M. Concepcion Bratti

Epidemiologic Profile of Type-Specific Human Papillomavirus Infection and Cervical Neoplasia in Guanacaste, Costa Rica

BACKGROUND Detailed epidemiologic studies of cervical type-specific human papillomavirus (HPV) infection in large populations are scarce. METHODS We recruited a population-based cohort in Guanacaste, Costa Rica. Participants were interviewed, screened for cervical neoplasia, and tested for >40 HPV types by use of MY09/11 L1 consensus primer polymerase chain reaction. We estimated the risk factors for infection and the associations between type-specific HPV infections and cervical intraepithelial neoplasia (CIN) and cancer in 8514 sexually active women who had not undergone a hysterectomy. RESULTS The overall HPV prevalence was 26.5%. The most common type was HPV-16 (3.6% of the population). HPV prevalence showed a U-shaped age-specific curve. Sexual behaviors were the main determinants of oncogenic and nononcogenic infections; age at first sexual intercourse was not independently associated with infection. Barrier contraceptive use was somewhat protective against infection. Oncogenic infections were strongly associated with risk of all grades of CIN and of cancer. Types 16, 18, and 58 were the most common in women diagnosed with CIN3 and cancer. Except for those that included HPV-16, multiple-type infections were associated with an increased risk (compared with that for single-type infections) of all grades of CIN and of cancer. CONCLUSIONS We confirmed the bimodal age pattern of HPV infection in Guanacaste and the sexually transmitted nature of both oncogenic and nononcogenic HPV types.

A prospective study of age trends in cervical human papillomavirus acquisition and persistence in Guanacaste, Costa Rica

BACKGROUND Cross-sectional human papillomavirus (HPV) DNA prevalence peaks at young ages, reflecting sexual acquisition and typically rapid clearance. In some populations, HPV prevalence demonstrates a second peak in older women. Longitudinal data may help to explain this second peak. METHODS We followed a population-based cohort of 7237 women in Guanacaste, Costa Rica, in which we had previously observed a second peak in the baseline HPV prevalence in older women. We tested for >40 HPV types by polymerase chain reaction. We analyzed age-specific patterns of acquisition and persistence 5-7 years after enrollment for individual HPV types. RESULTS At enrollment and follow-up, cross-sectional data revealed U-shaped age-specific HPV prevalence curves for virtually every type, with higher prevalences in the younger and older women than in the middle-aged women. Prospectively, acquisition of types decreased significantly as women aged (PTrend<.05, for both), with the highest peak in young women and a secondary minor peak in older women. Type-specific persistence of HPV increased with age (PTrend<.0001). Overall, HPV acquisition predominated at younger ages, whereas persistent infections gradually became more prominent with age (PTrend<.0001). CONCLUSIONS Newly apparent infections decreased, whereas persistence increased, with age; this latter tendency supports the utility of HPV screening in older women.

Relationships of Human Papillomavirus Type, Qualitative Viral Load, and Age with Cytologic Abnormality

Persistent cervical infections with carcinogenic human papillomaviruses (HPV) cause virtually all cervical cancer. Cytologic abnormalities are the manifestations of HPV infections used to identify women at risk. To compare the potential of the full range of anogenital HPV genotypes to induce cytopathic effects, we examined the influences of HPV type, viral load, and age on cytopathology among 1,222 women having a single HPV type at enrollment into a 10,000-woman population-based study in Costa Rica. Cervical specimens were tested for approximately 40 HPV types by MY09/MY11 L1 primer PCR and type-specific dot blot hybridization. Types were organized by phylogenetic species and cancer risk. PCR signal strength served as a qualitative surrogate for viral load. Overall, 24.8% [95% confidence interval (95% CI), 22.4-27.3] of single prevalent HPV infections had concurrent abnormalities (atypical squamous cells or worse) ranging from 0.0% to 80.0% based on HPV type. Noncarcinogenic alpha3/alpha15 types, although highly prevalent, uncommonly caused cytologic abnormalities (13.1%; 95% CI, 9.8-17.0). In contrast, one quarter to nearly one half of infections with a single major carcinogenic species type (alpha9/alpha11/alpha7/alpha5/alpha6) produced abnormalities. Greater abnormalities were observed with increasing qualitative viral load of carcinogenic types; fewer abnormalities were observed among older women (>54 years). A high percentage (46.2%) of detected abnormalities in women infected with HPV16 or related alpha9 types were high grade or worse, consistent with strong carcinogenicity, compared with 10.7% in women infected with alpha7 types, including HPV18, a major cause of adenocarcinoma. The lack of evident severe abnormalities associated with HPV18 and related HPV types might have implications for screening for poorly detected glandular and alpha7-related lesions.

