5 Myths About Cervical Cancer Screening
Too many women wrongly think they do not need to be screened for cervical cancer.
Earlier this year, Dr Chia Yin Nin, a gynaecological oncologist and surgeon, encountered an unusual situation: Within the space of a month, she diagnosed 10 patients with cervical cancer in her practice.
“Normally, we see one every three months,” she said.
According to Dr Chia, the women were aged between 29 and 73 and the majority of them were in their early 40s. “Most were married and in stable relationships. This is typically considered a low-risk group.”
The one common thread running through them: All but one had never been screened for cervical cancer.
Dr Chia believes that not enough women are getting screened for cervical cancer and as a result, a preventable cancer is claiming victims. She outlined five myths that are holding women back from getting screened.
1) I am healthy and have no symptoms. I do not need to go for cervical cancer screening.
Fact: The changes in the cervix that lead to cancer take place over decades with no symptoms. By the time symptoms appear, cervical cancer is already present.
Cervical cancer is caused by the human papillomavirus (HPV), which is sexually acquired. HPV is very common in the community. Once a woman is sexually active, one in two will become infected.
Most women will acquire the virus in their 20s but about 80 per cent of HPV infections are transient and the virus goes away. Unlike a cold, there are no signs or symptoms.
However, in 20 per cent of women, the virus stays in the cervix, causing a persistent infection. “These women will be at risk of cervical cancer in the long term,” said Dr Chia.
The infection initially leads to cell changes which usually occur many years before cancer develops. There are no signs or symptoms that these changes are occurring.
As a result, in most cases, women get infected in their 20s, pre-cancerous changes take place when they are in their 30s and cancer sets in when the women are in their 40s.
“We advise women to go for regular cervical screening. By the time symptoms – bleeding after intercourse, or in between menstruation – develop, it is too late.”
If the cancer is detected at Stage 1, the five-year survival rate is 90 per cent. At Stage 4, the survival rate is less than 10 per cent.
Pap smears are designed to pick up pre-cancerous changes in the cervix, known as CIN or cervical intraepithelia neoplasia. These are easily treated with laser or cone biopsy. “It is usually done in a day-surgery setting and the cure rate is in the region of 99 per cent,” she said.
Early treatment saves lives and also saves wombs. If caught early, there is no need to remove the uterus, she added.
2) I have had only one sexual partner, so I am not at risk of cervical cancer and I do not need to be screened.
Fact: HPV does not require penetrative sex to infect someone.
A woman may only have had penetrative sex with one person, but this will not protect her because HPV does not require penetrative intercourse. “You can acquire it from fondling or petting, as long as there is any contact with bodily fluids,” said Dr Chia. “It happens to all of us. It happens to average women from average families. You do not have to be a commercial sex worker to get this.”
“I am not asking you to doubt your partner; I am asking you to empower and protect yourself,” said Dr Chia.
3) My Pap smear came back negative so I do not have to worry about gynaecological cancers.
Fact: A Pap smear only picks up changes in the cervix. “It tells us nothing about the uterus, the ovaries or the fallopian tube,” she said. “If you have a negative Pap smear, it does not clear you of the other gynaecological cancers.”
Occasionally, a Pap smear does pick up cancers from other places such as the uterus or the ovaries but women should not rely on the Pap smear for this.
4) I am no longer sexually active so I do not need to be screened.
Fact: Even if you have only had one sexual contact 20 to 30 years ago, you are still at risk.
In cases such as these, women should have three consecutive negative screens (minimum three-yearly Pap smears or five-yearly HPV screens).
“After that, you are OK,” she said.
“We advise women that they do not need to screen after they reach the age of 79. However, the oldest woman to have cervical cancer was detected at age 81.”
5) I have been vaccinated, so I do not need to go for screening.
Fact: The best existing vaccine covers nine strains of the HPV high-risk subtypes. This accounts for 95 per cent of cervical cancers. However, this leave another 5 per cent of cervical cancers that are caused by different strains.
Whether a woman has been vaccinated or not, she should go for regular screening between the ages of 25 and 79 because vaccines do not cover all strains. There are more than 30 high-risk subtypes.
The other problem is that, in the past, vaccinations were given without testing the patient. However, vaccines are prophylactic, not therapeutic, so a woman who has a persistent HPV infection will not benefit from the vaccination.
“For a woman with persistent infection, the focus is on treating pre-cancer changes rather than preventing HPV infection,” said Dr Chia. It is possible to remove or reduce the virus load, so after that, they can get HPV vaccination once they are HPV negative again.
Pap smears: Not always fail-safe
Sometimes, even if someone does the vaccinations and the regular Pap smears, the system fails.
One of the 10 patients that Dr Chia had diagnosed with cervical cancer had been vaccinated and had also been doing regular Pap smears. She was a woman in her early 40s with three children and was in a stable relationship.
“When she saw me, she was in Stage 3 and her last Pap smear had been three months before. She was a very unfortunate patient; she had done all the right things,” she said.
The problem could have come from multiple sources, according to Dr Chia. In a Pap smear, the doctor or nurse will obtain sample cells from the cervix and the pathologist or cytotechnologists (the people who study sampled cells) will examine the slides. “There is a possibility of sampling errors if you do not sample the entire cervix properly or you can get interpretation errors.”
According to Dr Chia, there is a false negative rate of 30 to 40 per cent though this varies by region. “In Australia, the false negative rate is very low because pathologists or cytotechnologists have to go through mandatory certification, and they are audited. In a lot of developing countries, we cannot be 100 per cent certain of the quality.”
One solution is to do more frequent Pap smears to overcome the problem of false negatives. Alternatively, women can also request for a HPV test to see if they are infected with the high-risk HPV subtypes.
“HPV testing has been shown to have a much lower false negative rate than Pap smears. It is very sensitive and not prone to interpretation error. In many countries, the HPV test is replacing the Pap smear as the primary screen as it more accurate.”
Screening: Why and when
- Cervical cancer is the 10th most common cancer among women in Singapore, but is highly preventable and curable through regular screening.
- Screening is recommended for all women but targeted at those aged 25 and older who have engaged in sexual intercourse or are sexually active.
- Vaccinated or not, a woman should still go for regular screening.
- Screening can be done through a Pap smear, HPV test, or both.
Written by Jimmy Yap
|cancer screening, cervical cancer, human papillomavirus (HPV) cancer, misconceptions, pap smears, vaccination, women (gynaecological) cancer
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|PUBLISHED 08 MAY 2018