Cervical cancer begins when abnormal cells in the lining of the cervix grow uncontrollably.
Cancer most commonly starts in the area of the cervix called the transformation zone. It may then spread to tissues around the cervix, such as the vagina, or to other parts of the body, such as the lymph nodes, lungs or liver.
Learn more about:
The cervix
The cervix is part of the female reproductive system, which also includes the ovaries, fallopian tubes, uterus (womb), vagina (birth canal) and vulva (external genitals).
What the cervix does
The cervix connects the uterus to the vagina. The cervix:
- produces fluid to help keep the vagina healthy
- opens to let menstrual blood pass from the uterus into the vagina
- produces mucus that helps sperm travel up through the uterus and fallopian tubes to fertilise an egg that has been released from an ovary
- holds a developing baby in the uterus during pregnancy by remaining closed, then widens to allow a baby to be born through the vagina.
Where cervical cancer starts
The cervix has an outer surface that opens into the vagina (ectocervix) and an inner surface that lines the cervical canal (endocervix).
These surfaces are covered by 2 types of cells:
- Squamous cells – flat, thin cells that cover the outer surface of the cervix (ectocervix). Cancer of the squamous cells is called squamous cell carcinoma.
- Glandular cells – column-shaped cells that cover the inner surface of the cervix (cervical canal or endocervix). Cancer of the glandular cells is called adenocarcinoma.
The area where the squamous cells and glandular cells meet is known as the transformation zone. This is where most cervical cancers start.
The female reproductive system
Types of cervical cancer
There are 2 main types of cervical cancer:
- squamous cell carcinoma (SCC) – the most common type (about 6 out of 10 cases), starts in the squamous cells of the cervix
- adenocarcinoma – a less common type (about 3 out of 10 cases), starts in the glandular cells of the cervix. Adenocarcinoma is more difficult to diagnose because it occurs higher up in the cervix and the abnormal glandular cells are harder to find.
A small number of cervical cancers (less than 1 in 20 cases) feature both squamous cells and glandular cells. These cancers are known as adenosquamous carcinomas or mixed carcinomas. Other rarer types of cancer that can start in the cervix include small cell carcinoma, clear cell adenocarcinoma and cervical sarcoma.
Who gets cervical cancer?
Anyone with a cervix can get cervical cancer – women, transgender men and people with an intersex variation. Each year in Australia, about 960 women are diagnosed with cervical cancer.
Cervical cancer is most commonly diagnosed over the age of 30 years. More than half of all cervical cancer cases occur in those aged 30–49 years, but it can occur at any age.
Diagnoses of cervical cancer in Australia reduced significantly after a national screening program was introduced in the 1990s. The introduction of a national human papillomavirus (HPV) vaccination program in 2007 and improvements to the screening program in 2017 are expected to further reduce rates of cervical cancer.
What causes cervical cancer?
Almost all cases of cervical cancer are caused by an infection with the human papillomavirus (HPV). Read more about other known risk factors.
Infection with HPV
HPV is the name for a group of viruses. Infection with HPV is common. It affects the surface of different areas of the body, such as the cervix, vagina and skin. Some types of HPV cause cancer, while others can cause common warts on the hands and feet.
There are more than 100 different types of HPV, including over 40 types that can infect the genitals. Genital HPV is usually spread during close contact with genital skin during sexual activity. This includes penetrative sex as well as oral sex and other forms of sexual activity (e.g. using sex toys). Using condoms or dental dams offers some protection against HPV.
About 4 out of 5 people will become infected with at least one type of genital HPV at some point in their lifetime. Most people will not know they have HPV because it doesn’t cause symptoms. In most people, the virus is cleared quickly by the immune system and no treatment is needed. If the infection doesn’t go away, there’s an increased risk of developing changes in the cervix. These changes usually develop slowly over many years.
Fourteen types of genital HPV are known to cause cervical cancer. The cervical screening test is used to detect most of these types of HPV and the precancerous cell changes caused by the virus. For more on this see screening. There is also a vaccine that protects people from some types of HPV (see below).
National HPV vaccination program
Vaccination can prevent infection with HPV. The most common HPV vaccine used in Australia protects against 7 high-risk types of HPV known to cause about 9 out of 10 cervical cancers, as well as 2 types of HPV that cause most genital warts. The vaccine also offers some protection against less common cancers linked with HPV, including vaginal, vulvar and anal cancers.
Under the national HPV vaccination program, free vaccines are provided at school for all children aged 12–13.
If you weren’t vaccinated at school, and are aged 45 years or under, ask your doctor if you may benefit from having the vaccine. Even if you have been vaccinated against HPV, you will need regular screening tests as the HPV vaccine does not protect against all types of HPV.
The HPV vaccine does not treat cervical cancer or precancerous cell changes.
For more information, visit hpvvaccine.org.au.
What are the other risk factors?
Other factors that may increase the risk of developing cervical cancer include:
- Smoking and passive smoking – Chemicals in tobacco can damage the cells of the cervix, making it harder for the body to clear the HPV infection.
- Using oral contraceptives (the pill) for a long time – Research has shown that taking the pill for 5 years or more increases the risk of developing cervical cancer in people with HPV. The reason for this is unclear, and the risk is small. However, the pill can help protect against other types of cancer, such as cancer of the uterus and ovarian cancer. Talk to your doctor if you are concerned.
- Having a weakened immune system – The immune system helps rid the body of HPV. In some people, a weakened immune system can increase the risk of developing cervical cancer, so more frequent cervical screening tests may be needed. This includes people with human immunodeficiency virus (HIV) and those who have had an organ transplant.
→ READ MORE: Cervical cancer symptoms
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Prof Martin Oehler, Director of Gynaecological Oncology, Royal Adelaide Hospital, and Clinical Professor, University of Adelaide, SA; Dawn Bedwell, 13 11 20 Consultant, Cancer Council QLD; Gemma Busuttil, Radiation Therapist, Crown Princess Mary Cancer Centre, Westmead Hospital, NSW; Dr Antonia Jones, Gynaecological Oncologist, The Royal Women’s Hospital and Mercy Hospital for Women, VIC; Angela Keating, Senior Psychologist, Royal Hospital for Women, NSW; Anne Mellon, Clinical Nurse Consultant – Gynaecological Oncology, Hunter New England Centre for Gynaecological Cancer, NSW; Dr Inger Olesen, Medical Oncologist, Andrew Love Cancer Centre, Barwon Health, Geelong, VIC; Dr Serena Sia, Radiation Oncologist, Fiona Stanley Hospital and King Edward Memorial Hospital, WA; A/Prof Megan Smith, Co-lead, Cervical Cancer and HPV Stream, The Daffodil Centre, Cancer Council NSW and The University of Sydney, NSW; Emily Stevens, Gynaecology Oncology Nurse Coordinator, Southern Adelaide Local Health Network, Flinders Medical Centre, SA; Melissa Whalen, Consumer.
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