The relationship of human papillomavirus (HPV) detection to pap smear classification of cervical-scraped cells in asymptomatic women in northeast Thailand

Human Papillomavirus Genotypes and thep53Codon 72 Polymorphism in Cervical Cancer of Northeastern Thailand

Human papillomavirus (HPV) infection including sub-strain identification was studied in patients with squamous cell cervical cancer (SCCA) in Northeastern Thailand. Subjects were 90 cases of SCCA and 100 healthy controls. Prevalence of high-risk group of HPV infection in the controls and the SCCA patients were 13.0% and 86.7%, respectively. The HPV infection significantly increased the risk for cervical cancer 43.5-fold (95% confidential interval: 17.5-110.6; P <0.00001). Among HPV carrier patients with SCCA (n = 78), HPV-16 was also prominent (70.5%) followed by HPV-18 (23.1%). There was no statistical difference in the subtype distribution between the SCCA and the control groups. There was no significant association between genotype distribution of the p53 codon 72 polymorphism and HPV infection. HPV infection was confirmed as a critical risk factor for cervical cancer development in Northeast Thailand. Since polymorphism of the p53 itself as well as in combination with HPV infection may not be a genetic risk for cervical cancer, much attention should be paid to other risk factors such as sexual behavior and smoking.

Age-specific prevalence of infection with human papillomavirus in females: a global review

PURPOSE

Global data on age-specific prevalence of human papillomavirus (HPV) infection overall, and for high-risk HPV types 16 and 18, are essential for the future implementation of HPV prophylactic vaccines for cervical cancer prevention.

METHODS

A systematic review of peer-reviewed publications was conducted to summarize worldwide data on genital HPV-DNA prevalence in women. Studies with clear descriptions of polymerase chain reaction or hybrid capture detection assays were included.

RESULTS

A total of 346,160 women were included in 375 studies. Of 134 studies with age-stratified HPV prevalence data (116 low sexual risk populations, 18 high sexual risk populations), over 50% were from Europe and the Middle East (38%) and North America (19%), with smaller proportions from Asia and Australia (21%), Central and South America (11%), and Africa (10%). Across all geographical regions, data on HPV prevalence were generally limited to women over 18 years of age. Consistently across studies, HPV infection prevalence decreased with increasing age from a peak prevalence in younger women (< or =25 years of age). In middle-aged women (35-50 years), maximum HPV prevalence differed across geographical regions: Africa (approximately 20%), Asia/Australia (approximately 15%), Central and South America (approximately 20%), North America (approximately 20%), Southern Europe/Middle East (approximately 15%), and Northern Europe (approximately 15%). Inconsistent trends in HPV prevalence by age were noted in older women, with a decrease or plateau of HPV prevalence in older ages in most studies, whereas others showed an increase of HPV prevalence in older ages. Similar trends of HPV 16 and/or 18 prevalence by age were noted among 12 populations with available data.

DISCUSSION

Genital HPV infection in women is predominantly acquired in adolescence, and peak prevalence in middle-aged women appears to differ across geographical regions. Worldwide variations in HPV prevalence across age appear to largely reflect differences in sexual behavior across geographical regions. Further studies of HPV prevalence in adolescents are needed for all geographic regions.

Human papillomavirus type distribution in women from Asia: a meta-analysis

The aim of this study was to determine human papillomavirus (HPV) type distribution in women with and without cervical neoplasia from Asia and to estimate the potential future impact of an HPV 16/18 prophylactic vaccine in this region. A meta-analysis was conducted including 79 studies using polymerase chain reaction to detect HPV types. A total of 5954, 1653, 958, and 16,803 women with invasive cervical cancer (ICC), high-grade squamous intraepithelial lesions (HSIL), low-grade squamous intraepithelial lesions (LSIL), and normal cytology or histology were included, respectively. Type-specific prevalence of HPV types 6, 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68, 70, 73, and 82 were estimated and stratified by cervical lesion grade. Overall HPV prevalence was 85.9%, 81.0%, 72.9%, and 14.4%, respectively, in women with ICC, HSIL, LSIL, and normal cytology/histology. In ICC, HPV 16 was the predominant type (52.4%), followed by HPV 18, 58, 33, 52, 45, 31, and 35. The estimated HPV 16/18-positive fraction was 66.9%, 40.4%, 26.7%, and 3.3% in women with ICC, HSIL, LSIL, and normal cytology or histology, respectively. In ICC, the estimated HPV 16/18-positive fraction was about 70% in all Asian geographic regions, with the exception of Japan (51.3%). HPV 16/18 vaccines are estimated to provide about 67% protection against ICC in Asia. HPV 58 and 52 were among the five most common types in ICC in eastern and southeastern Asia but not in south central Asia. After HPV 16 and 18, the next most six common HPV types were 58, 33, 52, 45, 31, and 35 that accounted for additional 20% of cervical cancer cases in Asia. For optimal population coverage, these HPV carcinogenic types should be considered for second-generation HPV prophylactic vaccines.

