Screening for cervical cancer with a more sophisticated test may offer greater protection than the current test, research suggests.
Cervical screening aims to prevent invasive cervical cancer by detecting abnormalities in a woman's cervix that can be a precursor to cancer. The abnormalities can be caused by infection with human papilloma virus (HPV), which is sexually transmitted and usually harmless.
Currently, cervical cancer screening programs in Canada use a Pap test that collects cells from the cervix to look at under a microscope to check for abnormalities.
In HPV-based screening, cervical cells are collected the same way as in a Pap but are tested for the presence of high-risk strains of HPV.
Studies have shown HPV screening picks up more cervical cancer precursors than the Pap smear. But until now, no study could provide reliable estimates of the effectiveness of HPV screening compared with traditional screening, called cytology.
In Saturday's issue of the medical journal Lancet there is an article about researchers analyzing data from trials involving 176,464 women in England, Itlay, the Netherlands and Sweden.
"HPV-based screening prevented more invasive cervical cancers than did cytology," Dr. Guglielmo Ronco, from the Center for Cancer Epidemiology and Prevention in Turin, Italy, and his co-authors concluded.
Increased protection against invasive cervical cancer was greatest in women aged 30 to 35 years, and HPV screening every five years proved more beneficial in identifying invasive cancers of the cervix compared with Pap screens done every three years.
Introducing HPV testing
The authors recommended implementing HPV-based cervical screening with triage — folllowup exams for women who test positive — from age 30 at intervals of at least five years.
In a journal commentary published with the study, Sandra Isidean and Eduardo Franco of McGill University in Montreal said HPV-based screening gives comfort to most women who have a negative result.
The future of cervical cancer screening in developed countries will likely include HPV testing, Isidean and Franco said.
"With economies of scale that come with broad implementation of primary HPV testing (which will foster competition among various HPV tests) and the lengthening of screen intervals, cervical cancer screening might end up costing countries less money while providing greater safety than with conventional cervical cytology," the commentators concluded.
But they said there are logistical challenges, such as:
- Settling on the type of HPV screening to use.
- Determining appropriate screening ages and intervals.
- Defining triage and management policies for women who are HPV positive.
The research was funded by the European Union, the Belgian Foundation Against Cancer, KCE-Centre d'Expertise, IARC, The Netherlands Organization for Health Research and Development and the Italian Ministry of Health. Franco has been a consultant or member of advisory boards for companies involved in HPV testing, diagnostics and vaccination.