The duration of protection conferred by prophylactic human papillomavirus (HPV) L1 virus-like particle vaccines is a critical determinant of their public health impact. A feature of vaccines that confer long-term immunity is their ability to induce immune memory.
We evaluated antibody responses against HPV types 6, 11, 16 and 18 following administration of the quadrivalent HPV-6/11/16/18 vaccine to women who had previously received a monovalent HPV-16 vaccine.
As part of an extended follow-up study conducted between 2006 and 2009 in Seattle, Washington, we administered the quadrivalent HPV-6/11/16/18 vaccine to 52 women (19 vaccine and 33 placebo recipients) who had participated in a monovalent HPV-16 vaccine trial 8.5 years earlier. Serum samples were tested for anti-HPV antibodies using competitive Luminex immunoassay.
Following administration of the first dose of the quadrivalent HPV-6/11/16/18 vaccine, the anti-HPV-16 geometric mean titer among monovalent HPV-16 vaccine recipients (GMT = 5024.0 milli-Merck units per milliliter [mMU/mL]; 95% confidence interval [CI]: 2710.1, 9313.6 mMU/mL) substantially exceeded that among the placebo recipients (GMT = 136.1; 95% CI: 78.5, 235.8 mMU/mL; p < 0.01) and their own highest anti-HPV-16 response observed during the original trial (GMT at month 7 of the original trial = 1552.7 mMU/mL; 95% CI: 1072.6, 2247.7 mMU/mL; p < 0.01).
The findings suggest that the administration of the three-dose regimen of the monovalent HPV-16 vaccine had produced memory lymphocytes, characterized by a heightened immune response following administration of the quadrivalent HPV-6/11/16/18 vaccine that effectively served as an antigen challenge.
Human papillomavirus type 16; Vaccines; Immune memory
Increasing duration of hormonal contraceptive (HC) use may be positively associated with risk of invasive cervical cancer.
This is a secondary analysis from the HPV Sentinel Surveillance Study. We examined the association between type-specific human papillomavirus (HPV) detection and current HC use among 7718 women attending 26 sexually transmitted diseases, family planning, and primary care clinics in the U.S.
There was an association between HC use and HPV-16 detection [adjusted prevalence rate ratio 1.34; (95%CI: 1.05–1.71) for oral contraceptive users and 1.41; (1.01–2.04) for depo-medroxyprogesterone acetate users]; there was no association between HC use and detection of other HPV types or any HPV overall.
Longitudinal studies are needed to better define this type-specific association and its clinical significance.
Hormonal contraception; HPV; human Papillomavirus; Papanicolaou smear
The role of circumcision in male HPV acquisition is not clear.
Male university students (18–20 years of age) were recruited from 2003–2009 and followed tri-annually. Shaft/scrotum, glans, and urine samples were tested for 37 alpha HPV genotypes. Cox proportional hazards methods were used to evaluate the association between circumcision and HPV acquisition. Logistic regression was used to assess whether number of genital sites infected at incident HPV detection or site of incident detection varied by circumcision status.
In 477 men, rates of acquiring clinically-relevant HPV types (high-risk types plus types 6 and 11) did not differ significantly by circumcision status (hazard ratio [HR] for uncircumcised relative to circumcised subjects: 0.9[95%CI:0.7–1.2]). However, compared to circumcised men, uncircumcised men were 10.1 (95%CI:2.9–35.6) times more likely to have the same HPV type detected in all 3 genital specimens than in a single genital specimen and were 2.7 (95%CI:1.6–4.5) times more likely to have an HPV-positive urine or glans specimen at first detection.
While the likelihood of HPV acquisition did not differ by circumcision status, uncircumcised men were more likely than circumcised men to have infections detected at multiple genital sites, which may have implications for HPV transmission.
HPV; human papilloma virus; circumcision; epidemiology; risk factors
Background. Although the prevalence of human papillomavirus (HPV) genital infection is similarly high in males and females, seroprevalence is lower in males. This study assessed rates and determinants of seroconversion after detection of genital HPV infection in young men.
