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1. Predisposing Factors/Risk Factors

 

Updated February 2018

Cancer of the uterine cervix is the 13th most common cancer in Canadian women, with an estimated 1500 new diagnoses in 2016. About 400 women will die from the disease per year. The most common histologic types of cervical cancer are squamous cell carcinomas, which arise in the ectocervix (70%), and adenocarcinomas or adenosquamous carcinomas arising in the endocervical canal (25%).  

Known Risk Factors

Human papillomavirus (HPV): HPV is the most common sexually transmitted disease and is the major factor causally associated with cervical cancer. HPV is a group of more than 100 different types of viruses, of which at least 13 types are known carcinogens. HPV-16 and -18 cause 70% of the cervical cancers and precancerous cervical lesions4. High-risk groups include women who have less access to Pap tests or women who have never participated in screening programs.

Smoking: women who smoke are at increased risk of developing cervical cancer. Tobacco by-products may contribute to cervical cancer by either local DNA damage or local immunosuppression and reduced immune response to HPV infection5

Human immunodeficiency virus (HIV): HIV infection in women appears to elevate risk of cervical cancer due to immunosuppression6.

Diethylstilbestrol (DES): this is a form of estrogen that was used from 1940 to 1971 for treatment of certain conditions during pregnancy such as miscarriages. Daughters of women who took this medication during their pregnancy are at higher risk of developing clear cell carcinoma of cervix or vagina. DES daughters may also be at increased risk of cervical squamous cell carcinoma development if they had exposure to HPV. 

Possible Risk Factors

Sexually transmitted infections: some studies demonstrated higher risk of cervical squamous cell cancer with past or current chlamydia or herpes simplex virus type 2 infections8. More research is required to clarify the role of these infections for cervical cancer.

Family history of cervical cancer: there is some evidence that women with family history of cervical cancer have higher chance of cervical cancer diagnosis compared to women without a family history9. However, more studies are required to clarify whether this is due to genetics or having higher motivation for screening and health protective behaviors.

Obesity: observational studies reported no association between cervical cancer and being overweight. But obesity was weakly associated with an increased risk of cervical cancer10. More research is required to provide conclusive evidence in this regard.

Prevention

HPV vaccines: these vaccines are powerful tools to diminish the rate of HPV-associated cancers including cervical, oropharyngeal, anal, vulvar, vaginal and penile malignancies. Three HPV vaccines have been developed and approved for use by Health Canada:

Cervarix® (HPV2) 
[against HPV types 16 and 18]

Gardasil® (HPV4) 
[Human Papillomavirus quadrivalent (against HPV types 6, 11, 16, 18)]

Gardasil®9 (HPV9)  
[Human Papillomavirus nonavalent (against HPV types 6, 11, 16, 18, 31, 33, 45, 52 and 58)]. 

All 3 vaccines protect against the 2 types of HPV that cause about 70% of cases of cervical cancer. The HPV9 vaccine protects against 5 additional types of HPV that cause about 15% to 20% of cervical cancers. The HPV4 and HPV9 vaccines also protect against 2 types of HPV that cause about 90% of cases of genital warts. 

Vaccination is recommended for girls and women between the ages of 9 and 45 years before they come in contact with HPV. The vaccine may also benefit women who are sexually active and have not yet been infected with HPV.   

In British Columbia, the HPV9 vaccine is recommended and provided free to girls in grade 6. In September 2016, the HPV9 vaccine replaced the HPV4 vaccine which was previously provided as part of the school-based immunization program. The HPV9 vaccine is also provided free to females who are 9 to 26 years of age or infected with HIV. Since September 2017, BC's publicly funded immunization program includes the HPV9 vaccine for grade 6 boys. Therefore, all grade 6 students in BC, both female and male, are offered the HPV9 vaccine series for free as part of the regular school-based immunization program. For more information please refer to the Ministry of Health announcement: B.C. extends free HPV coverage to boys.

The HPV4 vaccine is recommended and provided free to girls and young women born in 1994 to 2004 who have not received the vaccine. Girls and young women in this age group who missed getting the HPV4 vaccine can contact their health care provider to get immunized at no cost.

The HPV4 vaccine is also free for males who are at an increased risk for HPV infection. This includes males who are:
  • 9 to 26 years of age (inclusive) and have sex with men (or who are not yet sexually active but questioning their sexual orientation), are street involved, or are HIV positive.
  • 9 to 18 years of age in the care of the Ministry of Children and Family Development. 
  • In youth custody services centres. 
For more information on eligibility for free HPV vaccine, please visit ImmunizeBC.

Those who are not eligible for free HPV vaccine can purchase it at most pharmacies, travel clinics, and some sexual health clinics. 

Vaccination prevents HPV infection but does not get rid of it once the infection occurs. Individuals who have received the HPV vaccine still require cervical cancer screening. The vaccine does not protect against all types of HPV that can cause cancer and it also does not prevent other sexually transmitted infections.

Vaccination is safe, very effective, and has few side effects. For more information, please call your local Public Health Unit or speak to your family physician.  

References

  1. Canadian Cancer Society (http://www.cancer.ca/en/cancer-information/cancer-type/cervical/statistics/?region=on#ixzz4dJJSN4Fw new cases in 2016)  
  2. http://www.bccancer.bc.ca/about/news-stories/news/2016/british-columbia-adopts-new-cervical-cancer-screening-policy (link)
  3. Kelsey J, Whittemore AS. Epidemiology and primary prevention of cancers of the breast, endometrium and ovary: a brief overview. Ann Epidemiology 1994;4:89-95. 
  4. WHO report- http://www.who.int/mediacentre/factsheets/fs380/en/
  5. Fonseca-Mourinho et al. Smoking and Cervical Cancer. ISRN Obst and Gyne, vol 2011
  6. NCI report- https://www.cancer.gov/about-cancer/causes-prevention/risk/infectious-agents/hiv-fact-sheet.
  7. IARC working Group on the Evaluation of Carcinogenic Risk of Combined Estrogen-Progestogen Contraceptives to Humans. Vol 91: 1-528, 2007.
  8. Madeleine et al. Risk of Cervical Cancer Associated with Chlamydia trachomatis Antibodies by Histology, HPV type , and HPV Cofactors. Int J Cancer 2007; 120(3):650-655.
  9. Bellinger et al. The Role of Family History of Cancer on Cervical Cancer Screening Behavior in a Population-Based Survey of Women in the Southeastern United States.-Womens Health Issues; 2003;23(4): e197-e204.
  10. Poorolajal et al. The association between BMI and cervical cancer risk: a meta-analysis. Eur J Cancer Prev. 2016 May;25(3):232-8.

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