PREVALENCE OF HUMAN PAPILLOMAVIRUS IN CERVICAL-CANCER - A WORLDWIDE PERSPECTIVE

Background: Epidemiologic studies have shown that the association of g enital human papillomavirus (HPV) with cervical cancer is strong, inde pendent of other risk factors, and consistent in several countries. Th ere are more than 20 different cancer-associated HPV types, but little is known about their geographic variation. Purpose: Our aim was to de termine whether the association between HPV infection and cervical can cer is consistent worldwide and to investigate geographic variation in the distribution of HPV types. Methods: More than 1000 specimens from sequential patients with invasive cervical cancer were collected and stored frozen at 32 hospitals in 22 countries. Slides from all patient s were submitted for central histologic review to confirm the diagnosi s and to assess histologic characteristics. We used polymerase chain r eaction-based assays capable of detecting more than 25 different HPV t ypes. A generalized linear Poisson model was fitted to the data on vir al type and geographic region to assess geographic heterogeneity. Resu lts: HPV DNA was detected in 93% of the tumors, with no significant va riation in HPV positivity among countries, HPV 16 was present in 50% o f the specimens, HPV 18 in 14%, HPV 45 in 8%, and HPV 31 in 5%, HPV 16 was the predominant type in all countries except Indonesia, where HPV 18 was more common, There was significant geographic variation in the prevalence of some less common virus types. A clustering of HPV 45 wa s apparent in western Africa, while HPV 39 and HPV 59 were almost enti rely confined to Central and South America, In squamous cell tumors, H PV 16 predominated (51% of such specimens), but HPV 18 predominated in adenocarcinomas (56% of such tumors) and adenosquamous tumors (39% of such tumors), Conclusions: Our results confirm the role of genital HP Vs, which are transmitted sexually, as the central etiologic factor in cervical cancer worldwide. They also suggest that most genital HPVs a re associated with cancer, at least occasionally. Implication: The dem onstration that more than 20 different genital HPV types are associate d with cervical cancer has important implications for cervical cancer- prevention strategies that include the development of vaccines targete d to genital HPVs.