Cervical cancer screening
This week is cervical cancer screening week so I thought I would complete my week of social media posts with a more comprehensive blog talking about the cervical cancer screening programme.
Why is cervical cancer screening important?
Cervical cancer screening is important as it can help to prevent cervical cancer. Sadly, if cervical cancer is not detected until it has become invasive, about a third of women will die from the condition within 5 years.
Invasive cancer is a type of cancer that has spread beyond the layer of tissue where it initially developed and has invaded surrounding healthy tissues. Here’s a breakdown:
Spread: Unlike non-invasive (or in situ) cancers that remain in their original location, invasive cancers break through tissue barriers.
Aggressiveness: They can grow more quickly and spread to other parts of the body, making them more dangerous and harder to treat.
Metastasis: Invasive cancers can enter the bloodstream or lymphatic system, leading to the development of secondary tumors in other organs.
Thankfully, cervical cancer goes through several stages before it becomes invasive, and abnormalities can be detected even before cervical cancer occurs, called cervical intraepithelial neoplasia (CIN). CIN refers to the abnormal growth of cells on the surface of the cervix, which can potentially progress to cervical cancer if left untreated. The condition is categorized based on the extent of abnormal cell growth:
CIN 1 (Mild Dysplasia): This is the least severe form and involves the lower third of the cervical lining. Most cases of CIN 1 regress spontaneously without treatment, but regular monitoring is essential.
CIN 2 (Moderate Dysplasia): This involves about two-thirds of the cervical lining. It has a higher risk of progressing to severe dysplasia or cancer and may require treatment to remove the abnormal cells.
CIN 3 (Severe Dysplasia or Carcinoma in Situ): This is the most severe form, affecting more than two-thirds of the cervical lining and potentially the entire thickness. CIN 3 is considered a precancerous condition and typically requires treatment to prevent progression to invasive cervical cancer.
Instigating treatment early, when there are still pre-cancerous changes, prevents the development of cervical cancer. Cervical cancer screening detects these pre-cancerous changes and therefore is vital in the prevention of cervical cancer.
Does cervical cancer screening detect cervical cancer?
The screening programme is designed to detect the pre-cancerous CIN changes, rather than to detect cervical cancer. However, the test will also detect early stage cancers, which if treated promptly, significantly increases outcomes, with 95-98% of women surviving to 5 years.
Does cervical cancer screening detect any other cancers?
Sadly no. Smears can only detect cervical cancers and there are no good screening tests for other types of gynaecological cancers.
What is HPV?
Human papillomavirus (HPV) is a double-stranded DNA vrius that targets the skin and anogenital tracts. About 40 types can infect the genital area. While many HPV infections are symptom-free and resolve on their own, some can lead to genital warts and cancers in women. HPV types are classified as 'high-risk' or 'low-risk' based on their potential to cause cancer.
HPV is a leading cause of cervical cancer, with high-risk type found in 99% of cases. In Europe, PHV16 is linked to nearly 60% of cervical cancers, and HPV18 to over 15%. There are also 11 other high-risk types to be aware of.
Around 70% of new HPV infections clear within a year, and 90% clear within two years. However, persistent infection with a high-risk type, especially HPV16 or HPV18, significantly increases the risk of developing cervical pre-cancer and cancer. The time between infection and pre-cancerous lesions can range from 1 to 10 years, and even longer for invasive cancer.
How do you get HPV?
Genital HPV is mainly spread through secual contact, including intercourse. Your risk increases with:
1. More sexual partners
2. New partners
3. The sexual history of your partners
Studies show that nearly 40% of women contract at least one type of HPV within two years of becoming sexually active.
Effectiveness of Condoms in Preventing HPV
Partial Protection: Condoms provide significant but partial protection against HPV. They cover the penis and some of the genital area, reducing the likelihood of HPV transmission during sexual activity.
Reduction in HPV-Related Diseases: Regular condom use has been shown to reduce the incidence of HPV-related diseases, such as genital warts and cervical intraepithelial neoplasia (CIN), which are precursors to cervical cancer.
Studies and Evidence:
Research indicates that consistent condom use can reduce the risk of acquiring genital HPV infection by about 70% compared to non-use .
Condom use also lowers the risk of HPV transmission between partners and reduces the progression of HPV-related lesions.
Limitations of Condoms in Preventing HPV
Skin-to-Skin Contact: HPV is transmitted through skin-to-skin contact. Since condoms do not cover all genital skin, areas not covered by the condom can still be exposed to the virus.
Inconsistent Use: The protective effect of condoms is greatly diminished if they are not used consistently and correctly with every sexual encounter.
How high is the risk of cervical cancer
There are an average of nearly 4,000 new cases of invasive cervical cancer in the UK each year. The highest incidence is in women aged 30-34, with a smaller peak in their 80s. Over 50% of new cases occur in women over 40, and more than 15% in women over 65. For unvaccinated women, the lifetime risk of developing cervical cancer is 1 in 143. Luckily 99% of these cancers can be prevented by vaccinated and cervical screening.