Methods. We investigated HPV type-specific seroconversion in a cohort of heterosexual male university students who had an α9 HPV type (HPV-16, -31, -33, -35, -52, -58, or -67) detected in the genital tract (n = 156). HPV DNA and antibodies were detected and typed using liquid bead-based multiplex assays. We calculated seroconversion using Kaplan–Meier survival analysis. Cox proportional hazards models with generalized estimating equations were used to examine associations with seroconversion.
Results. Within 24 months of detecting genital HPV infection, type-specific seroconversion ranged from 4% for HPV–52 to 36% for HPV-31. HPV-16 seroconversion at 24 months was 13% (95% confidence interval [CI], 7%–25%). Among incident HPV infections, ever cigarette smoking and infection site(s) (shaft/scrotum and glans/urine vs shaft/scrotum or glans/urine only) were positively associated with type-specific seroconversion.
Conclusions. For each of the α9 HPV types, type-specific seroconversion within 24 months was observed in 36% or less of infected men. Seroconversion might be related to cigarette smoking and genital site(s) infected.
We sought to determine whether oral fluid can be used to assess serum human papillomavirus (HPV) antibody status by enrolling women who had received a prophylactic HPV-16 vaccine in a new follow-up study. After the prophylactic HPV-6/11/16/18 vaccine was licensed in the United States, we administered it to consenting participants. The sensitivity of oral fluid, treating serology as the gold standard, before and after administration of the quadrivalent vaccine was 49.6% (95% confidence interval [CI]: 42.0%–57.3%) and 100% (95% CI: 92.0%–100%), respectively. Oral fluid may have the potential to be used for monitoring of prophylactic HPV vaccines in the future.
Human papillomavirus; Prophylactic vaccines; Antibodies; Oral fluid
Background. Viral load may influence the course of human papillomavirus type 16 (HPV-16) infection.
Methods. This case-control study was nested within the 2-year Atypical Squamous Cells of Undetermined Significance and Low-Grade Squamous Intraepithelial Lesion Triage Study, in which women were followed semiannually for HPV and cervical intraepithelial neoplasia (CIN). Case patients (n = 62) were women diagnosed with CIN3 following HPV-16–positive detection at a follow-up visit. HPV-16–positive controls (n = 152) without CIN2 or CIN3 were matched to cases based on the follow-up visit in which viral load was measured. Real-time polymerase chain reaction was used for HPV-16 DNA quantification.
Results. The risk of CIN3 increased with increasing HPV-16 DNA load at the follow-up visit (odds ratio, 1.63; 95% confidence interval, 1.33–1.99 per 1 log10 unit increase); the association was not affected by whether HPV-16 was present at enrollment. When HPV-16 was present at both enrollment and follow-up, viral load remained high among cases (P = .77) but decreased substantially among controls (P = .004). Among women with HPV-16 found initially during follow-up, viral load in the first HPV-16–positive sample was associated with short-term persistence; load was higher in those with infection, compared with those without infection, 1 visit after the initial positivity (P = .001).
Conclusions. Viral load of newly detected infections and changes in viral load predict persistence and progression of HPV-16 infections.
We described prevalence estimates of high-risk human papillomavirus (HR-HPV), HPV types 16 and 18, and abnormal Papanicolaou (Pap) smear tests among American Indian/Alaska Native (AI/AN) women compared with women of other races/ethnicities.
A total of 9,706 women presenting for cervical screening in a sentinel network of 26 clinics (sexually transmitted disease, family planning, and primary care) received Pap smears and HR-HPV type-specific testing. We compared characteristics of 291 women self-identified as AI/AN with other racial/ethnic minority groups.