Immunocytochemical staining of p16INK4a protein from conventional Pap test and its association with human papillomavirus infection

The p16INK4a protein is immunocytochemically detected in liquid-based (LB) specimens as a diagnostic marker of cervical dysplasia and neoplasia. Its up-regulation is promoted by high-risk human papillomavirus (HR-HPV) infection. We aimed to detect p16INK4a on conventional Papanicolaou (Pap) test (CPT) slides and to determine the relationship between its overexpression and HR-HPV infection. CPT and LB Pap test (LBPT) slides (165 samples of each) were examined by immunocytochemical staining for p16INK4a. After polymerase chain reaction (PCR), HPV-DNA was genotyped by dot blot hybridization. The CPT slides displayed more numerous dispersed squamous cells and LBPT slides had a clearer background. Positive p16INK4a on CPT occurred in 0% (0/30), 52.5% (21/40), 54.3% (19/35), 100% (30/30), and 100% (30/30) in normal, atypical squamous cells of undetermined significance (ASCUS), low-grade squamous intraepithelial lesions (LSILs), high-grade SILs (HSILs), and squamous cell carcinomas (SCCs) cases, respectively. LBPT slides showed comparable results but were less sensitive. HPV-DNA was detected in 86.7, 70, 45, 57.14, and 10% in SCCs, HSILs, ASCUS, LSILs, and normal cervical cells, respectively. Because HR-HPV was identified in all HPV+ samples of high-grade dysplasia (HSILs and SCCs) and all positive p16INK4a samples infected with HR-HPV, the association of p16INK4a overexpression with HR-HPV infection was confirmed. This study suggests that immunocytochemical staining of p16INK4a on CPT slides is convenient and cost-effective for cervical cancer screening by the detection of dysplastic cells infected with HR-HPV.

Cervical cancer among Hmong women in California, 1988 to 2000

BACKGROUND

The Hmong immigrated to the United States from Laos after the Vietnam conflict ended. Hmong encounter numerous readjustment issues, including health care. Traditional Hmong health beliefs and practices encompass more spiritual than biological etiologies. Hmong usually seek the first course of treatment from traditional healers, as they had in Laos. This practice delays early diagnosis and treatment of disease because biomedicine is used only as a last resort. This study examined cervical cancer incidence, mortality, and other tumor characteristics in the Hmong female population of California between 1988 and 2000.

METHODS

Data from the California Cancer Registry were used to calculate annual average incidence, mortality, and age-specific rates for Hmong women diagnosed with cervical cancer. The population at risk was estimated with linear interpolation using data from the 1990 and 2000 censuses.

RESULTS

Hmong women experienced incidence and mortality rates three and four times higher than Asian/Pacific Islander and non-Hispanic white women, respectively. Fifty-one percent of Hmong women chose no treatment, compared to 5.8% for Asian/Pacific Islander women and 4.8% for non-Hispanic white women. Hmong women aged >/= 40 years carried an unequal burden of cervical cancer. They were more likely to be diagnosed with cervical cancer at later stages and poorer histologic grades, and had a lower survival rate than younger Hmong females.

CONCLUSIONS

Cervical cancer is clearly a public health issue that threatens the health and well-being of Hmong women. Culturally sensitive screening and prevention programs need to be developed to target older Hmong women using bilingual and bicultural Hmong women health educators using verbal communication.

Costs and benefits of different strategies to screen for cervical cancer in less-developed countries

BACKGROUND

About 80% of cervical cancers occur in less-developed countries. This disproportionate burden of cervical cancer in such countries is due mainly to the lack of well-organized screening programs. Several cervical cancer screening strategies have been proposed as more cost-effective than cytology screening. We compared the costs and benefits of different strategies and their effectiveness in saving lives in a less-developed country.

METHODS

We used a population-based simulation model to evaluate the incremental societal costs and benefits in Thailand of seven screening techniques, including visual inspection of the cervix after applying acetic acid (VIA), human papillomavirus (HPV) testing, Pap smear, and combinations of screening tests, and examined the discounted costs per year of life saved (LYS).

RESULTS

Compared with no (i.e., not well-organized) screening, all strategies saved lives, at costs ranging from 121 US dollars to 6720 US dollars per LYS, and reduced mortality, by up to 58%. Comparing each strategy with the next least expensive alternative, VIA performed at 5-year intervals in women of ages 35-55 with immediate treatment if abnormalities are found was the least expensive option and saved the greatest number of lives, with a cost of 517 US dollars per LYS. HPV screening resulted in similar costs and benefits, if the test cost is 5 US dollars and if 90% of women undergo follow-up after an abnormal screen. Cytology (Pap smear) was a reasonable alternative if sensitivity exceeds 80% and if 90% of women undergo follow-up. Compared with no screening, use of a combination of Pap smear and HPV testing at 5-year intervals in women of ages 20-70 could achieve greater than 90% reduction in cervical cancer mortality at a cost of 1683 US dollars per LYS, and VIA could achieve 83% reduction at 524 US dollars per LYS.

CONCLUSIONS

Well-organized screening programs can reduce cervical cancer mortality in less-developed countries at low costs. These cost-effectiveness data can enhance decision-making about optimal policies for a given setting.