Annual disease burden due to human papillomavirus (HPV) 6 and 11 infections in Finland

Abstract

In addition to cancer of the lower female genital tract, human papillomaviruses (HPV) are associated with a large number of benign, precancer and cancer lesions at different anatomic sites in both genders. Malignant tumours and their precursors are usually attributed to the oncogenic (high-risk, HR) HPV types, whereas benign lesions (papillomas) are associated with the low-risk (LR) HPV types, most notably with HPV6 and HPV11. Until recently, the main interest in HPV research has been focused on HR-HPV types and their associated pathology, and much less attention has been paid to the lesions caused by the LR-HPV types. With the recent licensing of an effective prophylactic vaccine against the 2 most important LR-HPV types (HPV6 and HPV11), it has become timely to make a systematic survey on the annual disease burden due to these 2 HPV genotypes in our country. These types of data should form the foundation for all calculations of the annual costs needed to treat these diseases by conventional means. Accurate estimates of disease burden are also mandatory for all modelling of the cost-effectiveness of prophylactic HPV6 and HPV11 vaccines. If proven useful for any of these purposes, this document will have fulfilled its purpose. In the first step, published HPV literature was used to create a list of benign, premalignant and malignant lesions associated with this virus at different anatomic sites. GLOBOCAN 2004 (IARC) database was used to derive the global numbers of incident cases for each of these malignancies in 2002, and the Finnish Cancer Registry (FCR) website for obtaining these (y 2005) numbers in Finland. The evidence linking HPV to each individual tumour category was classified as: 1) established, 2) emerging, and 3) controversial. All published evidence was weighted for each individual malignant, premalignant and benign lesion, anatomic region by region, while assessing the attributable fraction of HPV6/11 genotypes in each lesion. Because benign and most of the precancer lesions are not registered by FCR or GLOBOCAN, different approaches had to be used to derive the best estimates for their incidence, based on published literature or other registries (e.g. genital wart registry of the UK and Wales, and mass screening registry of FCR). With a lack of reasonable consensus, a lower and an upper limit was set for the range of estimates. In cases with different age-specific incidence (e.g. genital warts), the population pyramid of Finland was used to calculate the incident cases. Where well established, the different incidence rates among males and females were used to calculate the numbers of incident cases by gender. The malignant neoplasms with established or emerging evidence on the causal role of HPV are listed by their ICD-10 codes in Table I. Included in this list are also 2 controversial malignancies (colorectal cancer and endometrial cancer), of which the contradictory HPV data are critically discussed. The third major cancer in this same category (prostate cancer) was not included in the list, beca...

Prophylactic HPV vaccines: the Finnish perspective

“…Similarly, between 7859 and 8316 new cases of HPV-16/18-associated clinical lesions are detected each year in Finland [51], translating to respective age-adjusted incidence rates of 137 per 100,000 and 145 per 100,000. Aside from this difference in magnitude, another major difference between HPV-6/11 and HPV-16/18 is that the disease burden due to the former is much more evenly distributed among the genders [50], in contrast to the HPV-16/18 disease burden, of which the major proportion is contributed by females [51]. Noteworthy is the fact that the clinical lesions counted in these two reports only represent a small minority of the total viral burden due to infections by these four HPV genotypes.…”

“…According to these data, the total annual disease burden due to HPV-6/11 in this country would be between 12,666 and 13,066 new cases, covering all HPV-6/11-related pathology, corresponding to age-adjusted incidence rates of 221 per 100,000 and 228 per 100,000 [50]. Similarly, between 7859 and 8316 new cases of HPV-16/18-associated clinical lesions are detected each year in Finland [51], translating to respective age-adjusted incidence rates of 137 per 100,000 and 145 per 100,000.…”

“…This is because the vast majority of all HPV infections are transient and spontaneously resolve within a few months, without ever developing into clinical disease. However, this spontaneous clearance does not make these latent infections less important, because as long as the virus reservoir exists it serves as a potential source of viral transmission to susceptible individuals, with a multitude of HPV-6/11/16/18-associated pathologies as a potential outcome [50,51].…”

“…Until now, no systematic data on the total and/or genotype specific disease burden were available. Prompted by this obvious gap in our knowledge, this author recently completed such systematic surveys separately for the HPV-6/11 [50] and for the HPV-16/18 [51] disease burdens in Finland.…”

“…Accordingly, there cannot be any doubt that HPV infections in general represent a major public-health burden [1,2,52]. In fact, Finland is the first country where a systematic information about the annual disease burden was provided specifically for those four HPV types (HPV-6/11/16/18) covered by these two vaccines [50,51]. It is hard to deny that any disease with annual age-adjusted incidence rates exceeding 140 per 100,000 (HPV-16/18) and 220 per 100,000 (HPV-6/11) would not represent a major public-health burden [50,51].…”