In our population, AI/AN and non-Hispanic white (NHW) women had similar age- and clinic-adjusted prevalences of HR-HPV (29.1%, 95% confidence interval [CI] 23.9, 34.3 for AI/AN women vs. 25.8%, 95% CI 24.4, 27.2 for NHW women), HPV 16 and 18 (6.7%, 95% CI 3.9, 9.6 for AI/AN women vs. 8.8%, 95% CI 7.9, 9.7 for NHW women), and abnormal Pap smear test results (16%, 95% CI 11.7, 20.3 for AI/AN women vs. 14.9%, 95% CI 13.7, 16.0 for NHW women). AI/AN women had a higher prevalence of HR-HPV than Hispanic women, and a similar prevalence of HPV 16 and 18 as compared with Hispanic and African American women.
We could not demonstrate differences in the prevalence of HR-HPV, HPV 16 and 18, or abnormal Pap smear test results between AI/AN and NHW women. This finding should improve confidence in the benefit of HPV vaccine and Pap smear screening in the AI/AN population as an effective strategy to reduce rates of cervical cancer.
Characterizing short-term detection patterns of young women’s incident alpha-genus human papillomavirus (HPV) infections may further understanding of HPV transmission.
Between 2000–2007, we followed 18–22 year old female university students with triannual HPV DNA and Papanicolau testing. Using Kaplan-Meier methods, we estimated: duration of detectable, type-specific incident infections; time to re-detection (among infections that became undetectable); and time to cervical lesion development after incident infection. We evaluated risk factors for short-term persistent versus transient infection with logistic regression.
303 incident type-specific infections were detected in 85 sexually active women. Median time to first negative test after incident infection was 9.4 (95%CI:7.8–11.2) months; 90.6% of infections became undetectable within two years. 19.4% of infections that became undetectable were re-detected within one year. Cervical lesions were common, and 60% were positive for multiple HPV types in concurrent cervical swabs. Incident HPV detection in the cervix only (versus the vulva/vagina only or both sites) was associated with short-term transience.
While most incident infections became undetectable within two years, re-detection was not uncommon. Cervical lesions were a common early manifestation of HPV infection.
It remains unclear whether potentially modifiable risk factors can be identified to reduce infection duration (and transmission likelihood).
human papillomavirus; incidence; duration; persistence; women; epidemiology
Prospective studies of the persistence of human papilloma-virus (HPV) variants are rare and typically small. We sequenced HPV-16 variants in longitudinal pairs of specimens from 86 women enrolled in the ASCUS-LSIL Triage Study. A change of variants was identified in 4 women (4.7% [95% confidence interval, 1.3%-11.5%]). Among women with intervening HPV results (n = 60), a variant switch occurred in 2 of 11 who had evidence of intervening negativity for HPV-16, compared with 1 of 49 who consistently tested positive (P = .11). These results suggest the possibility that rare misclassification of transient infections as persistent infections occurs in natural history studies of type-specific HPV infections.
The clinical relevance of human papillomavirus type 16 (HPV16) DNA methylation has not been well documented, although its role in modulation of viral transcription is recognized.
Study subjects were 211 women attending Planned Parenthood clinics in Western Washington for routine Papanicolaou screening who were HPV16 positive at the screening and/or subsequent colposcopy visit. Methylation of 11 CpG dinucleotides in the 3′ end of the long control region of the HPV16 genome was examined by sequencing the cloned polymerase chain reaction products. The association between risk of CIN2/3 and degree of CpG methylation was estimated using a logistic regression model.
CIN2/3 was histologically confirmed in 94 (44.5%) of 211 HPV16 positive women. The likelihood of being diagnosed as CIN2/3 increased significantly with decreasing numbers of methylated CpGs (meCpGs) in the 3′ end of the long control region (Pfor trend = 0.003). After adjusting for HPV16 variants, number of HPV16-positive visits, current smoking status and lifetime number of male sex partners, the odds ratio for the association of CIN2/3 with ≥4 meCpGs was 0.31 (95% confidence interval, 0.12–0.79). The proportion of ≥4 meCpGs decreased appreciably as the severity of the cervical lesion increased (Pfor trend = 0.001). The inverse association remained similar when CIN3 was used as the clinical endpoint. Although not statistically significant, the ≥4 meCpGs-related risk reduction was more substantial among current, as compared to noncurrent, smokers.
Results suggest that degree of the viral genome methylation is related to the outcome of an HPV16 cervical infection.
