Irregular squamous epithelial cells with nuclear enlargement and perinuclear halos extending from the basal layer of the squamocolumnar junction is descriptive of koilocytes that occur as a result of infection by human papillomavirus (HPV). Most HPV infections are asymptomatic and resolve spontaneously. Some infections can persist and result in warts or precancerous lesions. Cervical cancer is almost always diagnosed in addition to HPV infection. HPV types 16 and 18 currently cause nearly 70% of cervical cancer cases, and both preventative vaccines that are currently in use protect against these types. Cervical cancers are most often squamous cell carcinomas and arise from disordered epithelial growth, classified as cervical intraepithelial neoplasia 1, 2, or 3, depending on the extent of epithelial involvement. Pap smears have reduced the mortality of these cancers because they identify the precursor dysplastic lesions before the tissues become identifiably cancerous.
Risk factors for developing cervical cancer include early sexual activity, multiple sex partners, smoking, and low socioeconomic status.
Nulliparity is a risk factor for breast cancer and endometrial cancer. Cervical cancer is not sensitive to estrogen and thus nulliparity has no impact on cervical cancer. Early menarche is a risk factor for endometrial cancer and has no impact on cervical cancer. Genital warts are caused by types of HPV that are not carcinogenic. Family history is a risk factor for many cancers with a genetic factor. The primary cause of cervical cancer is HPV, thus having a family history imparts little or no additional risk.