Warts are caused by viruses, called human papillomaviruses (HPV). Most papillomaviruses, like the ones that cause common skin warts (verruccae vulgaris), are benign. Warts almost always go away by themselves because the body's immune system eventually recognizes the infected tissue, mounts an attack and rejects them, leaving clear skin and no trace of the wart.

But all papillomaviruses are not the same and the diseases they cause don't always go away by themselves. Of the hundred or so papillomaviruses that cause infections in humans, several cause venereal warts (condyloma accuminatum) and some can even cause cancer. Human papillomavirus-16 (HPV-16) and human papillomavirus-18 (HPV-18) are the most common high-risk types that can cause cancers if left untreated. Together, HPV-16 and HPV-18 cause about 70% of cervical cancers.

Cancer of the cervix is diagnosed in about 1500 Canadian women every year and causes around 380 deaths annually. These numbers were higher in the mid-20th century before routine screening using Papinocolaou smears, or "Pap tests," was initiated, mainly in the western world. Cervical cancer remains more common in third world countries. It is a disease associated with sexual activity. The younger a woman is when she becomes sexually active, and the greater the number of sex partners she has, the greater her risk of cervical cancer.

Other risk factors include smoking, multiparity (giving birth many times), weak immune system, use of oral contraceptives rather than barrier methods, and low socioeconomic status. The male sex partner serves as the vector for transmitting the virus, so sex with a male who had a previous partner with papillomavirus infection results in increased risk for papillomavirus infection and cervical cancer. There is an increased susceptibility to papillomavirus infection during pregnancy, if someone is immunocompromised with diabetes or HIV infection or after local trauma to the genital area.

The majority of women diagnosed with cancer of the cervix have not had a Pap test performed for several years.

Screening for cervical cancer using Pap tests can reduce the number of cases of cervical cancer. All women who are sexually active should have the Pap test every 1 to 3 years, depending on their test results and provincial guidelines.

Pap tests have proven themselves as one of the most effective methods of cancer prevention in women. If you are a woman who has had one or more sexual partners, make sure you get regular pap tests.

In addition, there are HPV vaccines available for prevention in Canada. Gardasil® is a vaccine used in females and males for the prevention of certain diseases caused by HPV. The strains covered are 6, 11, 16, and 18. Gardasil-9®, also used in both females and males, covers 9 types of HPV strains: 6, 11, 16, 18, 31, 33, 45, 52, and 58. Cervarix® is another vaccine for prevention of cervical cancer. It is currently approved for females only and covers 2 types of HPV strains: 16 and 18.

The vaccines are safe and have demonstrated high effectiveness in preventing HPV-related infection and cancer.

Ray Baker, MD
updated by the MediResource clinical team
Ray Baker, MD