External genital human papillomavirus infections

Using imiquimod for genital warts in female patients

Genital warts (GW) are the manifestation of infection with specific types of human papillomavirus (HPV), one of the most common sexually transmitted viral infections in the world. Genital warts can be either raised (exophytic) or flat. Exophytic genital warts are most commonly secondary to inoculation of the basal epithelium with nononcogenic HPV types 6 and 11, whereas flat warts are usually secondary to potentially oncogenic HPV types 16 and 31. Genital warts can occasionally cause irritation and discomfort, particularly during intercourse, although most cases are asymptomatic. It is the psychosocial effects of infection, such as a sense of shame, depression, and anxiety, that represent the more significant toll for most patients with GW. Current therapies for GW are mainly ablative and do not directly enhance the immune response to HPV. Therefore, recurrence is a problem for many patients. Imiquimod 5% cream is a patient-applied therapy that directly enhances the immune response to HPV and is safe and effective for the treatment of GW. A reduction in viral load is observed following treatment. Low recurrence rates compared to other treatment modalities may be due to the stimulation of the cell-mediated immune response by imiquimod.

Human papillomaviruses and cervical cancer

Molecular and epidemiological studies conducted over the last 20 years led to the recognition of certain types of human papillomavirus (HPV) as the etiological agents of cervical cancer, a very common neoplasia, particularly in developing countries. More than 70 HPVs have been described, including both cutaneous and mucosal types. About half of the known HPVs, and an even higher number of variants, have been isolated from genital mucosas. The association of certain types primarily with normal tissues and benign lesions, as opposed to cancer-associated types, has led to the concept of low and high oncogenic risk HPVs, respectively. The latter express oncogenic proteins that interfere with cell growth control functions. As a consequence of the continuous expression of these viral genomes, chromosome instability may occur, leading to fully transformed cells. Studies indicate that persistence of high-risk HPVs may determine progression to more severe stages of cervical disease, while the majority of HPV infections are transient and do not seem to be important in cervical carcinogenesis. The risk for disease progression seems also to be associated with viral burden. Prospective epidemiological studies will contribute to the knowledge of the natural history of HPV infections and provide information on the determinants of viral persistence. Data derived from these studies may define the clinical utility of HPV testing and its use in cervical cancer prevention programs.