Cervical specimens collected in liquid buffer are suitable for both cytologic screening and ancillary human papillomavirus testing

Several new techniques have been developed to improve the sensitivity of cervical carcinoma screening and reduce equivocal cytologic diagnoses referred to as atypical squamous cells of undetermined significance (ASCUS). This study evaluates the effectiveness of combining two newly introduced diagnostic techniques: preparation of thin‐layer cytologic slides from ThinPrep liquid buffer and selected Hybrid Capture testing for human papillomavirus (HPV) DNA. Because HPV DNA detection has been strongly associated with the presence of a cervical carcinoma precursor (“squamous intraepithelial lesion,” or SIL), HPV testing might be useful for identifying women with ASCUS who have an underlying SIL.

Human leukocyte antigen class I and II alleles and risk of cervical neoplasia: results from a population-based study in Costa Rica.

To examine human leukocyte antigen (HLA) involvement in the development of all grades of cervical neoplasia, a nested case-control study of 10,077 women in Guanacaste, Costa Rica, was conducted. Participants had invasive cervical cancer, high-grade squamous intraepithelial lesions (HSILs; n=166), or low-grade squamous intraepithelial lesions (LSILs); were positive for human papillomavirus (HPV) with no evidence of cervical neoplasia (n=320); or were HPV negative with no evidence of cervical neoplasia but with a history of high-risk sexual behavior (n=173). Compared with women who were HPV negative, women with HLA-DRB1*1301 were associated with decreased risk for cancer/HSILs (odds ratio [OR], 0.4; 95% confidence interval [CI], 0.2-0.7) and for LSILs/HPV (OR, 0.6; 95% CI, 0.3-0.9). Women with both HLA-B*07 and HLA-DQB1*0302 had an 8.2-fold increased risk for cancer/HSILs (95% CI, 1.8-37.2) and a 5.3-fold increased risk for LSILs/HPV (95% CI, 1.2-23.7). These results support the hypothesis that multiple risk alleles are needed in order to increase risk for cervical neoplasia, but a single protective allele may be sufficient for protection.

p53 polymorphism and risk of cervical cancer

Storey and co-workers have reported data suggesting that individuals homozygous for arginine at residue 72 of p53 (p53Arg) are about seven times more susceptible to invasive cervical cancer than individuals who carry at least one proline at that position (p53Pro). These preliminary data were supported by in vitro evidence demonstrating that the E6 oncoprotein of human papilloma virus (HPV) degrades p53Arg more efficiently than p53Pro. We have now tested specimens from a total of 1,309 women in three studies for p53 polymorphisms. We find that p53Arg is not associated with an increased risk of preinvasive or invasive cervical neoplasia; indeed, there is a tendency for p53Arg to be associated with a decreased risk of neoplasia.

Age-Related Changes of the Cervix Influence Human Papillomavirus Type Distribution

Approximately 15 human papillomavirus (HPV) types cause virtually all cervical cancer whereas other HPV types are unrelated to cancer. We were interested in whether some noncarcinogenic types differ from carcinogenic in their affinity for the cervical transformation zone, where nearly all HPV-induced cancers occur. To examine this possibility, we tested cervical specimens from 8,374 women without cervical precancer and cancer participating in a population-based study in Guanacaste for >40 HPV types using PCR. We compared age-group specific prevalences of HPV types of the alpha9 species, which are mainly carcinogenic and include HPV16, to the genetically distinct types of the alpha3/alpha15 species (e.g., HPV71), which are noncarcinogenic and common in vaginal specimens from hysterectomized women. We related HPV detection of each group to the location of the junction between the squamous epithelium of the ectocervix and vagina and the columnar epithelium of the endocervical canal. Models evaluated the independent effects of amount of exposed columnar epithelium (ectopy) and age on the presence of alpha9 or alpha3/alpha15 types. Prevalence of alpha9 types (7.6%) peaked in the youngest women, declined in middle-aged women, and then increased slightly in older women. By contrast, prevalence of alpha3/alpha15 types (7.6%) tended to remain invariant or to increase with increasing age. Detection of alpha9 infections increased (P(trend) < 0.0005) but alpha3/alpha15 infections decreased (P(trend) < 0.0005) with increasing exposure of the columnar epithelia. Older age and decreasing cervical ectopy were independently positively associated with having an alpha3/alpha15 infection compared with having an alpha9 infection. These patterns need to be confirmed in other studies and populations. We suggest that these genetically distinct groups of HPV types may differ in tissue preferences, which may contribute to their differences in carcinogenic potential.

Common variants in immune and DNA repair genes and risk for human papillomavirus persistence and progression to cervical cancer.

