Brief overview
- What is cervical intraepithelial neoplasia (CIN)? Cell change on the cervix, precursor of cervical cancer.
- Course: Can regress again. CIN I and II can be waited for, CIN III is usually operated on immediately (conization).
- Symptoms: CIN does not cause any symptoms
- Causes: Chronic infection with human papillomaviruses, especially high-risk virus types HPV 16 and 18.
- Risk factors: Frequently changing sexual partners, concurrent infection with herpes viruses or chlamydia, smoking, immunodeficiency
- Diagnostics: PAP smear, vaginal endoscopy, taking a tissue sample (biopsy), HPV test
- Treatment: Regular check-ups, anti-inflammatory drugs if necessary, surgery (conization)
- Prevention: HPV vaccination, regular check-ups with gynecologist
What is cervical intraepithelial neoplasia (CIN)?
CIN is the abbreviation for “cervical intraepithelial neoplasia”. This is the medical term for superficial cell changes on the cervix which, if left untreated, may develop into cervical cancer.
The cause of the cell changes is chronic infection with human papillomaviruses (HPV). HP viruses are very widespread; almost every woman becomes infected with them in the course of her life. Transmission occurs through sexual intercourse.
A diagnosis of CIN does not automatically mean that you will develop cancer. Some CINs regress on their own. Whether and how CIN are treated depends on the extent of the cell changes (dysplasia).
Differentiation between CIN 1, 2 and 3
Doctors divide cervical intraepithelial neoplasia into three grades of severity:
- CIN I (CIN 1): low-grade dysplasia
CIN I involves mild cell changes that heal on their own in a good half of women.
- CIN II (CIN 2): moderate-grade dysplasia
CIN II describes a moderately severe form of cell change. It resolves itself in one third of affected women.
- CIN III (CIN 3): high-grade dysplasia (invasive squamous cell carcinoma)
In CIN III, the cell changes are already far advanced. The changes are still limited to the upper tissue layers (carcinoma in situ, CIS), but could progress to carcinoma. Since CIN IIl only regresses on its own in very few women, doctors usually advise immediate surgery for this finding.
Can a CIN regress?
CIN I heals spontaneously and without treatment in 60 percent of cases. In 30 percent of cases, the cell changes remain. In this case, the doctor checks the cervix once a year during the gynecological checkup. 10 percent of all CIN I cases develop over many years into CIN III. If CIN I is present, the doctor checks every three months to see whether the cell changes are receding. If CIN I persists for more than two years, doctors recommend surgery (conization).
In the case of CIN II, 40 percent heal on their own within two years, another 40 percent persist, and in 20 percent of cases it develops into CIN III. CIN II does not have to be treated immediately. However, the doctor will perform a PAP test (microscopic examination of a cervical smear) and a vaginal endoscopy every three months to check how CIN II is developing. If the cell changes have not disappeared after one year, doctors usually advise surgery (conization).
If the doctor diagnoses CIN III, the chances of the cell changes regressing are only 33 percent. With this finding, it is very likely that the dysplasia will turn into cervical cancer. That is why doctors recommend surgery immediately at this stage.
How can you recognize a CIN?
Diseases of the genital tract often do not cause any clear symptoms. Pain or itching in the vaginal area or bleeding (outside of menstruation) should therefore always be taken seriously. If you notice anything unusual, contact your gynecologist. He or she will clarify the cause and decide whether and which treatment is appropriate.
What causes cervical intraepithelial neoplasia?
A CIN develops from an infection with human papillomavirus (HPV). It is the most common HPV-borne disease in the world. Genital HP viruses are transmitted during sexual intercourse and invade the mucous membranes.
Most women become infected with HP viruses during their lifetime, but only a few develop CIN as a result. In 80 percent of cases, the infection heals on its own and without symptoms within one to two years.
If the immune system fails to fight off the infection, the cells on the cervix can be so damaged by the HPV infection that precancerous lesions develop. However, it takes about five to ten years before cancer actually develops from a persistent HPV infection.
Risk factors High-risk HP virus type
Other risk factors for genital HPV infections
In addition to infection with high-risk HPV 16 and 18 types, other factors increase the risk for CIN:
- Frequently changing sexual partners: HP viruses are transmitted primarily during sexual intercourse. The risk of HPV infection increases with the number of sexual contacts. Condoms provide only limited protection because they do not cover all areas of the skin through which the viruses are transmitted.
- Smoking: Smoking not only promotes the development of cancer, but also infection with HPV. Nicotine accumulates in the mucous membrane of the cervix, weakening its defense function.
- Birth at a young age: For mothers, the risk of infection depends on the age at birth of the first child and the number of children. This is because pregnancy changes the mucous membrane of the cervix, making it more susceptible to infection. So a woman who became a mother at 20 has a higher risk than a mother who had her first child at 35.
- Immunodeficiency: Immunocompromised people – such as HIV patients or the chronically ill – are less able to fight off infections than healthy people.
- Infections with other sexually transmitted pathogens: Herpes or chlamydia infections favor infection with HPV viruses.
How is CIN diagnosed?
