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The Primary Health Care Act states that municipalities must perform population screenings for cervical cancer in the age group of 30–60 years. In some municipalities also the 25- and 65-year-olds are screened as extra groups.
The Pap test is used to detect pre-cancerous changes in the cervix. The biopsy is taken and possible treatment is applied in a colposcopy examination. More information on colposcopy is at http://www.yths.fi. The Pap test can also reveal less severe changes in the cells that are usually related to tissue repair or a passing HPV infection. In these cases, a new test is recommend after 6 to 12 months.
Information on HPV infection and cervical cancer
Approximately 160–170 new cases of cervical cancer are diagnosed in Finland every year. There is a proven correlation between cervical cancer and HPV infection (Human Papillomavirus, common warts, genital warts). Other known risk factors are sexual activity from an early age, multiple sexual partners, and smoking. Epidemiologically the cancer cases are known to concentrate in the groups that do not take part in the screenings. There are some signs that other gynecological infections may cause cancer to develop, but as of yet there is no unambiguous research information to support this. In addition, the body’s immune system's ability to react to viral changes has an effect on the development and healing of tissue.
HPV infections are common. The lifetime risk for contracting an HPV infection is 70–80% so nearly all Finnish women will have an HPV infection in some point of their lives. 15–25% of young women are HPV positive. The infection usually lasts for 6–24 months and then the virus disappears. Previous infection does not protect from a possible new infection. In some cases the virus remains on the mucous membrane of the uterine orifice for a long time, even for years, without causing any changes. Of these mild changes only a fraction will develop into a pre-cancerous abnormality, and they often heal on their own as the immune response develops. Again, a small amount of these severe pre-cancerous abnormalities become cancers.
The HP viruses can be roughly divided into two main groups: the so called high-risk and low-risk groups. According to the latest studies, high-risk HPV (hr-HPV) is found in 99.7% of the cervical cancer cases. In minor changes, either low risk or high risk viruses are found, but severe pre-cancerous abnormalities are always linked to the presence of a high risk HPV.
New possibilities in early diagnostics
HUS participates in a multicentral study organised by the Cancer Society of Finland where the sample slides are read with the help of a computer. In addition, HUS also has a research project on the usability of a liquid-based Pap – a new application of the Pap and HPV test – in gynecological cytology. HPV testing is not routinely performed in the screening at the moment. A trial on the protective effect of HPV vaccine was also started in Finland.