Epidemiology and natural history of human papillomavirus infections and type-specific implications in cervical neoplasia.
ABSTRACT Worldwide human papillomavirus (HPV) prevalence in women with normal cytology at any given point in time is approximately 10% indicating that HPV is one of the most common sexually transmitted infections. HPV-16 is consistently the most common type and HPV-18 the second with some minor regional differences. Furthermore, across the spectrum of cervical lesions, HPV-16 is consistently the most common HPV type contributing to 50-55% of invasive cervical cancer cases strongly suggesting that this viral type has a biological advantage for transmission, persistency and transformation. The same phenomenon is observed albeit at a lower level for HPV-18 and HPV-45. Sexual behavioral patterns across age groups and populations are central to the description of the HPV circulation and of the risk of infection. The concept of group sexual behavior (in addition to individual sexual behavior) is important in exploring HPV transmission and has implications for defining and monitoring HPV and cancer prevention strategies. In natural history studies, the pattern of HPV DNA prevalence by age groups is similar to the patterns of HPV incidence. Rates of exposure in young women are high and often include multiple types. There is a spontaneous and rapid decrease of the HPV DNA detection rates in the middle-age groups followed by a second rise in the post-menopausal years. This article reviews: 1) the evidence in relation to the burden of HPV infections in the world and the contributions of each HPV type to the spectrum of cervical cellular changes spanning from normal cytology to invasive cervical cancer; 2) the critical role of the patterns of sexual behavior in the populations; and 3) selected aspects of the technical and methodological complexity of natural history studies of HPV and cervical neoplasia.
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ABSTRACT: BackgroundMore information is needed about time between sexual initiation and human papillomavirus (HPV) infection and development of cervical precancer.MethodsThe objectives were to investigate the time between first sexual activity and detection of first cervical HPV infection or development of first cervical intraepithelial neoplasia (CIN), and associated factors in women from the double-blind, multinational, 4-year PATRICIA trial. PATRICIA enroled women aged 15?25 years with no more than 6 lifetime sexual partners. Women were randomized 1:1 to the HPV-16/18 AS04-adjuvanted vaccine or to control, but only women from the control arm who began sexual intercourse during the study or within 6?months before enrolment, and had no HPV infection detected before the recorded date of their first sexual intercourse, were included in the present analysis. The time between onset of sexual activity and detection of the first cervical HPV infection or development of the first CIN lesion was analyzed using Kaplan-Meier and univariate and multivariable Cox proportional-hazards models.ResultsA total of 9337 women were enroled in the control arm of PATRICIA of whom 982 fulfilled the required inclusion criteria for analysis. A cumulative total of 28%, 44%, and 62% of the subjects had HPV infection within 12, 24, and 48?months, respectively. The overall incidence rate was 27.08 per 100 person-years. The most common oncogenic types associated with 6-month persistent infection were HPV-16 (incidence rate: 2.74 per 100 person-years), HPV-51 (2.70), HPV-52 (1.66), HPV-66 (1.14), and HPV-18 (1.09). Increased infection risk was associated with more lifetime sexual partners, being single, Chlamydia trachomatis history, and duration of hormone use. CIN1+ and CIN2+ lesions were most commonly associated with HPV-16, with an overall incidence rate of 1.87 and 1.07 per 100 person-years, respectively. Previous cervical HPV infection was most strongly associated with CIN development.ConclusionsMore than 25% of women were infected with HPV within 1?year of beginning sexual activity. Without underestimating the value of vaccination at older ages, our findings emphasize its importance before sexual initiation.Trial registrationclinicaltrials.gov: NCT00122681.BMC Infectious Diseases 10/2014; 14:551. · 2.56 Impact Factor
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ABSTRACT: Cervical cancer is the third most common cause of cancer in women in the world. During the past few decades tremendous strides have been made toward decreasing the incidence and mortality of cervical cancer with the implementation of various prevention and screening strategies. The causative agent linked to cervical cancer development and its precursors is the human papillomavirus (HPV). Prevention and screening measures for cervical cancer are paramount because the ability to identify and treat the illness at its premature stage often disrupts the process of neoplasia. Cervical carcinogenesis can be the result of infections from multiple high-risk HPV types that act synergistically. This imposes a level of complexity to identifying and vaccinating against the actual causative agent. Additionally, most HPV infections spontaneously clear. Therefore, screening strategies should optimally weigh the benefits and risks of screening to avoid the discovery and needless treatment of transient HPV infections. This article provides an update of the preventative and screening methods for cervical cancer, mainly HPV vaccination, screening with Pap smear cytology, and HPV testing. It also provides a discussion of the newest United States 2012 guidelines for cervical cancer screening, which changed the age to begin and end screening and lengthened the screening intervals.World journal of clinical oncology. 10/2014; 5(4):744-52.
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ABSTRACT: Despite numerous human papillomavirus (HPV) frequency studies in women with cervical cancer (CC), little is known of HPV frequency trends according to patient age. In this work, we compare the mean age and frequency distribution by age of CC patients positive for different HPVs. This study included 462 CC patients. HPVs were detected by PCR and typed using DNA sequencing. A total of 456 patients (98.7%) were positive for HPV: 418 (90.5%) had single and 38 (8.2%) had double HPV infections. HPV16 (46.5%), HPV18 (10.4%), HPV45 (6.7%), and HPV31 (4.1%) were the most frequent viral types in single-infected patients. The mean ages of single-infected patients with HPV16 (49.2±13.3), HPV18 (47.9±12.2), HPV45 (47.9±11.7), or HPV39 (42.6±8.9) were significantly lower than the mean ages of patients singly (53.9±12.7; p<0.001, t-test) or doubly (55.4±12.7; p<0.05, t-test) infected with the remaining HPVs. Three different trends were identified: one for HPV16, another for HPVs18/45/39, and a third for the rest of HPVs. The frequency trend of HPV16 shows two peaks. The first (63.2%) was found in the youngest women (≤35 years), followed by a decreasing trend until the age of 55-60 years (31.1%). The second peak arose at 61-65 years (52.5%), followed by a decreasing trend. The trend for HPVs18/45/39 declined from the youngest (19.3%) to the oldest (>70 years; 12.8%) women. In contrast, the trend for the remaining HPVs increased from the youngest (15.8%) to the oldest (46.2%) women. Unlike other life-style factors, low-risk sexual behavior was associated with late onset of CC independent of low-oncogenic HPV types (p<0.05, Wald chi-square statistic). The data indicate that most CCs in young women depend on the presence of high-oncogenic HPVs. In contrast, almost half of CCs in older patients had low-oncogenic HPVs, suggesting they could depend on the presence of other factors.PLoS ONE 10/2014; 9(10):e109406. · 3.53 Impact Factor