Technical Notes
It has been estimated that 75% of women have been exposed to either low-risk or high-risk HPV at some time in their lives.
[Koutsky L. Epidemiology of genital human papillomavirus infection. Am J Med. 1997; 102:3–8.]
The most common outcome for a young woman acquiring an HPV infection is to immunologically clear it in 8 to 24 months. Once the cervix is infected with a type of HPV that can cause malignant growth, if it is not cleared, there is typically a latent period that lasts many years.
[Waxman GL, Guidelines for cervical cancer screening: History and scientific rationale. Clinical Obstetrics and Gynecology 48 (1): 77–97 (2005)]
In one typical study, the median duration of HPV infections was 8 months, with 70% no longer infected by 12 months. By 24 months, 81% had cleared the HPV infection . HPV regression rates of over 90 percent within two years have been reported in college populations.
[Ho GY, Bierman R, Beardsley L, et al. The natural history of cervical papillomavirus infection in young women. N Engl J Med. 1998;338:423–428.]
The sensitivity of a single Pap test, conventional or liquid-based, has been reported to vary between 51% and 88%.
[Clavel C, Masure M, Bory JP, et al. Human papillomavirus testing in primary screening for the detection of high-grade cervical lesions: a study of 7932 women. Br J Cancer. 2001;84:1616–1623.]
[McRory DC, Batcher DB, Bastian L, et al. Evaluation of Cervical Cytology: Evidence Report/Technology Assessment No. 5. Rockville, MD: Agency for Healthcare Policy and Research; 1999: AHCPR Publication no. 99-E010.]
3.5 million women each year are diagnosed with a cervical abnormality requiring additional follow-up or evaluation.
[JAMA. 2002;287:2120-2129]
From 1977 to 1992, the number of new cases of cervical cancer in the under-40 age group in Finland was stable. In the next ten years, that number more than doubled.
[Finnish Cancer Registry 2004, Cancer Society of Finland]
A recent study of HPV types in East Africa has found that the most common HPV types were HPV 52 (17.9%), HPV 16 (14.7%), and HPV 35 (11.6%), all cancer-producing types. In contrast to other studies, HPV 16 was not the most prevalent type and the authors conclude that the high prevalence of HPV 52 and 66 in this East African population warrants further research to tailor vaccines to take into account regional variations. Among women with high-grade lesions, the most common HPV types were HPV 16 (35.7%), HPV 52 (25%), and HPV 35 (17.9%).
[De Vuyst, H. et al. Distribution of human papillomavirus in a family planning population in Nairobi, Kenya. Sexually Transmitted Diseases 30(2):137–142 (February 2003).]
