What causes cervical cancer?

Cervical cancer (cancer of the cervix) is a cancer that develops in a woman’s cervix. The cervix is the entrance to the uterus (womb) from the vagina.

What is cervical cancer?

Over time the cells of the cervix change and in some cases the changed cells can become cancerous.

Cervical cancer is the second most common cancer experienced by women worldwide. In Australia every year, around 800 women are diagnosed with cervical cancer.

It can be prevented by regular cervical screening tests to detect any trace of HPV, which can lead to changes in the cells in the cervix.

There are two forms of cervical cancer:

  • Squamous cell carcinoma (80-85% of cases)  
  • Adenocarcinoma (12-15% of cases).

Cancer of the cervix is very rare in women under the age of 25; it mostly occurs in women aged 55-60.

What causes cervical cancer?

Cervical cancer is almost always caused by the human papillomavirus (HPV).

HPV is a common sexually transmitted infection that affects the surface cells of the genital area including the cervix, vagina and vulva. It can also cause visible warts.

HPV is very common in women aged 20-30 and four out of five women will be exposed to the virus at some point in their lifetime. While HPV is common, most women with the infection do not go on to develop cervical cancer. Only certain types of HPV cause cancer.

Cervical cancer usually occurs many years after the infection caused by the HPV virus.

What increases your risk of cervical cancer?

  • Smoking
  • Not having regular cervical screening tests
  • Age (more common in women over 35 years)
  • Exposure in utero to Dethylstilbestrol (DES), a drug given to women from the 1940s-1970s to prevent miscarriage, which increased the risk of the rare clear cell adenocarcinoma of the vagina and cervix (1.5 cases per 1000 women born between 1938-1974, exposed when their mothers were pregnant and given DES).

Cervical cancer, especially in the early stages, may not have any obvious symptoms. In most cases vaginal bleeding (often following sex) is the first noticeable symptom of cervical cancer, so this should always be discussed with a doctor.

If abnormal or cancerous cells are detected from further investigation after cervical screening, your doctor will refer you to a specialist, usually a gynaecologist who specialises in cancer treatment.

Prevention of cervical cancer: the cervical cancer vaccine  

Because most cervical cancers are caused by the human papillomavirus (HPV), one form of prevention involves vaccination against the virus. There are different types of HPV and there are three types of cervical cancer vaccines – GardasilTM, CervarixTM and Gardasil 9TM – to protect against these.

Vaccine Protection against HPV type Use Cost
Gardasil 9TM 6, 11, 16, 18, 31, 33, 45, 52 & 58

This will provide protection against 90% of cervical cancers

From 2018, all 12 & 13 year-old boys & girls in schools Free under Australian Government vaccination program
GardasilTM 6, 11, 16 & 18Types 6 & 11 are known to cause up to 90% of genital warts.

Types 16 & 18 cause around 70% of cervical cancer cases

Approved for use in females aged 9-26.

It is recommended girls have the vaccine between ages 9-12.

Best given before becoming sexually active

Free to all Year 7 girls under Australian Government vaccination program
CervarixTM 16 & 18

Types 16 & 18 cause around 70% of cervical cancer cases

Approved for use in women aged 27-45 years Not covered by Australian Government vaccination program
Do you still need to have cervical screening tests if you have had the vaccine? 

Even if you have had the HPV vaccine (either before or after becoming sexually active), you need to continue to have regular cervical screening tests every five years because the HPV vaccine only protects you from 70-90% of cervical cancers.

Prevention of cervical cancer: detection of cervical changes

Regular screening can prevent 9 out of 10 cervical cancers. Most women diagnosed with cervical cancer have not had regular cervical screening tests.

Read more about screening and the cervical screening test on our Health checks webpages.

Does an abnormal test result mean cervical cancer? 

The Cervical Screening Test began on 1 December 2017, replacing the Pap smear test. The new test screens for the presence of the human papillomavirus (HPV) and looks for HPV types 16 and 18 and other high-risk for types for women aged 25-74 years of age.

If HPV 16 or 18 are detected:

the cells in the specimen will be looked at for HPV cell changes and the woman will be referred for a colposcopy. A colposcopy is usually an outpatient procedure, in which the cervix is looked at through a microscope to magnify the areas of abnormal cells so a biopsy (sample) can be taken to identify the changes in the cells. The procedure is usually performed by a gynaecologist.

If the high-risk HPV is detected: 

the cells of the sample will be checked for HPV cell changes. If negative, then the HPV test will be repeated in 12 months.

If the sample shows HPV changes, but possible or low-grade changes:

then the HPV test is repeated in 12 months.

If the sample shows possible or high-grade cell changes:

then the woman is sent for a colposcopy.

If the HPV test is unsatisfactory:

a new sample is collected in 6-12 weeks.

If the HPV test detects high risk or non-16/18 types, but the cytology (examination of the cells under a microscope) is unsatisfactory:

a further sample is taken in 6-12 weeks.

If the test does not detect the HPV virus:

screening is repeated in five years.

Current terminology to describe cervical changes

  • Squamous intraepithelial lesion (SIL): low grade and high grade
  • ‘squamous’ describes the type of cell on the surface lining of the cervix
  • ‘intraepithelial’ describes the HPV changes within those cells

The progression from high-grade changes to cancer takes between one and 30 years with an average of 10 years. This is why it is important to have regular cervical screening tests and have abnormal changes picked up as early as possible.

Treatment for precancerous changes in the cervix after colposcopy

Your gynaecologist will discuss the treatment options with you. Treatment options for any confirmed high-grade lesions include:

  • laser therapy
  • electrocoagulation (high frequency electrical current)
  • loop excision
  • removal of a larger area on the cervix, such as a cone biopsy.
Treatment for cervical cancer

This depends on the size and type of cervical cancer but can include:

  •  surgery
  • radiotherapy
  • chemotherapy.

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