The relationship of human papillomaviruses to anorectal neoplasia.

This review begins with an overview of the anatomy of the anal canal, which is followed by a discussion of human papillomavirus (HPV) infections in the anogenital tract. The organization of the HPV genome and the function of the encoded proteins is discussed in relation to the oncogenic potential of these viruses. Particularly stressed are interactions with known tumor suppressor genes. Then the interaction of HPV with the host cells and some growth factors is reviewed. An important consideration is the synergy between this virus and other known carcinogenic factors. These include smoking, immunologic status, and other factors. Finally, the pathologic features of anal warts and malignant lesions are summarized with respect to their histologic findings and expression of viral subtypes.