Cervical Cancer: HPV, Pap Smear Screening, and Prevention Explained

In short: The main cause of cervical cancer is the human papillomavirus (HPV); types 16 and 18 are responsible for 70% of cases. It can be prevented by regular cervical smear tests, one of the most successful screening tests in medicine. Early changes are treated by laser, freezing or removal. See the doctor at once for any abnormal bleeding.

Human Papillomavirus (HPV) is the main cause of most of the tissue changes that affect the female reproductive tract, including the vagina, cervix, external genitalia, and the anus.

Persistent infection with high-risk HPV types is the cause of almost all (more than 95%) cervical cancers, which is why understanding it is so important for your health.

Human Papillomavirus (HPV)

HPV is a DNA virus that infects the skin and mucosal membranes. There are more than 100 types of HPV, and some cause skin polyps — which is why it’s named a “papillomavirus.” It spreads through skin-to-skin contact, and around 30 types are transmitted sexually. Genital HPV is very common, infecting around 75% of women in Western countries at some point during their lifetime.

General characteristics of Human Papillomavirus

• It’s part of the papillomaviridae family and can become fully integrated with the DNA of the host cell. Humans are the only known source of this virus.
• There are more than 100 types of HPV with different DNA sequences. A specific group known as genital HPV is considered dangerous, especially HPV 16, 18, 31, 45, 58, along with HPV 33, 35, 39, 51, 52, 56, 59, 68, 73, and 82, which are known risk factors for cervical cancer development.

Signs and symptoms of infection with Human Papillomavirus:

• Skin polyps:
• • Common warts
• Plantar warts
• Flat warts, found mainly on the arms, face, and forehead.
• Nail warts
• Anogenital warts (condylomata acuminata):

90% of cases are caused by HPV 6 and 11. Usually, the infection resolves spontaneously without any warts or other signs or symptoms. It’s worth noting that the virus types that cause genital warts don’t cause cervical cancer.

• Respiratory papillomatosis:

HPV types 6 and 11 can cause a rare condition called recurrent respiratory papillomatosis, in which warts form in the larynx and other parts of the trachea. These warts can recur multiple times, sometimes requiring several surgeries, and can affect breathing. In extremely rare cases, this may progress to cancer.

• Cancers related to HPV:

About 12 types of HPV are classified as high-risk, including HPV 16, 18, 31, 33, 45, 52 and 58, because of their strong association with cervical, anal, and vaginal cancer, as well as head, neck, and penile cancer. These types carry genes such as E6 and E7, which are linked to tumor growth and malignant transformation.

Methods of spread of Human Papillomavirus and prevention:

Most people are exposed to some cutaneous HPV types during childhood. HPV has a protein shell that allows it to survive on surfaces for extended periods, so avoiding contact with shared surfaces such as public toilet floors may help lower the risk of cutaneous infection. Genital infection spreads through skin and mucosal contact and can be asymptomatic. Several strategies can help reduce the risk of diseases linked to genital HPV.

• HPV Tests:

This test detects the genetic material (DNA) of HPV. Like the Pap smear, it’s performed on cervical cells and can be done at the same time. It’s recommended for:

• • Women who had atypical squamous cells on a Pap smear, to check for high-risk HPV types. If high-risk HPV is detected, further steps such as colposcopy or cervical biopsy may be recommended.
• All women from age 25-30 as the main (primary) cervical screening test, repeated every 5 years if negative (the WHO recommends every 5-10 years from age 30). In many programmes women can collect the sample themselves with a vaginal swab.

Modern HPV tests detect the high-risk HPV types and report HPV 16 and 18 separately. Women with HPV 16 or 18 are usually referred directly for colposcopy, while those with other high-risk types have a Pap (cytology) test to decide the next step. Testing for low-risk types (such as 6 and 11) is not useful for screening.

