The cervix is the opening of the uterus (womb) that leads into the vagina. In cervical dysplasia, abnormal cells develop on the surface of the cervix. These changes are now most often called squamous intraepithelial lesion (SIL). These abnormal cells are called lesions. Cervical dysplasia lesions can regress (which means they shrink and may even disappear), persist (the lesions remain present but don’t change), or progress to become a high-grade lesion or cervical cancer.
Changes in these cells can be divided into two categories.
• Low-grade SIL: Early, subtle changes in the size and shape of cells that form the surface of the cervix are considered low grade. These lesions may go away on their own, but over time, they may become more abnormal, eventually becoming a high-grade lesion.
• High-grade SIL: A large number of precancerous cells, which look very different from normal cells, constitute a high-grade lesion. Like low-grade SIL, these precancerous changes involve only cells on the surface of the cervix.
Although most HPV infections clear up on their own and most pre-cancerous lesions resolve spontaneously, there is a risk for all women that HPV infection may become chronic and pre-cancerous lesions progress to invasive cervical cancer. Cervical cancer is an abnormal growth of the cells of the cervix. It takes 15 to 20 years for cervical cancer to develop in women with normal immune systems. It can take only 5 to 10 years in women with weakened immune systems, such as those with untreated HIV infection.
In developed countries, programmes are in place which enable women to get screened, making most pre-cancerous lesions identifiable at stages when they can easily be treated. Early treatment prevents up to 80% of cervical cancers in these countries.