Estimate the accuracy and cost-effectiveness of cervical cancer screening strategies based on high-risk HPV DNA testing of self-collected vaginal samples.
Materials and Methods
A subset of 1,665 women (18-50 years of age) participating in a cervical cancer screening study were screened by liquid-based cytology and by high-risk HPV DNA testing of both self-collected vaginal swab samples and clinician-collected cervical samples. Women with positive/abnormal screening test results and a subset of women with negative screening test results were triaged to colposcopy. Based on individual and combined test results, five screening strategies were defined. Estimates of sensitivity and specificity for cervical intraepithelial neoplasia grade 2 or worse were calculated and a Markov model was used to estimate the incremental cost-effectiveness ratios (ICERs) for each strategy.
Compared to cytology-based screening, high-risk HPV DNA testing of self-collected vaginal samples was more sensitive (68%, 95%CI=58%-78% versus 85%, 95%CI=76%-94%) but less specific (89%, 95%CI=86%-91% versus 73%, 95%CI=67%-79%). A strategy of high-risk HPV DNA testing of self-collected vaginal samples followed by cytology triage of HPV positive women, was comparably sensitive (75%, 95%CI=64%-86%) and specific (88%, 95%CI=85%-92%) to cytology-based screening. In-home self-collection for high-risk HPV DNA detection followed by in-clinic cytology triage had a slightly lower lifetime cost and a slightly higher quality-adjusted life expectancy than did cytology-based screening (ICER of triennial screening compared to no screening was $9,871/QALY and $12,878/QALY, respectively).
Triennial screening by high-risk HPV DNA testing of in-home, self-collected vaginal samples followed by in-clinic cytology triage was cost-effective.
cervical cancer; screening; hpv; self-collect; cost-effectiveness
Little is known about detection of genital human papillomavirus (HPV) types in women’s fingertips. The study objectives were to determine the presence of genital HPV types in fingertip samples and agreement between fingertip and genital samples for detecting HPV.
At tri-annual visits, genital and fingertip samples were collected from female university students and tested for 37 HPV genotypes by PCR-based assay. Type-specific concordance between paired fingertip and genital samples was evaluated using a kappa statistic for percent positive agreement (“kappa +”). Paired samples with type-specific concordant fingertip and genital results were selected for variant characterization.
A total of 357 fingertip samples were collected from 128 women. HPV prevalence in fingertip samples was 14.3%. Although percent positive agreement between fingertips and genitals for detecting type-specific HPV was low (17.8%; kappa+=0.17, 95%CI:0.10–0.25), 60.4% of type-specific HPV detected in the fingertips was detected in a concurrent genital sample. All but one of 28 paired concordant samples were positive for the same type-specific variant in the fingertip and genital sample. Re-detection of HPV types at the subsequent visit was more common in genital samples (73.3%) than in fingertip samples (14.5%) (p<.001).
Detection of genital HPV types in the fingertips was not uncommon. While impossible to distinguish between deposition of DNA from the genitals to the fingertips and true fingertip infection, the rarity of repeat detection in the fingertips suggests that deposition is more common.
Finger-genital transmission is plausible, but unlikely to be a significant source of genital HPV infection.
human papillomavirus; fingertip; genital; women; epidemiology
High-risk human papillomavirus (hrHPV) is the primary cause of cervical cancer. As Chlamydia trachomatis is also linked to cervical cancer, its role as a potential co-factor in the development of cervical intraepithelial neoplasia (CIN) grade 2 or higher was examined.
The placebo arms of two large, multinational, clinical trials of an HPV6/11/16/18 vaccine were combined. A total of 8441 healthy women aged 15–26 years underwent cervicovaginal cytology (Papanicolaou (Pap) testing) sampling and C trachomatis testing at day 1 and every 12 months thereafter for up to 4 years. Protocol-specified guidelines were used to triage participants with Pap abnormalities to colposcopy and definitive therapy. The main outcome measured was CIN.
