalent and quadrivalent HPV vaccines are also available under Medisave coverage to all women in Singapore between the ages of nine and 26 years.

Cervical screening as secondary prevention against cervical cancer

At the same time, the MOH also launched the updated national cervical cancer screening guidelines (Cervical Screen Singapore) incorporating HPV primary screening for women aged 30 years and above.(15) Table II summarises the changes in screening guidelines. Note that regardless of HPV vaccination status, all women who fulfil these criteria should be screened.

Table II

Old vs. new cervical cancer screening guidelines in Singapore.

These changes in the national cervical screening guidelines were made as a response to the plethora of emerging evidence over the years regarding the superiority of HPV DNA tests compared to cytology in detecting pre-invasive cervical disease. Other benefits include the increased screening interval, providing better cost-effectiveness compared to conventional cytology screening.(16)

The guideline recommends conventional cytology screening for women aged 25–29 years rather than HPV screening. This is because a positive HPV test in this age group is not a true reflection of a woman’s risk of cervical cancer in the future. In this age group, and particularly in Singapore, where uptake of HPV vaccination is low, there is a high incidence of transient HPV infection.(3) Most women would eventually be clear of the HPV infection, without increased risk of cervical cancer in the future. Additionally, there are concerns that high rates of HPV positivity in this age group would result in an increased number of unnecessary colposcopies and invasive interventions such as cervical biopsy and colposcopy treatment. These, in turn, expose women to unnecessary physical and psychological morbidities later. Unnecessary colposcopy treatment has been shown to lead to significant future reproductive and pregnancy-related morbidities as well.(17)

Lastly, if patients have symptoms such as abnormal per vaginal bleeding or suspicious cervical lesions on speculum examination, a cervical smear is inappropriate. Such patients should be referred for further evaluation by a gynaecologist. The aim of cervical cancer screening is to detect women at high risk of pre-invasive cervical disease, and it should be done on asymptomatic women with a normal-looking cervix during speculum examination. Pre-cancer cells and HPV infection do not present with any symptoms and are invisible to the naked eye; screening is the only way to detect their presence.