Before they become cancerous, cells in the cervix go through a series of pre-cancerous changes.

These changes are not cancer, but if left untreated they may turn into invasive cancer of the cervix.

The name given to these abnormal, non-cancerous cells is cervical intra-epithelial neoplasia (or CIN). CIN can be detected through the cervical smear test, and can be treated before it turns into cancer.