At baseline, 2629 (31.1%) tested positive for hrHPV DNA and 354 (4.2%) tested positive for C trachomatis. Among those with HPV16/18 infection (n=965; 11.4%) or without HPV16/18 infection (n=7382, 87.5%), the hazard ratios (HRs) associated with development of any CIN grade 2 according to baseline C trachomatis status were 1.82 (95% CI: 1.06 to 3.14) and 1.74 (95% CI 1.05 to 2.90), respectively. The results were comparable when only the 12 most common hrHPV infections were considered, but the excess risk disappeared when the outcome was expanded to include CIN grade 3 or worse.
Further studies based on larger cohorts with longitudinal follow-up in relation to the C trachomatis acquisition and a thorough evaluation of temporal relationships of infections with hrHPV types, C trachomatis and cervical neoplasia are needed to demonstrate whether and how in some situations C trachomatis sets the stage for cervical carcinogenesis.
NCT00092521 and NCT00092534.
We determined the feasibility of human papillomavirus (HPV) detection in cervical exfoliated cells collected as dry swab samples. Both dry cervical swab and specimen transport medium (STM) cervical swab samples were collected from 135 patients attending either colposcopy or women's clinics in Guayaquil, Ecuador, who had a cytology diagnosis within 6 months. HPV was detected by dot blot hybridization and genotyped by the liquid bead microarray assay (LBMA). Overall, 23.1% of dry samples were positive for any high-risk HPV types, and 24.6% of STM samples were positive for any high-risk HPV types. Of 125 paired samples, the type-specific high-risk HPV proportion positive agreement was 60.7% (kappa, 0.69; 95% confidence interval [CI], 0.53 to 0.82). Of six women with cytological evidence of invasive cervical cancer, high-risk HPV DNA was detected in three of their STM samples and in five of their dry samples. Dry samples were more likely to be insufficient for HPV testing than STM samples. Consistent with this observation, the amount of genomic DNA quantitated with the β-actin gene was almost 20 times lower in dry samples than in STM samples when detected by the real-time TaqMan assay; however, HPV DNA viral loads in dry samples were only 1.6 times lower than those in matched STM samples. We concluded that exfoliated cervical cells could be collected as dry swab samples for HPV detection.
Studies of viral load-related persistence of human papillomavirus (HPV) infection are rare, with inconsistent results reported.
Study subjects were 741 and 289 women who were positive for HPV16 and HPV18, respectively, at enrollment into in the ASCUS-LSIL Triage Study and who returned one or more times for HPV testing during a biannual 2-year follow-up. Baseline HPV16 and HPV18 copies per nanogram of cellular DNA were measured by real-time polymerase chain reaction.
Women with, compared to without, persistent infection at month 6 had higher viral load at enrollment (P<0.001 for HPV16; P=0.01 for HPV18). The association of per 1 log10-unit increase in viral load with the first 6-month persistence of HPV16 or HPV18 was statistically significant among women with multiple types at enrollment (OR=1.53, 95% CI, 1.29–1.82 for HPV16; OR=1.35, 95% CI, 1.09–1.68 for HPV18) but not among those with mono-type infections (test for interaction between viral load and coinfection: P=0.002 for HPV16; P=0.34 for HPV18). Among women who continued to be positive at month 6, 12, or 18, persisting for another 6 months was unrelated to baseline viral load.
Higher viral load of prevalent HPV16 or HPV18 infection was associated with short- but not long-term persistence.
Human Papillomavirus; Viral Load; Persistence
Although cigarette smoking has been associated with increased human papillomavirus (HPV) detection, its impact on HPV DNA load is unknown.
Study subjects were women who were positive for HPV16 and/or HPV18 at enrollment into the ASCUS-LSIL Triage Study. Assessments of exposure to smoke and sexual behavior were based on self-report. Viral genome copies per nanogram of cellular DNA were measured by multiplex real-time polymerase chain reaction. Linear or logistic regression models were used to assess the relationship between cigarette smoking and baseline viral load.