At what age does cervical cancer screening start?
In the UK screening starts at the age of 25 and continues until the age of 64. The screening age used to be 20 but in 2013 this was increased. Lots of women worry about whether this puts younger women at risk of cervical cancer. However cervical cancer under the age of 25 is very rare. When screening was done on women between the age of 20-25 what they found was that there was a high incidence of HPV infection and low grade CIN changes, but that these were cleared naturally by the body and did not result in cervical cancer. Screening these women resulted in high numbers of further investigations and treatments, but did not impact on the number of cases of cervical cancer that were detected.
Treatment for cervical intraepithelial neoplasia (CIN), such as cone biopsy (also known as cervical conization) or loop electrosurgical excision procedure (LEEP), can have implications for future pregnancies. Here are the potential complications and considerations:
Increased Risk of Preterm Birth:
Cervical Insufficiency: Treatment procedures can weaken the cervix, leading to cervical insufficiency (also known as incompetent cervix). This condition may result in premature opening of the cervix during pregnancy, potentially causing preterm birth or miscarriage.
Risk Factors: The extent of cervical tissue removed and the number of procedures performed can increase the risk. For instance, multiple LEEP procedures or large cone biopsies may pose a higher risk.
Cervical Stenosis:
Narrowing of the Cervix: Scar tissue formation after treatment can lead to cervical stenosis, where the cervix becomes narrower than usual. This can sometimes affect fertility by making it harder for sperm to enter the uterus.
Increased Risk of Caesarean Section:
Cervical Changes: Depending on the extent of cervical tissue removed, there may be changes that make vaginal delivery more difficult or risky. This can increase the likelihood of needing a caesarean section (C-section) for delivery.
Miscarriage Risk:
Early Pregnancy Loss: While the overall risk is low, there is a slightly increased risk of miscarriage in pregnancies following treatment for CIN, especially if cervical insufficiency develops.
It was decided that the benefit of picking up a very small number of cases of cervical cancer was outweighed by the risks to future pregnancies.
When does cervical cancer screening stop?
Screening in the NHS stops at the age of 64. The only exception to this is if HPV is detected on the last screening test, in which case another screen is done a year later. This is done because on average women have fewer new partners and less sexual contacts as they get older, which reduces their risk of HPV vaccination. On a population basis this results in:
Low Incidence of Cervical Cancer: The risk of developing cervical cancer decreases with age, especially after menopause. Most cervical cancers are diagnosed in younger women, typically between the ages of 35 and 44.
Long Time Frame for Cancer Development: Cervical cancer usually develops slowly from precancerous changes (CIN) that can take years to progress to cancer. By age 65, most women who were at risk of developing cervical cancer would likely have already been detected through earlier screenings.
Why is cervical cancer screening performed every 3-5 years?
Cervical cancer screening is typically performed every 3 years for women aged 25-50 and every 5 years for women between 50-64. The interval between screening tests is determined by several reasons, related to the natural history of cervical cancer, the effectiveness of screening tests, and balancing benefits with potential harms:
Development of Cervical Cancer: Cervical cancer develops slowly from CIN, which can take several years to progress to invasive cancer. This slow progression allows for intervals between screenings.
Minimizing Harm from Overdiagnosis: Screening too frequently can lead to unnecessary follow-up procedures for abnormalities that would not progress to cancer. Longer intervals reduce the risk of overdiagnosis and unnecessary treatment while still detecting significant abnormalities.
Cost-Effectiveness: Screening at appropriate intervals balances the costs of healthcare resources and reduces unnecessary healthcare spending associated with excessive screening.
Patient Convenience and Compliance: Longer intervals between screenings improve patient compliance and convenience, reducing the burden of frequent medical appointments.
What is involved in having a cervical cancer screening test?
The NHS screening programme exclusively uses samples taken from the cervix by a ‘broom’. In order to collect a sample, a speculum is inserted into the vagina so that the cervix can be visualised.
The discharge and cells collected from the cervix are then transferred to a special pot, and sent away to the lab to be analysed.
When the laboratory receive the sample they will run HPV testing on the sample. Under the NHS cervical screening programme they use the Aptima HPV 16 18/45 genotype assay which allows for the detection of HPV types 16, 18 and 45. Together they are associated with over 75% of all squamous cell carcinomas and 94% of adenocarcinomas. Only if HPV is detected will the sample then be analysed to look for abnormal cells (called cytology).
Can you do a self-taken swab instead of having to have a speculum examination?
The NHS is currently running a trial in East London where they are posting out swab kits to women to take a vaginal swab themselves for HPV testing if they have not attended for a cervical smear. Therefore this is not something that is currently being offered nationally, but this may change if it is felt that it increasing uptake of the screening programme. Privately you can have a self-taken swab, and the accuracy of this test for the HPV virus is almost as accurate as having a sample taken from the cervix via a speculum. In about 1 in 5 cases, HPV will be found, and then a smear test would be recommended so that the cells can be examined, which is not possible currently from a self-taken swab. If you would like HPV testing after a change in partner or because you avoid having regular smears because you don’t want to be examined, then contact Sirona Health to discuss self-taken swabs.
