In almost all cases, cervical cancer is the result of a change in cell DNA caused by the human papilloma virus (HPV).
Cancer begins with a change in the structure of the DNA that’s present in all human cells. DNA provides the cells with a basic set of instructions, including when to grow and reproduce.
A change in the DNA’s structure is known as a mutation. It can alter the instructions that control cell growth, which means the cells continue growing instead of stopping when they should. If the cells reproduce uncontrollably, they produce a lump of tissue called a tumour.
Human papilloma virus (HPV)
More than 99% of cervical cancer cases occur in women who have been previously infected with HPV. HPV is a group of viruses, rather than a single virus. There are more than 100 different types.
HPV is spread during sexual intercourse and other types of sexual activity (such as skin-to-skin contact of the genital areas, or using sex toys) and is thought to be very common. It’s estimated that 1 in 3 women will develop a HPV infection within two years of starting to have regular sex, and about 4 in 5 women will develop the infection at some point in their lives.
Some types of HPV don’t cause any noticeable symptoms and the infection will pass without treatment. Other types of HPV can cause genital warts, although these types aren’t linked to an increased risk of causing cervical cancer.
About 15 types of HPV are considered high-risk for cervical cancer. The two types known to have the highest risk are HPV 16 and HPV 18, which cause about 7 out of every 10 cervical cancers.