Of 1,050 women (752 with HPV16, 258 with HPV18, and 40 with both HPV16 and HPV18), 452 (43.0%) were current smokers and 101 (9.6%) were former smokers at enrollment. Baseline viral load was statistically significantly greater for current, compared to never, smokers (P = 0.03 for HPV16; P = 0.02 for HPV18), but not for former smokers. Among current smokers, neither HPV16 nor HPV18 DNA load appeared to vary appreciably by age of smoking initiation, smoking intensity or smoking duration. Results remained similar, when the analysis of smoking-related HPV16 DNA load was restricted to women without detectable cervical abnormality.
Higher baseline HPV16 and HPV18 DNA load was associated with status as a current but not former smoker. A lack of dose-response relationship between cigarette smoking and viral load may indicate a low threshold for the effect of smoking on HPV DNA load.
Human Papillomavirus; Viral Load; cigarette smoking
We conducted an extended follow-up study (March 2006 – May 2008) to assess the longer-term efficacy of a prophylactic monovalent human papillomavirus (HPV) type 16 L1 virus-like particle vaccine in women (n = 290) who had enrolled in a randomized controlled trial of this vaccine during October 1998 – November 1999 in Seattle and remained HPV-16 DNA negative during the course of that trial. During the extended follow-up period, none of the vaccine recipients was found to be infected with HPV-16 or developed HPV-16-related cervical lesions; among placebo recipients, 6 women were found to be infected with HPV-16 (vaccine efficacy [VE] = 100%; 95% confidence interval [CI]: 29% – 100%) and 3 women developed HPV-16-related cervical lesions (VE = 100%; 95% CI: <0% – 100%). Approximately 86% of vaccine recipients remained HPV-16 competitive Luminex immunoassay seropositive at an average of 8.5 years of follow-up. During the combined original trial and extended follow-up period, 20 and 22 women developed any cervical lesion regardless of HPV type among the vaccine and placebo recipients, respectively (VE = 15%; 95% CI: <0% – 56%). The results suggest that this monovalent HPV-16 vaccine remains efficacious through 8.5 years after its administration.
Human papillomavirus type 16; Prophylactic vaccines; Efficacy
The impact of loop electrosurgical excision procedure (LEEP) treatment for cervical precancerous lesions on subsequent acquisition of new human papillomavirus (HPV) infections is not well described.
Cumulative incidence rate ratios (IRR) for treated versus untreated women at 6- and 24-months of follow-up with 95% confidence intervals (95%CI) were calculated for infection by individual HPV genotypes, any HPV genotype, any carcinogenic HPV genotype, any non-carcinogenic HPV genotypes, and phylogenetic groups of HPV genotypes were compared between HPV-positive women who underwent colposcopy and were treated by LEEP (n = 195) and were untreated (n = 1,625) at entry into a two-year study.
Treated women were 29% less likely than untreated women to acquire carcinogenic HPV genotypes at the 6-month follow-up (IRR = 0.71; 95%CI = 0.50–1.00) and 18% less likely at the 24-month follow-up (IRR = 0.82, 95%CI = 0.68–1.01). Treated women were, respectively, 56% and 40% less likely to acquire HPV genotypes of the α9 phylogenetic species (which includes HPV16) at 6-months (IRR = 0.44, 95%CI = 0.23–0.85) and 24-months (IRR = 0.60, 95%CI = 0.42–0.85).
LEEP may reduce the acquisition of certain carcinogenic HPV genotypes related to HPV16.
human papillomavirus (HPV); loop electrosurgical excision procedure (LEEP); cervical intraepithelial neoplasia (CIN); cervical cancer; atypical squamous cell of undetermined significance (ASCUS); low-grade squamous intraepithelial lesion (LSIL)
To quantify the risk of human papillomavirus (HPV) acquisition associated with a first male sex partner and to identify associated risk factors, we analyzed data from women who were enrolled before or within 3 months of first intercourse with a male partner and were censored at the report of a second partner. The 1-year cumulative incidence of first HPV infection was 28.5% (95% confidence interval, 20.6%–38.6%) and increased to almost 50% by 3 years. The risk was increased when the first male partner was sexually experienced. Our results indicate a high risk of HPV infection in young women who have had just 1 male sex partner.
