An alert to Latin America: current human papillomavirus vaccination trends highlight key barriers to successful implementation

Abstract

Human papillomavirus (HPV)-related cancer continues to be a leading cause of cancer in Latin America, mainly due to cervical cancer burden. The prevalence of HPV infection has been found to be twice as high in Latin America compared with the worldwide average,1,2 and it is associated with 68,220 new cases of cervical cancer per year. Incidence rates range from 20 to 80 per 100,000 women, and 31,712 cervical cancer-associated deaths occur each year in Latin America.3 According to the Pan American Health Organization (PAHO), if current trends continue, the number of women with cer vical cancer in Latin America will reach over 110,000 cases annually by 2030. Because cervical cancer affects predominant ly young women, it represents the single biggest cause of years of life lost due to cancer in the developing world.4 Furthermore, without effective screening strategies, the annual numbers of other HPV-related cancers (eg, oropharyngeal and anal cancers) also are increasing.5 In high-income countries (HICs), due to the invention of the Papanicolaou (Pap) test and after its widespread imple mentation in the 1960s, the incidence of cervical cancer declined by >60%, thereby confirming this as the most effective cancer screening tool in the history of medicine. However, the Pap test has achieved limited success in low-income and middle-income countries (LMICs) worldwide, including in Latin America. This limited success is attributed to several fac tors, including a lack of organized screening programs within fragmented health systems, technical limitations, a low pop ulation coverage and not sufficiently reaching high-risk subpopulations, poor quality control, and insufficient monitoring. Timely treatment and follow-up for women with abnormal cytology results are among other difficulties en countered. The few, relatively well-organized screening programs that do exist in Latin America are primarily located in major urban centers.6 The advent of HPV prophylactic vaccination offers a promising step toward cervical cancer prevention. Based on the high incidence of HPV-related cancers, the strong carcinogenic potential of certain HPV strains, and numerous trials proving the high efficacy of HPV vaccines, prophylactic immunization is considered one of the most important available tools with which to alter the incidence of HPV-associated cancers in countries throughout Latin America and all other LMICs. Large-scale HPV immunization can reduce lives lost due to preventable cancers and relieve health systems strained by the costly treatment of these cancers, which commonly present at later stages. However, despite its proven effi cacy and safety, vaccine uptake by populations has been lower than expected for several reasons, including the high cost of the HPV vaccine, the requirement for multiple doses, limited knowledge of HPV vaccine efficacy and safety, cultural bar riers, insufficient provider recommendations, and inadequate implementation strategies.