This according to a new national population study published online in the prestigious scientific periodical, The British Medical Journal (BMJ).
“We found that women who die of cervical cancer have usually not been screened for a long time,” says research leader Professor Pär Sparén of the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet. “This is important to know for women who are hesitant about screening and for the sake of future changes to screening programmes.”
Around 450 women develop cervical cancer every year in Sweden, of whom about 140 die. Less than twenty of the vast majority of women (about 80 per cent) who undergo cervical screening every three years develop incurable and fatal cervical cancer. Moreover, of the cases discovered during routine screening before symptoms appear fewer than five every year are incurable.
In this present study, the researchers examined all new cases (a total of 1,230) of cervical cancer in Sweden over three years (1999-2001) using data from the National Quality Register for Cervical Screening. The project is part of the ACCES (Advancing Cervical Cancer Eradication Strategies) project, which was set up to monitor and evaluate the long-term effects of the cervical screening programme and vaccination programme against human papillomavirus (HPV), which causes cervical cancer.
The results of the study show, that women with symptom-discovered cervical cancer have a much better chance of being cured if they have previously had regular smear tests than if they have not taken part in any screening programme. About 92 per cent of the women with cervical cancer discovered through screening (i.e. before the appearance of symptoms), are cured from their cancer, even those who undergo screening for the first time.
“This clearly shows that the positive results for cervical cancer after the introduction of screening have nothing to do with the overdiagnosis of benign cancers,” says lead author Bengt Andrae, consultant at Gävle Hospital’s gynaecological clinic and researcher at Karolinska Institutet. “What it does show is that early diagnosis significantly improves the chance of successful treatment. This is a powerful argument for taking a Pap smear when invited to cervical screening, even if you feel healthy.”
In a leader column in the same issue of BMJ, prominent European epidemiologists comment that the method used in the nationwide Swedish study should be seen as a template for EU-recommended screening programme audits. The study has been financed by, amongst other bodies, the Swedish Cancer Society, and the Research and Development Centre at Uppsala University/Gävleborg County Council. The ACCES project is being financed by the Swedish Foundation for Strategic Research (SSF). Dr Andrae is also chair of the committee for cancer prevention in the Swedish Society for Obstetrics and Gynaecology; Professor Sparén is director of the National Quality Register for Cervical Screening.
Screening and cervical cancer cure: population based cohort study
BMJ online 2 March 2012