Page 13 - Screening for Cervical Cancer: Systematic Evidence Review

Chapter I. Introduction

Epidemiology

Risk Factors

Squamous cell carcinoma of the cervix and its cytologic precursors are conditions of

sexually active women. Infection with high-risk strains of HPV, generally acquired sexually, is

the most important risk factor for cervical cancer. The role of HPV is described in greater detail

below.

Risk factors relating to sexual behavior that are associated with increased risk include

onset of intercourse at an early age and a greater number of lifetime sexual partners. These

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behavioral risks appear to persist even after controlling for effects of HPV infection. A higher

number of lifetime sexual partners in the male partners of cervical cancer cases compared to

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controls has also been noted in case-control studies. Occupations are related to cervical cancer

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only through relationships with sexual behavior. Cigarette smoking is the only nonsexual
behavior consistently and strongly correlated with cervical dysplasia and cancer, independently

increasing risk two- to fourfold. 9-11 In the United States, black race and low socioeconomic

status are associated with increased risk. Recently, attention has been drawn to a positive family

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history as a plausible risk factor.

Role of Human Papilloma Virus

HPV plays a central role in the development of cervical cancer. Using modern HPV

detection methods, 95% to 100% of squamous cell cervical cancer and 75% to 95% of high-

grade CIN lesions have detectable HPV DNA. 13-15

HPV is a double-stranded DNA virus. The virus is transmitted to the cervix and vaginal

tissues primarily by sexual intercourse. 16,17 HPV can infect and persist in vulvar, vaginal, and

cervical tissue throughout a lifetime. This family of viruses includes those responsible for

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