What causes cervical cancer?

A cancerous tumour starts from one cell. It is thought that something damages or alters certain genes in the cell. This makes the cell very abnormal and multiply 'out of control'. (See separate leaflet called 'What Causes Cancer' for more details.)

In the case of cervical cancer, the cancer develops from a cell which is already abnormal - see above. In most cases, abnormal cells are present for years before one of the abnormal cells becomes cancerous and starts to multiply out of control into a cancerous tumour. The initial 'pre-cancerous' abnormality of cervical cells is usually caused by a prior infection with the human papilloma virus.

Human papilloma virus (HPV virus) and cervical cancer

Most (possibly all) women who develop cervical cancer have been infected with a strain (sub-type) of the HPV virus at some point in their life. There are many strains of HPV virus. Some strains are associated with cervical cancer. (Note: some other strains of HPV cause common warts and verrucas. The strains of HPV which cause these common conditions are not associated with cervical cancer.)

In some women, the strains of HPV that are associated with cervical cancer seem to affect the cells which cover the cervix. This makes them more likely to become abnormal which may later (usually years later) turn into cancerous cells. But note: most women who are infected with these strains of HPV do not develop cancer. In most infections, the immue system deals with the virus and no harm results. It is only a small number of women who are infected with these strains of HPV that go on to develop abnormal cells, which then in some cases progresses into cervical cancer.

The strains of HPV virus associated with cervical cancer are nearly always passed on by having sex with an infected person. An infection with one of these strains of HPV does not usually cause symptoms. So, you cannot tell if you or the person you have sex with are infected with one of these strains of HPV.

Research trials are underway to test vaccines that have been developed against HPV. If infection against HPV can be prevented by a vaccine, then it is likely that cervical cancer will be prevented too.