Examine the relationship of depot-medroxyprogesterone acetate (DMPA) and combined oral contraceptive (COC) use with cervical intraepithelial neoplasia (CIN).
Two case-control studies of women who presented for gynecological care and underwent cytologic and human papillomavirus (HPV) testing were performed. The first included oncogenic HPV-positive women grouped based on histology: negative(n=152), CIN1(n=133), and ≥CIN2-3(n=173). For the second, two groups were identified: negative HPV/negative histology(n=107) and positive oncogenic HPV/negative histology(n=152).
Among oncogenic HPV-positive women, DMPA use was inversely associated with ≥CIN2-3 (adjusted odds ratio[ORadj]=0.4;95% confidence interval[CI]=0.2–1.1) and CIN1 (ORadj=0.1;95% CI=0.01–0.6); COC use was not associated with either. Among histologically negative women, DMPA use was associated with oncogenic HPV (ORadj=4.7;95% CI=1.4–15.8).
Among women with oncogenic HPV, hormonal contraceptive use was not associated with an increased risk of ≥CIN2-3. Longer-term DMPA use may attenuate the colposcopic and histologic features of CIN as women reporting such use were more likely than others to have cervical oncogenic HPV without evidence of CIN.
CIN; hormonal contraception; DMPA; Oncogenic HPV infection
Given the established links between young age at first intercourse (AFI), number of sex partners, high-risk human papillomavirus infection, and squamous cell cervical cancer (SCC), we hypothesized that women diagnosed with SCC at younger ages would be more likely to report young AFI than women diagnosed later in life.
We performed a population-based investigation among invasive SCC cases who were diagnosed between 1986 and 2004, were 22 to 53 years old, and lived in the metropolitan Seattle-Puget Sound region (n=333). Using multivariate linear regression, we estimated coefficients and 95% confidence intervals (CI) to assess the association between age at SCC diagnosis and AFI (<15, 15–18, ≥19) and number of sex partners before age 20 (0, 1, 2–4, 5–14, 15+), accounting for birth year and other factors. Interactions were assessed using the likelihood ratio test.
The interval between AFI and SCC diagnosis ranged from 4 to 35 years. In a multivariate model, compared to SCC cases reporting AFI≥19, the mean age of diagnosis was 3.1 years younger for SCC cases reporting AFI<15 (CI: −5.8, −0.5) and 2.6 years younger for SCC cases reporting AFI 15–18 years (CI: −4.6, −0.6). Although number of sex partners before age 20 was associated with age at SCC diagnosis in a crude analysis, the association was not independent of AFI. However, in the AFI≥19 and AFI<15 groups, differences in effect were seen by number of sex partners before age 20 (p for interaction=0.08), with the association remaining strong and significant only in the AFI<15 group that had 2 or more partners before age 20 (coefficient: −4.2, CI: −6.3, −2.1).
Among younger and middle-aged women with SCC, early age of diagnosis was associated with early AFI, though the effect appeared to be modified by number of sex partners before age 20.
Cervical Carcinoma; Sexual Initiation; Age
The clinical relevance of the amount of human papillomavirus type 18 (HPV18) DNA in cervical tissue (ie, HPV18 DNA load) is unknown.
Study subjects were 303 women who were HPV18 positive at enrollment into the Atypical Squamous Cells of Undetermined Significance (ASC-US) and Low-Grade Squamous Intraepithelial Lesion (LSIL) Triage Study. HPV18 DNA load, expressed as copies of HPV18 per nanogram of cellular DNA, at enrollment was quantitatively measured. Subjects were followed up semiannually for a period of 2 years for detection of cervical intraepithelial neoplasia 2–3 (CIN2–3). A linear regression model was used to examine associations of CIN2–3 with HPV18 DNA load. All statistical tests were two-sided.