Cell changes in the area of the cervix do not cause any noticeable symptoms. The gynecologist routinely checks for the presence of such changes during the annual screening exam.
PAP test
In order to detect cell changes in the cervix, the doctor performs a so-called PAP test. This involves taking a swab from the cervix using a cotton swab. This is then examined in a specialized laboratory for changes in the cells.
What does the result of the PAP test say?
PAP I: Normal, healthy cells, no indication of changes, next control in one year
PAP II: Slight cell changes (such as a harmless inflammation or a fungal infection), no suspicion of precancerous lesions or cancer, next control in one year
PAP III: Unclear findings, more pronounced inflammation or cell changes, further examinations necessary.
PAP IIID: Cell changes (dysplasia) are present, but no cancer. Further examinations are necessary.
PAP IV: Pre-cancerous lesions, early cancer or cancer are present. Further investigations are necessary for clarification.
PAP V: Evidence of malignant tumor cells, cancer is very likely.
Procedure depending on PAP findings
Vaginal endoscopy
If the result of the PAP test is PAP III or more, the doctor performs a vaginal endoscopy (colposcopy). During this procedure, he uses a special microscope and an attached camera to examine the mucous membrane of the cervix for changes. If there are any abnormalities, the doctor uses small forceps to take small tissue samples from the cervix (biopsy). These are then sent to a laboratory for microscopic examination.
Taking the tissue samples may cause mild pain, but usually takes only a short time. Until the wounds on the cervix have healed, there may be slight bleeding. It is therefore advisable to use panty liners in the days that follow.
HPV test
The HPV test determines whether an infection with HPV viruses is present. The procedure is similar to the PAP test: the doctor takes cells from the cervix with a brush. Some women find the examination uncomfortable and slightly painful.
The cells are then examined in the laboratory. This determines whether there is an infection with HP viruses at all and what type of virus it is:
- High-risk virus types: mainly HPV 16 and 18, but also HPV 31, 33, 35, 39, 45, 51, 52, 56, 58 and 59
- Low-risk virus types: mainly HPV 6 and 11, but also HPV 40, 42, 43, 44, 54, 61, 62, 70, 71, 72, 74, 81 and 83
How is CIN treated?
Treatment of CIN I
CIN I heals on its own in about half of women. If there are signs of inflammation caused by bacteria or fungi, the doctor treats these with appropriate medication. The next check-up with the gynecologist takes place in six months. If the HPV test is positive, this is followed by another vaginal endoscopy and, if necessary, a biopsy.
Treatment of CIN II
CIN 2 does not need to be treated immediately. It is usually sufficient to wait and check after six months by smear test how the cell changes have developed. If CIN II is still present after two years, doctors advise surgical removal of the change (conization).
Treatment of CIN III
In the case of CIN III, i.e. far advanced precancerous lesions, doctors advise immediate removal by conization.
What is a conization?
During a conization, the doctor removes the diseased tissue from the cervix. The procedure is performed under general or local anesthesia. To remove it, the doctor uses an electric heating loop (LEEP conization) or a laser and removes a cone-shaped piece of tissue from the cervix. In most women, conization leads to complete healing.
Refrain from sexual intercourse, baths and tampons for the first three to four weeks after the conization!
After conization, the doctor examines the patient again. A PAP test in combination with an HPV test offers good safety. A vaginal endoscopy is only necessary if the CIN has not been completely removed and/or the HPV test is still positive.
Is it possible to prevent CIN?
Cervical intraepithelial neoplasia is caused by HP viruses. Therefore, all measures that detect or, in the best case, prevent HPV infection at an early stage are suitable for prevention.
HPV vaccination
Two vaccines against human papillomaviruses are currently on the market. They prevent HPV infection and protect against cell changes that may become cervical cancer. Two vaccines are currently available:
- Dual vaccine: Protects against the high-risk HPV 16 and 18 types.
- Nine-dose vaccine: Protects against high-risk types 16, 18, 31, 33, 45, 52, and 58, and against low-risk types HPV 6 and 11 (additional protection against genital warts)
The HPV vaccine is a so-called dead vaccine. This means that the vaccine stimulates the immune system to produce antibodies, but cannot itself cause an infection.
In principle, vaccination is also possible at a later time (after the first sex). Even if an HPV infection with a certain virus type has already occurred, the vaccination still protects against the other virus types contained in the vaccine.
The vaccination is not suitable for treating an existing HPV infection. However, there is evidence that women who are vaccinated after conization are less likely to develop CIN again.
As with all vaccinations, side effects are possible after HPV vaccination. These include pain and swelling at the injection site, headache or dizziness. However, these immune system reactions are usually harmless and subside on their own within a few days.
Early detection examination
A CIN does not usually cause any symptoms. This makes it all the more important to take advantage of the annual preventive examinations at the gynecologist. This is because regular checks (PAP test) prevent cell changes from developing undetected into cervical cancer.
Since January 2020, women aged 35 and older can have a test for human papillomavirus every three years.
Even HPV vaccinated women should not forgo preventive examinations by their gynecologist, because the current vaccines so far prevent only part of the cancer-promoting HPV infections.
