Rationale
Cervical cancer has a long route from HPV infection to carcinogenesis, often over 10 years, and the process is well understood. It is the third most common gynaecological malignancy after endometrial and ovarian cancers. Cervical cancer, if diagnosed at the pre-invasive (cervical intraepithelial neoplasia or CIN) or early invasive stage, is readily curable with potential preservation of fertility. Advanced stages eliminate the ability to carry a pregnancy; metastatic disease is incurable. Tests for detection of CIN and cervical cancer are readily available (Pap smear).
Arguments against screening are minimal. The main ongoing impact at the moment is the introduction of the HPV vaccine (quadravalent or bivalent types) which should significantly reduce the indicen of cervical cancer by eliminating the majority of infections of HPV 16 and 18.
Evidence
Papanicolaou Screen
There are no randomised controlled trials. Instead, large observations series demonstrate a marked reduction in cervical cancer mortality after introduction of Pap smear screening into a population. Reductions in incidence and mortality from 50-90% have been reported in many Western countries after introduction of screening.
HPV screening
HPV screening instead or as an adjunct to Pap smear screening has been evaluated in randomised trials.
- When used primarily, it results in a higher number of colposocopies, which are negative
- When used primarily or with Pap smear, it allows earlier detection of high grade lesions
- It may increase the number of positive results but the impact on survival is not clear
Therefore HPV screening can not be recommended, especially as the primary test.