• HPV vaccine:
• • Several HPV vaccines are available, including Gardasil 9, Gardasil and Cervarix. All protect against HPV-16 and HPV-18, which cause about 70% of cervical cancers and most HPV-related anal cancers. Gardasil 9 also protects against five further high-risk types (31, 33, 45, 52, 58), covering about 90% of cervical cancers, and against HPV-6 and HPV-11, which cause 90% of genital warts.
• For girls and young people aged 9-14 (and up to 20 in many countries), one or two doses are enough; older individuals usually receive two or three doses, and people with weakened immunity (such as HIV) need three doses.
• It’s recommended for girls (and in many countries also boys) aged 9 to 14, and can be given to anyone up to age 26 who hasn’t been vaccinated. Women aged 27 to 45 may still benefit and can discuss it with their doctor, although the benefit is smaller; regular cervical screening remains essential at all ages.
• Ideally, the vaccine is given before girls become sexually active and before HPV exposure. It can still be given to women who are already sexually active, though the benefit may be reduced if they’ve already been exposed to some of the HPV types covered.
• It’s not recommended during pregnancy. While studies suggest no harm to the baby, more research is needed. Receiving the vaccine during pregnancy is not a reason to end the pregnancy.
• The vaccine doesn’t protect against all types of cervical cancer (around 10-30% are not covered, depending on the vaccine), so it remains important to continue regular cervical screening even after vaccination.
• Other ways to help prevent HPV:
• • Use condoms consistently and correctly during sexual activity, though HPV can still infect areas not covered by a condom, so protection is not complete.
• Being in a mutually faithful relationship with one partner.
• Choosing a partner with few or no prior sexual partners.
• The only certain way to avoid HPV is to avoid all sexual activity.
• Avoid smoking, as it increases the risk of cervical cancer.

Pap smear

The Papanicolaou test (Pap smear) is a screening test used to detect precancerous changes (cervical intraepithelial neoplasia, CIN, or cervical dysplasia) and cancerous changes in the cervix, usually caused by sexually transmitted HPV. It can also help detect infections and abnormalities in the cervix and endometrium.

• Indications for Pap smear:
• • Screening generally starts around age 21 to 25 (this varies by country) and continues until about age 65. It’s recommended every three years with a Pap smear alone, or every five years with an HPV test, if previous results were normal, with more frequent testing after abnormal results.
• It should not be done before age 21, and it’s best to wait a few years after first intercourse before starting screening. If HPV is acquired after becoming sexually active, the immune system usually takes 1 to 4 years to control the infection, so early screening may show mild, temporary abnormalities related to this immune response rather than true cervical disease — which can cause unnecessary worry and additional testing. Since cervical cancer usually develops slowly, this brief delay carries very little risk of missing a precancerous lesion.
• Pap smears are still recommended even for women who received the HPV vaccine, since the vaccine doesn’t cover all cancer-causing HPV types.
• Screening is generally not needed for:
• • Women who have never had sexual contact.
• Women over 65 who have had regular normal screening results in the previous 10 years (for example 3 normal Pap smears or 2 normal HPV tests, the last within 5 years) and no history of high-grade changes.
• Women who have had a complete hysterectomy for benign (non-cancerous) disease.
• Types of Pap smear:
• • Conventional Pap: the collected sample is smeared directly onto a microscope slide.
• Liquid-based Pap: the sample is placed in a liquid preservative before being transferred to a slide in the lab.
• How the Pap smear is performed:
• • A speculum is gently inserted into the vagina to allow access to the cervix. A sample of cells is collected from the outer surface of the cervix using a small spatula, and an endocervical brush is rotated inside the cervical opening. The collected cells are placed on a glass slide and sent to the lab.
• It’s best to avoid Pap smears during menstruation, since blood and endometrial cells can obscure the cervical cells.
• The procedure is not painful, and a small amount of water-based lubricant does not affect the results.
• The sample is stained using the Papanicolaou technique.

Position for taking cervical smear

• Results:
• • Most Pap smear results are normal.
• 2-5% show mild abnormalities, including:
• ASC-US: atypical squamous cells of undetermined significance.

LSIL (CIN 1): low-grade squamous intraepithelial lesion.

• Both usually indicate HPV infection.
• Most low-grade cervical dysplasia resolves on its own without progressing to cancer, but follow-up is still important.
• About 0.5% of cases show high-grade SIL (HSIL) (CIN2/3), a higher-grade cervical intraepithelial lesion.
• Less than 0.5% indicate cancer (squamous cell carcinoma).
• 0.2%-0.8% show Atypical Glandular Cells of undetermined significance (AGC-NOS).

Normal PAP smear Abnormal PAP smear

Cervical intraepithelial neoplasia:

CIN is a precancerous change in cervical cells and is not cancer itself. Most CIN cases remain stable or resolve naturally through the body’s immune response. A small percentage of cases may progress to cervical cancer if left untreated.

The most common cause of CIN is HPV, especially types 16 and 18. It’s diagnosed through Pap smear screening, and if results are abnormal, a colposcopy of the cervix is usually recommended.

