30/06/2010

Giornata di studio sui risultati Progetto di Cooperazione L.R. 19/96.
Giornata di studio sui risultati Progetto di Cooperazione L.R. 19/96 Franca Piras[1], Michela Piga[2], Antonella De Montis[3], Manuela Atzori[3], Marco Pittau[4], Daniela Murtas[1], Luigi Minerba[5], Cristina Maxia[1], Maria Teresa Perra[1], Paola Sirigu[1]

Introduction:
Benin has a population of 2.22 millions women ages 15 years and older who are at risk of developing cervical cancer. Current estimates indicate that every year 561 women are diagnosed with cervical cancer and 448 die from the disease. Cervical cancer ranks as the 2nd most frequent cancer among women in Benin, and the 2nd most frequent cancer among women between 15 and 44 years of age. Human papillomavirus (HPV) infection is now a well-established cause of cervical cancer. Data is not yet available on the HPV burden in the general population of Benin. This report, for the first time, provides informations for Benin on HPV-related statistics, cervical cancer screening practices. Human papillomavirus (HPV) type-specific distribution was evaluated in cervical swabs collected from 725 women from the Benin undergoing voluntary screening and correlated with cyto-histological abnormalities. Only 351 samples were valuable for HPV DNA detection and 493 for PAP test.

Material and methods:
Conventional cervical smears were resuspended in ThinPrep preservative solution and subjected to cytological screening by PAP TEST and to molecular analysis by BIOCHIP (Prodect® Chip HPV Typing)Statistical analysis was performed by Statistical Package for the Social Sciences (SPSS) 15.0 software to establish association between PAP test reports with HPV status. Results were summarized as odds ratio (OR) with corresponding 95% Confidence Interval (CI). Samples were subjected to molecular analysis by BIOCHIP (Prodect® Chip HPV Typing kit cod. BCS300776 bcs BIOTECH S.p.A.), to determine samples positivity or negativity for DNA L1 and E6/E7 Papillomavirus sequence. The system define also the virus genotype thanks to the presence of specific probes for 14 viruses with a high-medium oncogene risk, and 5 specific probes for viruses with a low oncogene risk on the region L1. DNA was extracted from the sample using Prodect® HPV Extraction kit (code BCS291509HPV-100 bcs BIOTECH S.p.A.) and amplified with PCR MULTIPLEX. PCR product were put in the biochip wells for hybridization with specific probes pre-spotted into the 96 microplate wells. The hybridization was followed by a colorimetric reaction. The Biochip reading and the pattern interpretation were automatically performed by a reader and software (Prodect® Bcs Biochip Reader code BCS090786 bcs BIOTECH S.p.A).

Results and discussion:
HPV-16 is the most common HPV type both in women with normal cervical cytology and in those with cervical lesions or cancer, followed by HPV-18 in Europe, Central and South America, HPV-52 and HPV-58 in Asia, and HPV-53 and HPV-52 in Northern America. The pattern of HPV type distribution may vary even among countries and regions, being related to sexual habits and migrations of people. HPV types 16 and 18 are responsible for about 70% of all cervical cancer cases worldwide. In our study, HPV DNA was detected in 35% of the samples, 90% of which had high-risk HPV infection, 36% had multiple infection, and 64% single infection. Our data show that in Benin the most common high risk HPV types were HPV-59 (26%) and HPV-16 (19%), followed by HPV-35 (16%), HPV-18 (15%), HPV-58 (11%), HPV-45 (9%), HPV-56 (7%), HPV-73 (6%), HPV-51 (3%), HPV-31, -33, -52 (2%) in women with both normal and abnormal cytology. In the women who performed both HPV typing and PAP test, HPV DNA was found in about 27.9% % negative PAP test and in 42.8% of positive PAP test. HPV infected women have an approximately two fold risk of having cervical lesions (Odds ratio 2.3). No relation was detected between age and presence of HPV. These data provide information on HPV type distribution in women from Benin and indicate that the epidemiology of HPV infection in this area is different from other regions. Besides HPV-16 and HPV-18, which are targeted by the currently available HPV vaccines, other high-risk HPVs, such as HPV- 59 and HPV-35, appear to be mostly diffused in the Benin women and to be associated with cervical lesions. These HPVs should be taken into consideration in the development of enhanced vaccines with larger type cover.

[1] Department of Cytomorphology, University of Cagliari, Italy;
[2] Department of Pathology, ‘SS. Trinità’ Hospital, Cagliari, Italy;
[3] Research Laboratories, bcs Biotech, Cagliari, Italy;
[4] Cloning Laboratory, bcs Biotech S.p.A., Cagliari, Italy;
[5] Department of Public Health, University of Cagliari, Italy.