BACKGROUND We examined host genetic factors to identify those more common in individuals whose human papillomavirus (HPV) infections were most likely to persist and progress to cervical intraepithelial neoplasia grade 3 (CIN3) and cancer. METHODS We genotyped 92 single-nucleotide polymorphisms (SNPs) from 49 candidate immune response and DNA repair genes obtained from 469 women with CIN3 or cancer, 390 women with persistent HPV infections (median duration, 25 months), and 452 random control subjects from the 10,049-woman Guanacaste Costa Rica Natural History Study. We calculated odds ratios and 95% confidence intervals (CIs) for the association of SNP and haplotypes in women with CIN3 or cancer and HPV persistence, compared with random control subjects. RESULTS A SNP in the Fanconi anemia complementation group A gene (FANCA) (G501S) was associated with increased risk of CIN3 or cancer. The AG and GG genotypes had a 1.3-fold (95% CI, 0.95-1.8-fold) and 1.7-fold (95% CI, 1.1-2.6-fold) increased risk for CIN3 or cancer, respectively (P(trend) = .008; referent, AA). The FANCA haplotype that included G501S also conferred increased risk of CIN3 or cancer, as did a different haplotype that included 2 other FANCA SNPs (G809A and T266A). A SNP in the innate immune gene IRF3 (S427T) was associated with increased risk for HPV persistence (P(trend) = .009). CONCLUSIONS Our results require replication but support the role of FANCA variants in cervical cancer susceptibility and of IRF3 in HPV persistence.

Comparison of the SPF10-LiPA System to the Hybrid Capture 2 Assay for Detection of Carcinogenic Human Papillomavirus Genotypes among 5,683 Young Women in Guanacaste, Costa Rica

ABSTRACT The objective of this analysis was to compare the performance characteristics of two human papillomavirus (HPV) DNA detections assays, the Hybrid Capture 2 assay (HC2) and the SPF10 assay, for the detection of carcinogenic HPV. Data are from the enrollment visits of women who participated in the randomized, double-blind, placebo-controlled phase III HPV16/18 Vaccine Trial in Guanacaste, Costa Rica. We compared the results of HC2 and SPF10 testing of cervical specimens. Since the line probe assay (LiPA) detection system does not distinguish between HPV type 68 (HPV68; which is targeted by HC2) and HPV73 (which is not targeted by HC2), for SPF10-LiPA, we defined the carcinogenic HPV types as the 12 HC2-targeted types (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59), HPV68/73, and the HC2-cross-reactive, carcinogenic type HPV66. The kappa values and the performance characteristics for the detection of cervical abnormalities were ascertained. Paired observations were available for 5,683 sexually active, young women (median age, 21 years). The prevalence of carcinogenic HPV types was 35% (n = 1,962) by HC2 and 35% (n = 2,003) by SPF10-LiPA. There were no differences in the prevalence of carcinogenic HPV types by HC2 and SPF10-LiPA among women with normal, atypical squamous cells of undetermined significance and high-grade squamous intraepithelial lesion cytology. Among women with low-grade squamous intraepithelial lesion cytology, HC2 was more likely to test positive than SPF10-LiPA for the carcinogenic HPV types (87% and 79%, respectively; P = 0.001) as a result of HC2 cross-reactivity with HPV types 40, 43, 44, 53, 54, 60, 70, and 74. The crude agreement between the two assays was 88%, with a kappa value of 0.75 (95% confidence limits, 0.73 to 0.76). We observed very good agreement between HC2 and SPF10-LiPA for carcinogenic HPV type detection.

A population-based study of vaginal human papillomavirus infection in hysterectomized women

We compared point prevalences and determinants of human papillomavirus (HPV) DNA detection by testing enrollment vaginal specimens from hysterectomized women (n=569) and enrollment cervical specimens from nonhysterectomized women (n=6098) >or=30 years old, using MY09/MY11 L1 consensus-primer polymerase chain reaction. The subjects were participating in a population-based cohort study (n=10,049) in Guanacaste, Costa Rica, that was initiated in 1993. Non-cancer-associated HPV types, especially types 61, 71, and 72, were detected more frequently in the vaginal specimens from hysterectomized women (23.7% [95% confidence interval [CI], 20.3%-27.4%]) than in the cervical specimens from nonhysterectomized women (16.7% [95% CI, 15.7%-17.6%]) (P=.0001). There was no difference between the prevalences of cancer-associated HPV types in hysterectomized women and those in nonhysterectomized women; in both groups, the prevalence of HPV DNA was greater in women with multiple lifetime sex partners. We infer from our data that the cervical transformation zone may not be needed for cancer-associated HPV infection but may be uniquely susceptible to HPV-induced carcinogenesis; we also infer that specific phylogenetic groups of HPV (i.e., A3/A4/A15) may have a predilection for vaginal epithelium.