Cervical cancer occurs when cells in the cervix grow out of control. A group of abnormal cells together can form a malignant (cancerous) tumor.
Cervical cancer usually develops slowly over time. Before cancer appears in the cervix, the cells of the cervix go through changes known as dysplasia, in which cells that are not normal begin to appear in the cervical tissue. Later, cancer cells start to grow and spread more deeply into the cervix and to surrounding areas.
Almost all cases of cervical cancer are caused by a virus called Human Papillomavirus (HPV). HPV can cause cells in the cervix to grow abnormally and become cancerous.