What innovations are on the horizon for cervical cancer screening?
The WID-qCIN test is an innovative approach that assesses DNA methylation. findings suggest that the WID-qCIN/HPV16/18 combination is a more effective triage strategy for HPV-positive women, improving the detection of significant precancerous lesions and reducing the need for unnecessary colposcopy referrals. This innovative approach has the potential to enhance the efficiency and accuracy of cervical cancer screening programs.
Where can you book a cervical screening test?
Cervical screening is usually performed by your NHS GP, and is most commonly performed by a specially trained nurse at the practice. Alternatively you can have a smear test done privately which is also a service which we offer at Sirona Health.
What happens based on my test result?
There are three different outcomes and you will be informed which is the recommended course of action for you when you get your test results back.
Normal recall in 3-5 years
Repeat testing in 12 month
Referral to a gynaecologist for colposcopy (examination of the cervix under a special magnifying instrument).
Does the smear test detect STIs?
No, the NHS cervical screening programme does not include the testing for STIs. However, if you would like to be tested at the same time then you can request a STI swab from the person doing the test for you. The manufacturers of the Aptima Thin Prep have designed it so that STIs can be detected from the same sample and here at Sirona Health we can offer this combined test through our laboratory, which will allow for HPV testing, STI testing (Chlamydia trachomatis, Neisseria gonorrhoea, Myocoplasma genitalium, Ureaplasma species, Trichomonas vaginalis, Gardnerella vaginalis, Herpes Simplex I/II), and cytology if indicated.
Individualized Screening Recommendations
The NHS screening programme does not allow of individualisation however private healthcare allows for individualised recommendations based on risk factors, previous screening history and vaccination status (for HPV). Regular screening remains crucial for early detection and effective management of cervical cancer and precancerous lesions.
Some women continue to be at higher risk of HPV contraction later in life. Older women with any of the following risk factors may want to consider ongoing screening privately:
New Sexual Partners: Engaging in new sexual relationships later in life can expose individuals to new HPV infections, especially if their partners are HPV carriers.
Unprotected Sex: Not using condoms consistently and correctly can increase the risk of HPV transmission, regardless of age.
Weakened Immune System: Conditions or medications that weaken the immune system, such as HIV/AIDS, chemotherapy, or long-term steroid use, can make individuals more susceptible to HPV infection at any age.
Previous HPV Infection: While the immune system generally clears HPV infections, some individuals may have persistent infections or reactivation of latent infections, especially if their immune response weakens with age.
Smoking: Smoking has been linked to increased susceptibility to HPV infection and persistence of HPV-related lesions. Older adults who smoke may have a higher risk of HPV infection compared to non-smokers.
Lack of HPV Vaccination: Older adults who did not receive the HPV vaccine in their youth are susceptible to acquiring new HPV infections later in life.
Sexual Behavior History: A history of multiple sexual partners or high-risk sexual behaviors earlier in life can contribute to ongoing or recurrent HPV infections in older age.
Cervical cancer screening in pregnancy
Usually cervical screening is postponed if you are pregnant until 12 weeks after you have given birth. This is because changes to the cervix during pregnancy can make it more difficult to get an accurate result. It is therefore recommended that you have your routine screening done as part of your pre-conception care, if it is due. If however you are due a repeat test because you have had a previous abnormal result then the test can proceed without causing any risk to the pregnancy, and cervical screening does not cause miscarriage.
Cervical cancer screening and your periods
The test does not impact on your hormones or on the lining of your womb and therefore will not change you periods in anyway. Some women have a little bit of vaginal bleeding after the test but this will be light and of short duration.
Cervical screening during and after menopause
The reduction in oestrogen to the vaginal tissues which occurs from the perimenopause onwards can make having a speculum examination more uncomfortable in some women.
The use of vaginal oestrogen prior to a smear can make the world of difference to comfort levels if you know that you have had discomfort with smears in the past. Please ensure you’ve been on vaginal oestrogen for long enough; three months is ideal. Vaginal oestrogen is considered suitable and works just where it is needed, there is known to be very little absorption into the body’s system. In addition there is a new non-hormonal treatment for vaginal discomfort, ospemifene, for those of you who need to avoid hormones. You will need to have an appointment with either your NHS GP, or with us here at Sirona Health, at least three months prior to your smear test being due if you would like to discuss these options further.
Checklist before having your cervical smear
Can I have sex before my test? No, avoid intercourse for 48 hours before the exam.
Can I put things into the vagina before the test? No, don’t use vaginal medication, personal lubricants or douching 48 hours before the exam.
Can I have a test whilst I have my period? No, schedule your appointment 2 weeks after first day of the patient’s last menstrual period.