• Classification of Cervical intraepithelial neoplasia:

Candidiasis in a pap smear

• • CIN 1 (LSIL):
• • Mild dysplasia limited to the basal one-third of the epithelium.
• Caused by HPV infection.
• Usually cleared by the immune system within a year or more.
• CIN 2/3 (HSIL):
• • CIN2: moderate dysplasia involving the basal two-thirds of the epithelium.
• CIN3: severe dysplasia involving more than two-thirds of the epithelium, sometimes the full thickness — referred to as cervical carcinoma in situ.
• Treatment of Cervical intraepithelial neoplasia:
• • CIN1 usually needs no treatment if it lasts less than 2 years.
• Higher-grade CIN typically requires treatment to remove or destroy abnormal cells, such as cervical conization, laser therapy, loop electrical excision, electrocautery, or cryocautery.

• Colposcopy:
• • This diagnostic procedure allows your doctor to examine a magnified view of the cervix to distinguish normal from abnormal tissue, and to take targeted biopsies from any abnormal areas for pathology testing.

-Indications for Colposcopy:

• • Pap smear shows abnormalities suggesting cervical dysplasia or cancer.
• A positive test for HPV 16 or 18, or another high-risk HPV type together with an abnormal Pap smear, or persistent high-risk HPV on repeat testing.
• Repeated atypical squamous cells of undetermined significance (ASCUS) on Pap smear.
• History of prenatal DES exposure.
• If the cervix appears abnormal during Pap smear collection.
• It’s a simple procedure that doesn’t require anesthesia and takes about 10 minutes.

-How colposcopy is performed:

• • The vulva and vagina are first examined for warts or other abnormal growths. Then a speculum is inserted, and a Pap smear may be taken.
• The cervix is then examined, with special attention to the squamocolumnar junction — the area where most cervical cancers arise, located between the squamous and columnar cells of the endocervical canal. After menopause, this junction tends to move further inside the canal, making colposcopy less reliable; other techniques such as cold knife biopsy may be used instead in these cases.
• • Tests performed during colposcopy:
• Acetic acid wash: a diluted solution (3%-5%) used to cleanse the cervix and highlight abnormal areas, which turn white (acetowhite lesions). Some normal areas may also whiten slightly but typically have faint borders, while abnormal areas have clearer borders.
• Lugol’s iodine staining: a diluted iodine solution that stains normal cells brown, while abnormal areas remain unstained, helping to distinguish between them.
• Color filters: green or blue filtered light can help highlight abnormal blood vessels within acetowhite areas, which may appear as red dots or a hexagonal tile-like pattern, compared to the slender, evenly spaced vessels seen in normal tissue.
• Cervical biopsy: samples are taken from abnormal areas, and treatment is planned based on the biopsy results.
• Treatment based on colposcopy findings:
• Treatment is generally recommended if the biopsy shows precancerous changes or cancer.
• There are two main treatment types — ablation and resection — both of which are effective for most precancerous (CIN2/3) lesions; mild dysplasia usually only needs follow-up.
• Ablation (destruction of abnormal tissue) can be used for precancerous changes when the whole abnormal area is clearly visible, and includes thermal ablation, CO2 laser ablation and cryocautery.
• Resection (removal of abnormal tissue) is used for more advanced dysplasia or cancer and includes loop electrosurgical excision procedure (LEEP), cold knife conization, and hysterectomy.
• CO2 laser ablation: vaporizes the abnormal area; complications such as cervical stenosis or delayed bleeding occur in less than 1% of cases.
• Cryocautery: freezes abnormal areas using nitrous oxide; complications such as cervical stenosis or delayed bleeding occur in less than 1% of cases.
• Loop electrosurgical excision procedure (LEEP): uses radiofrequency current to remove abnormal tissue; complications occur in 1-2% of cases, including cervical stenosis and bleeding.

Excision treatments (LEEP and cone biopsy) slightly increase the risk of preterm birth in future pregnancies, especially when a deep piece is removed, so the smallest effective treatment is used in young women. A follow-up HPV test about 6 months after treatment checks that the problem has cleared.

• Cone biopsy: used when the abnormal area can’t be fully seen during colposcopy, or to obtain deeper tissue samples in more advanced cases. It carries a higher complication rate than other procedures — around 5% of cases may involve post-op bleeding or cervical narrowing.
• Hysterectomy: surgical removal of the uterus, occasionally performed for recurrent precancerous changes when further cone treatment is not possible. Early invasive cervical cancer is usually treated with radical hysterectomy, and more advanced cancer with combined chemotherapy and radiotherapy.

electro - surgical loop ( LLETZ ) -

Cervical biopsy

Cone biopsy

PAP and Colposcope Cervical Changes

If you have questions about HPV, Pap smear screening, or cervical health, Dr. Najeeb Layyous and his clinical team are available to guide you through personalized evaluation and care.

Dr Najeeb Layyous F.R.C.O.G

Consultant Obstetrician, Gynecologist and Infertility Specialist