CIN2–3 was confirmed in 92 of 303 (30.4%) HPV18-positive women. Among women without CIN2–3, HPV18 DNA load was positively associated with increasing severity of cervical cytology at enrollment (Ptrend < .001). However, among those with CIN2–3, HPV18 DNA load was not associated with severity of cervical cytology at enrollment (Ptrend = .33). The ratios of geometric means of HPV18 DNA load at enrollment among women with CIN2–3, relative to those without, were 6.06 (95% confidence interval [CI] = 0.31 to 117.92) for those with normal cytology at enrollment, 0.50 (95% CI = 0.10 to 2.44) for those with ASC-US, 0.11 (95% CI = 0.03 to 0.46) for those with LSIL, and 0.07 (95% CI = 0.01 to 0.80) for those with high-grade squamous intraepithelial lesion (HSIL). After adjusting for age and coinfection with other high-risk HPVs, a statistically significant association of lower HPV18 DNA load with CIN2–3 was observed among women with LSIL or HSIL at enrollment (P = .02). Within the 2-year period, HPV18 DNA load was unrelated to the timing of CIN2–3 diagnosis. Overall results were similar when the outcome was CIN3.
HPV18 DNA load was higher for women with LSIL or HSIL at enrollment with no evidence of CIN2–3 during the 2-year follow-up period than it was for women with CIN2–3. Thus, testing for high levels of HPV18 DNA does not appear to be clinically useful.
Although correlations of cervical cytology to human papillomavirus (HPV) load and histopathology are recognized, it is largely undetermined whether viral load-related risks of cervical intraepithelial neoplasia III (CIN3) differ by cytology.
Study subjects were 821 women enrolled in the ASCUS-LSIL Triage Study who were positive for HPV16 at entry. Women were followed semi-annually over 2 years. Baseline HPV16 load was measured by real-time PCR; expressed as log10 [HPV16 copies per-nanogram of cellular DNA].
CIN3 was confirmed in 34.8% of 821 women during 2-year follow-up. The adjusted odds ratio (OR) associating 2-year cumulative risk of CIN3 with per log10–unit increase in HPV16 load was 1.46 (95%CI, 1.29-1.64). The ORs varied from 1.66 (95%CI, 1.16-2.37) for women with normal cytology at enrollment to 0.86 (95%CI, 0.61-1.20) for those with HSIL. Among women with normal cytology at enrollment, the area under the receiver operating characteristic curve for detecting CIN3 by viral load was 0.70 (95%CI, 0.61-0.78).
HPV16 DNA load was associated with CIN3 risk but the associations varied with cytology detected at the time when the viral load was measured. Clinical utility of testing for HPV16 load for CIN3 detection was minimal even in women with normal cytology.
Human Papillomavirus; Viral load; Cervical Intraepithelial Neoplasia
Given that the integration of human papillomavirus type 16 (HPV16) into the host genome occurs preferentially with the disruption of the E2 gene, a ratio of E2 to E7 gene copies is often used as a marker for integration. It is largely undetermined, however, whether ratio estimates are affected by HPV intratypic variations. We assembled four plasmid constructs, each containing a DNA fragment from an HPV16 European, Asian-American, African-1, or African-2 variant. These constructs and nine cervical swab samples were assayed by real-time PCR with two primer-probe sets for each gene: a specific set, fully complementary to the HPV16 prototype, and a degenerate set, incorporating degenerate bases at positions where nucleotides differed among the variants. The ratio of E2 to E7 gene copies for the European variant construct was close to 1, no matter which sets of primers and probes were used. While the ratios for the African-1 and Asian-American variant constructs remained close to 1 with the degenerate sets of primers and probes, the ratios were 0.36 and 2.57, respectively, with the specific sets of primers and probes. In addition, a nucleotide alteration at the position immediately following the 3′ end of the E2 forward primer binding site was found to be responsible for an underestimation of E2 gene copies for the African-2 variant construct. Similar patterns were found in nine cervical samples. In conclusion, mismatches between the primers and probes and their targets due to HPV16 intratypic variations would introduce errors in testing for integration; this situation can be sufficiently ameliorated by incorporating degenerate bases into the primers and probes.