Human papillomavirus (HPV) infection is the most important risk factor for cervical cancer. Certain types of HPV are linked with around 95% of all cases of cervical cancer. HPV is a group of over 90 viruses that cause warts in a variety of places on the body, including the cervix. Those that affect the genital tract are usually spread sexually.
Cervical strains of HPV are divided into ‘high risk’ and ‘low risk’ categories based on their association with cervical cancer. HPV 6 and HPV 11, for instance, cause most cases of genital warts but are considered ‘low risk’ because they rarely lead to cancer. Other HPV strains, such as HPV 16, 18, 31, and 33 are considered ‘high risk’ because they have been linked with an increased risk for cervical and vaginal cancer.
You may hear that women who have many sex partners or women who started having sex young are more likely to get cervical cancer. This is only true because such activities increase the likelihood of picking up an infection with a ‘high risk’ human papilloma virus (HPV). It is not correct to say that women who get cervical cancer have it because they were promiscuous (slept around) - you could have only slept with one man and still caught the virus and not all women with cervical cancer have the virus anyway.
Weakening of the immune system through smoking, poor diet or other infections may permit CIN to develop into cancer. Smoking suppresses the immune system and may damage the DNA in the cells of the cervix. Smokers are about twice as likely as nonsmokers to get cervical cancer.