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HPV screening helps prevent cervical cancer

HPV vaccination has been included in the National Childhood Immunisation Programme here since 2010.
HPV vaccination has been included in the National Childhood Immunisation Programme here since 2010.PHOTO: ISTOCKPHOTO

Women aged 25 to 69 should go for testing; virus can be transmitted through petting too

Most sexually active men and women are infected with the human papillomavirus, or HPV, at some point in their lives.

This is because transmissions are through sexual activity such as intercourse or even petting.

Many, however, are unaware of it or the health problems it can cause.

Although most HPV infections are cleared by the body naturally, persistent infections can cause health problems such as genital warts and cancer.

Almost all cervical cancer cases are caused by HPV infections, albeit often over a long period of more than 10 years.

Although most HPV infections are cleared by the body naturally, persistent infections can cause health problems such as genital warts and cancer.

Results of a Roche Diagnostics survey released recently showed that only 9 per cent of Singapore women surveyed think they are at high risk of developing cervical cancer and two in five women here have never undergone a Pap test - also known as a pap smear - to screen for that cancer.

Dr Chia Yin Nin, president of the Society for Colposcopy and Cervical Pathology of Singapore, said at an event in May that it is a shame that cervical cancer - which can be prevented - is so common. It is the 10th most common female cancer in Singapore.

She said most people do not understand how high their risk of cervical cancer can be. "If you have been in a monogamous relationship, you could still be at risk.

"The virus doesn't have to be transmitted only through penetration. It could be through petting and fondling."

  • Misconceptions about HPV

  • There are vaccines that can prevent the cancer caused by certain human papillomavirus (HPV)types.

    Professor Tay Sun Kuie, a senior consultant in the Department of Obstetrics & Gynaecology at the Singapore General Hospital, sheds light on some misconceptions about HPV:

    Myth: HPVis linked only to cervical cancer

    Certain strains of HPV cause cancer of the uterine cervix, vagina and vulva (external genital part) in women; cancer of the penis in men; cancer of the anus and the head and neck region in men and women.

    Some of these cancers are commonly seen in Singapore. For example, two new cases of cervical cancer are diagnosed every three days.

    Myth: HPV vaccines are not safe

    Two vaccines – Gardasil and Cervarix – prevent infection of HPV types 16 and 18, which cause 70 per cent or more of these cancers.

    Both have been approved by the the Health Sciences Authority (HSA) for routine use.

    International clinical studies and reports from countries with high vaccination uptake rates among young adolescents have confirmed that HPV vaccination is highly effective in preventing the precursor stage of cervical cancer.

    Globally, more than 300 million doses of HPV vaccines have been delivered over the past 10 years.

    The World Health Organisation has also issued statements to confirm the good safety record of HPV vaccines.

    Myth: HPV vaccines are not for young children

    HPV vaccination has been included in the National Childhood Immunisation Programme here since 2010.

    Young children are targeted for the vaccination as they show a much better immune response than older children. The programme recommends HPV vaccination for women between the ages of nine and 26.

    The standard regimen of HPV vaccination is given by injection into the shoulder muscle in three separate doses over six months.

    However, those below 14 years old can now be given a two-dose regimen over six months.

    Myth: HPV vaccination is only for girls

    In 2011, the HSA approved Gardasil for the vaccination of boys and men, aged from nine to 26 years old, based on its effectiveness and safety data.

    In fact, the immune response to HPV vaccination is better among boys, compared with girls of the same age.

    Vaccination for males is available at private clinics and is not included in the National Childhood Immunisation Programme.

    Joyce Teo

Women aged 25 to 69 should go for cervical cancer screening. At 69, they can stop if they have had three negative results, she said.

Regular screening helps to detect problems that can be treated before they turn serious.

"When you get infected with the HPV virus, there are no signs, no symptoms," said Dr Chia, who is also a gynaecological oncologist at Gleneagles Hospital.

A pap smear would not pick it up until it has caused abnormal changes in the cells. But a HPV test can.

Although there are no guidelines on HPV testing here yet, Dr Chia recommends doing the test every five years as it can identify 14 high-risk HPV types and can check for types 16 and 18, which cause 70 per cent of all cervical cancers.

"A negative (normal) HPV test is much more accurate than a negative pap smear," she said.

Dr Thomas Wright, an expert in gynaecological pathology who spoke at a recent conference on gynaecological diseases, said that a pap smear alone is not enough to screen for cervical cancer, and that a HPV test should be done as a primary test, or along with the pap smear.

Both pap smears and HPV tests involve taking samples of cervical cells for tests.

HPV TEST

This test checks for high-risk types of HPV that can cause cervical cancer over time.

"Women who test positive for HPV 16 and 18 are 35 times more likely to have pre-cervical cancer than those who are HPV negative," said Dr Chia.

One in four with HPV type 16 will develop pre-cancer while one in nine with HPV type 18 will develop pre-cancer, she said.

"The HPV test is like looking into a crystal ball to see if you will get cervical cancer," she added .

If a woman's HPV test is negative, which means that high-risk HPV types were not found, she has a very low risk of developing cancer.

"If you are tested negative, we don't have to see you for five years. If you are tested positive, we will have to recall you every six months to monitor you," said Dr Chia.

HPV testing is usually recommended for women aged 30 and above as HPV infection is very common in younger women and almost always transient.

PAP SMEAR

This checks for abnormal cells before they become cancerous. If these pre-cancerous cells are detected and treated early, the cancer can be prevented.

"A pap smear is not meant to pick up HPV infections," said Dr Chia.

In Singapore, women aged 25 to 69 who have had sexual intercourse are advised to take a pap smear once every three years. Pap smears have helped to reduce the rate of cervical cancers around the world but studies have shown that they are not as accurate as HPV tests.

"HPV testing is so much more sensitive than pap tests," said Dr Wright, Professor Emeritus of Pathology and Cell Biology at Columbia University in New York.

"An HPV test is a molecular test. You put it in a machine and you get the same result all the time. It rarely misses those with cervical disease."

This is unlike pap tests,where errors can easily occur in the interpretation of the results. "You're looking at an image of cells through a microscope and, sometimes, it is clear and, at other times, it is unclear," he said.

A version of this article appeared in the print edition of The Straits Times on August 23, 2016, with the headline 'HPV screening helps prevent cervical cancer'. Print Edition | Subscribe