What is cervical cancer?
Cervical cancer is the growth of abnormal cells in the lining of the cervix.
Cancer most commonly begins in the area of the cervix called the transformation zone, but it may spread to tissues around the cervix, such as the vagina, or to other parts of the body, such as the lungs or liver.
Topics on this page:
- The cervix
- Cervical cell changes
- Types of cervical cancer
- Who gets cervical cancer?
- What causes cervical cancer?
The cervix is part of the female reproductive system. The female reproductive system also includes the uterus (womb), ovaries, fallopian tubes, vagina and vulva (the external genitals).
Also called the neck of the uterus, the cervix connects the uterus to the vagina. It has an outer surface (lining) that opens into the vagina and an inner surface that faces into the uterus.
The functions of the cervix include:
- producing moisture to lubricate the vagina, which keeps the vagina clean
- producing mucus that helps sperm travel up to the fallopian tube to fertilise an egg that has been released from the ovary
- holding a developing baby in the uterus during pregnancy
- widening to enable a baby to be born via the vagina.
The cervix is covered by two kinds of cells:
Squamous cells – flat, thin cells that are found on the outer surface of the part of the cervix that opens into the vagina (ectocervix). Cancer of the squamous cells is called squamous cell carcinoma.
Glandular cells – column-shaped cells that are found on the inner surface of the cervix (cervical canal or endocervix). Cancer of the glandular cells is called adenocarcinoma.
Cervical cell changes
Sometimes the squamous cells and glandular cells in the cervix start to change and no longer appear normal when they are examined under a microscope. These changes are called precancerous lesions. This means there is a lesion (area of abnormal tissue) that is not cancer but may lead to cancer.
Cervical cell changes may be found during a routine screening test.
For some women, these precancerous lesions will disappear without treatment. Other lesions can be treated before they develop into cervical cancer. Treatment may include large loop excision of the transformation zone, laser surgery, a cone biopsy or dilation and curettage.
Only some women with precancerous changes of the cervix will develop cervical cancer.
There are different types of precancerous changes:
Atypia – The cervical cells have changed slightly. The cells may return to normal by themselves or the changes may worsen. If a cell shows signs of atypia, it does not necessarily mean you have cervical cancer or will get cancer. Atypia can be caused by an infection, such as HPV, or irritation.
Squamous abnormalities – The squamous cells of the cervix are abnormal. This abnormality may be classified as low grade or high grade. Low-grade abnormalities usually disappear without treatment. High-grade abnormalities are precancerous. Although they do not usually cause symptoms, high-grade abnormalities in the cervix have the potential to progress to early cervical cancer over about 10–15 years if they are not detected and treated.
Squamous abnormalities are also called cervical intraepithelial neoplasia (CIN). They are graded according to how deep the abnormal cells are within the surface of the cervix. This is detected by taking a sample of tissue (biopsy) from the surface of the cervix. Early changes are graded as CIN 1, and they will usually disappear without treatment. Further abnormal changes are graded as CIN 2 or CIN 3 and will require treatment.
Glandular abnormalities – The glandular cells of the cervix are abnormal. These abnormalities always require further testing, as they may be either precancerous or cancerous.
If the results from a screening test show that your cervix has any of the abnormal changes described above, your doctor will recommend one of the following options depending on the grade of the changes:
Types of cervical cancer
There are two main types of cervical cancer, which are named after the cells they start in:
Adenocarcinoma – a less common type, starting in the glandular cells of the cervix. Adenocarcinoma is more difficult to diagnose because it occurs higher up in the cervix and is harder to reach with the instruments a doctor uses during a screening test.
A small number of cervical cancers 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 and cervical sarcoma.
Who gets cervical cancer?
About 800 women in Australia are diagnosed with cervical cancer every year. Cervical cancer accounts for about 1.5% of all cancers diagnosed in women.
The incidence of cervical cancer in Australia has decreased significantly since a national screening program was introduced in the 1990s.
What causes cervical cancer?
Most cases of cervical cancer are caused by an infection called human papillomavirus (HPV). There are also other known risk factors (see below).
HPV – Human papillomavirus is the name for a group of viruses. HPV is a common infection that affects the surface of different areas of the body, such as the cervix, vagina and skin.
There are more than 100 different types of HPV, including more than 40 types of genital HPV. Some types of HPV cause common warts on the hands and feet.
Genital HPV is usually spread via the skin during sexual contact. About four out of five people will become infected with genital HPV at some time in their lives. Most people will not be aware they have HPV as it is usually harmless and doesn’t cause symptoms.
In most women, the virus is cleared quickly by the immune system and no treatment is needed.
Only a few types of genital HPV cause cervical cancer. Screening tests are used to detect these types of HPV or the precancerous cell changes caused by the virus. There is also a vaccination against HPV.
Smoking and passive smoking – Chemicals in tobacco can damage the cells of the cervix, making cancer more likely to develop in women with HPV.
Weakened immune system – The immune system helps the body get rid of HPV. Women with a weakened immune system are at increased risk of cervical cancer. This includes women with HIV (the virus that causes AIDS) and women who take medicines that lower their immunity. Ask your doctor if this applies to you.
Taking an oral contraceptive (the pill) – Research has shown that women who have taken the pill for five years or more are at increased risk of developing cervical cancer.
The reason for this is not clear. However, the risk is small and the pill can help protect against other types of cancer, such as uterine and ovarian cancers. Talk to your doctor if you are concerned.
Diethylstilbestrol (DES) exposure – DES is a synthetic (artificial) form of the female hormone oestrogen. DES was prescribed to pregnant women from the 1940s to the early 1970s to prevent miscarriage.
Studies have shown that the daughters of women who took DES have a small but increased risk of developing a rare type of cervical adenocarcinoma.