Vaccins anti-papillomavirus et prévention du cancer du col de l’utérus

High prevalence of HPV infection in the remote villages of French Guiana: an epidemiological study

Cervical cancer is the second most frequent cancer in women in French Guiana. Studies have shown that populations living in the remote areas of the interior have early sexual debut and that multiple sexual partnerships are common. The objective of the present study was thus to determine the prevalence of human papillomavirus (HPV) infection in these areas. A study was conducted in women aged 20-65 years with previous sexual activity. Women were included on a voluntary basis after using local media and leaders to inform them of the visit of the team. HPV infection was defined by the detection of HPV DNA using the Greiner Bio-One kit. In addition to HPV testing cytology was performed. The overall age-standardized prevalence rate was 35%. There was a U-shaped evolution of HPV prevalence by age with women aged >50 years at highest risk for HPV, followed by the 20-29 years group. Twenty-seven percent of women with a positive HPV test had normal cytology. Given the high incidence of cervical cancer in French Guiana and the high prevalence of HPV infections the present results re-emphasize the need for screening for cervical cancer in these remote areas. Vaccination against HPV, preferably with a nonavalent vaccine, also seems an important prevention measure. However, in this region where a large portion of the population has no health insurance, this still represents a challenge.

Occupational trichloroethylene exposure and cervical pathology: a case-control study

OBJECTIVES

Trichloroethylene (TCE) is suspected of association with elevated risk of cervical cancer. A case-control study was performed in a geographical area in which occupational TCE exposure is high. The study objective was to analyze the correlation between occupational TCE exposure and cervical cancer (including precancerous conditions).

METHODS

Case and control subjects were recruited by gynecologists. General and occupational data were collected by telephonic interviews. An industrial hygienist assessed occupational TCE exposure on a task-exposure matrix. Analysis focused on occupational TCE exposure at various levels and on cumulative dose. Multivariate analysis was performed to take account of the various risk factors.

RESULTS

In total, 67 case and 67 age-matched control subjects were included. Mean age was 36 years in both groups. Five of the possible general risk factors correlated significantly with cervical dysplasia or cancer: number of partners, history of genital or anal wart, interval between first period and first sexual relation, parity, and body mass index, the last three showing inverse correlation. Elevated risk was found in women who had had jobs as manual workers according to the PCS French classification (professions and socioprofessional categories), and production and related workers according to ISCO classification (International Standard Classification of Occupations), with odds ratios (ORs), adjusted on general and medical risk factors, of 7.68 [95% confidence interval (CI): 1.39-42.54] and 7.48 (1.30-43.24), respectively, among skilled service sector workers; the adjusted OR was close to significance, at 4.67 (95% CI: 0.92-23.67). No occupational sectors were significantly associated with elevated risk. In all, 17 (25.4%) case and 15 (22.4%) control subjects were exposed to TCE: raw OR = 1.17 (95% CI: 0.54-2.52), adjusted OR = 1.51 (95% CI: 0.42-5.41). There was no significant correlation between cumulative dose and exposure time.

CONCLUSIONS

The study found no significantly increased risk of cervical dysplasia or cancer associated with occupational TCE exposure.

[Clearance, persistence and recurrence of HPV infection]

Cervical HPV infection is a common sexually transmitted infection. Most women are infected shortly after beginning their first relationship, with the highest prevalence seen in women under 25 years of age. Thereafter, prevalence decreases rapidly. HPV infections are usually transient; but several factors increasing persistence were identified as host factors (genetic or acquired as age, immunodepression, oral contraception, smoking) and viral factors (genotype, variants, viral load, integration...). Although it is now widely admitted that a persistent infection with a high-risk HPV type is necessary for the development of high-grade cervical intraepithelial neoplasia and invasive disease, whether persistent HPV infections are characterized by the continuing detection of HPV, or by a state of viral latency during which the virus remains undetectable only to reappear later remains unknown. The distinction between a persistent and transient infection is arbitrary depending from both the time of sampling in relation to the natural history of the infection and the interval between samples. The longitudinal studies show that "recurrent" HPV infections offer no evidence that the recurrent episode is correlated with reemergence of the same strain or another strain of the same genotype (wild or variant), but the sequential detection of other HPV type is common. The studies offer no evidence of competition between HPV types but frequently show an increased risk of acquisition of new HPV types in patients already infected compared with those who are HPV-negative.

[Anti human-papillomavirus vaccines: concepts, aims and trials]

PURPOSE

Human Papillomaviruses (HPV) are epitheliotropic for stratified malpighian epithelia such as those of the cervix. Among them, oncogenic viruses are detectable in 99.7% of cervical cancers. A great priority is to develop a vaccine either against primary infection (preventive vaccine) allowing protection against HPV infection or therapeutic vaccine in order to kill previously infected or transformed keratinocytes.

CURRENT KNOWLEDGE AND KEY POINTS

Preventive vaccines against HPV contain virus like particles (VLP) 16 and 18 and induce a high titer of blood anti-VLP antibodies. They were recently tested in humans and have shown true efficiency for the prevention of cervical cancer. The therapeutic vaccines are therefore currently being developed in order to increase anti-HPV natural CD4+ and CD8+ T-cell immunity in women infected during their sexual activity.

FUTURE PROSPECTS

The perspective of the prophylactic vaccines is to decrease both genital HPV infection and cervical cancer. The impact of preventive vaccine must be carefully analyzed in order to prevent collateral side effects. The therapeutic vaccines have also a future in women already infected by HPV and might have an efficiency similar to surgery in the treatment of cervical intraepithelial neoplasia.