Human papillomavirus detection and typing in patients with abnormal pap smears

Abstract

STUDY RATIONALE: Cervical cancer is the most common cancer of women on the African continent and the second most common cancer of women worldwide and in South Africa ’. It has been estimated in 1997 that, among women who received no cervical screening in South Africa, 1 in 26 women were likely to develop cervical cancer . Screening will probably decrease the incidence of cervical cancer by 60% or more . There is a direct relationship between the number of women screened by Pap smears and the decreased incidence of cervical cancer. In Iceland, where more than 90% of women were screened in that time, the incidence decreased by 80%. In Norway, where only 5% of the women were screened, the incidence only decreased by 10% . In South Africa, it is estimated that Pap smears were taken in 18.8% of white women and only 2.6% of black women in 2002 . Real-world obstacles to successful cervical cancer prevention in develo- ping countries involve people more than technologies 3. This can be ma- naged by focusing on system quality management 3. The root causes of poor quality must be examined. Suba et al 3 found causes such as obso- 7 lete supplies, poorly maintained microscopes, insufficient training and suboptimal working conditions. Successful follow-up for screen-positive women has been achieved through the allocation of budgets for dedicated personnel to recontact women with positive test results 3. Human Papillomavirus (HPV) infection is known to cause cervical can- cer. Human Papillomavirus (HPV) infection is also regarded as the most common sexually transmitted infection worldwide, with an estimated life- time risk of 79% for women to contract at least one infection between the ages of 20 and 79 years . Although some men have anal or genital lesions associated with HPV 16 and 18, most men serve as vectors of oncogenic HPV. Male partners may be important contributors to their female partners’ risk of cervical cancer . The 15 HPV types, which are classified as high risk virus types, cause 95 % of all cervical cancer. The High Risk HPV Genotypes are: 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 68, 73 and 82. HPV 16 and 18 together cause around 70 % of all cervical cancer ’. Squamous cell cervical cancer constitutes approximately 80% of cervical cancers . Adenocarcinoma is the second most common histological type and shows a rising incidence, even in developed countries . 8 There is geographical variation in type-specific HPV prevalence 9. HPV16 is the most common type associated with adenocarcinomas, except in Southeast-Asia, where the prevalence of HPV 18 exceeds that of HPV 16. HPV 16, 18, 35, 45and 59 are present in 96% of adenocarci- nomas of the cervix 10. A pooled analysis by Clifford et al 9 showed that the prevalence of high risk HPV types is around 18 % in sub-Saharan Africa, with HPV 16 and HPV 35 present in 8% of women. HPV 31 and HPV 33 were present in 7% of women and HPV 18 was present in 4% of women. Sub- Saharan Africa had the highest prevalence of all HPV types and Europe the lowest. The variation in prevalence of HPV 16 across regions was smaller for HPV 16 than for the other high-risk types. The next common high- risk types were HPV 33 and HPV 56 in Asia, HPV 58 in South America and HPV 31 in Europe 9. This study’s rationale was to ascertain the HPV types prevalent in pa- tients with abnormal Pap smears seen at the Gynaecological Outpatients Clinic at Dr. George Mukhari Hospital, the Gynaecological Oncology Clinic at Dr. George Mukhari Hospital, the Tshepang Clinic at Dr. George Mukhari Hospital and the Setshaba Research Centre of the University of Limpopo – Medunsa Campus in Soshanguve. 9 This study can also act as a pilot study for future studies to test the ef- fectiveness of using high risk HPV types screening as a primary screening method, instead of Pap smears, to identify patients who are at a higher risk to develop cervical cancer and who need further investigations such as Colposcopically directed biopsies.