Distribution of human papillomavirus types in cervical cancers in Hong Kong: current situation and changes over the last decades.

Human papillomavirus (HPV) type distribution among cervical cancers and its possible changes over time are key issues that determine the cost-effectiveness of HPV vaccines. Cervical cancers diagnosed during 3 periods (1997-2007, N = 280; 1984-1986, N = 74; 1972-1973, N = 81) in Hong Kong were examined for HPV type distribution using sensitive broad-catching methods. The results showed a variation in HPV distribution between histological groups. Among cervical squamous cell carcinoma (SCC) cases diagnosed over the past 10 years, HPV16 was most commonly found (61.2%), followed by HPV18 (17.7%), HPV52 (14.7%) and HPV58 (9.9%), whereas adeno/adenosquamous cell carcinoma was dominated by HPV18 (56.3%) and HPV16 (50.0%). The proportion of HPV16-positive SCC showed a significant linear trend of increase with time (45.2% for 1972-1973, 58.8% for 1984-1986, 61.2% for 1997-2007; p(Trend) = 0.023), whereas HPV52-positive SCC decreased with time (30.1% for 1972-1973; 29.4% for 1984-1986, 14.7% for 1997-2007; p(Trend) = 0.001). Vaccines comprising HPV16/18 cover 62.6% of SCC and 93.8% of adeno/adenosquamous carcinoma in Hong Kong, and inclusion of HPV52 and HPV58 can increase the coverage by 18.4% for SCC and 4.1% for adeno/adenosquamous cell carcinoma. HPV type distribution may change over time. Further investigations to reveal the determinants for such changes and continuous monitoring for possible type replacement as a result of widespread long-term use of HPV vaccines are warranted. Multiple infections are commonly revealed by sensitive broad-catching methods such as those used in this study. However, their implication on vaccine efficacy and cost-effective analyses should be taken cautiously.