Pregnancy Bliss | Reproductive Health Answers
Whilst, of late, the focus has been on the newly introduced cervical cancer prevention vaccine (and rightly so), research work has been going on with regard to the best way of helping those women who fall outside the target group. It is an accepted fact that most women in their late twenties upwards will have been exposed to the HPV virus and therefore unlikely to benefit from the vaccine. This virus is the cause of the vast majority of cervical cancers. Focusing on its detection makes sense.
Now, a large study funded by the European union and Italian government has produced interesting results. The results show that for women 35 years of age or older, human papillomavirus (HPV)-based screening is more effective in detecting high-grade cervical lesions and preventing invasive cervical cancer than cytology. However, this screening modality is less effective in younger women because it can lead to overdiagnosis of cervical intraepithelial neoplasia (CIN), which is likely to regress on its own.
The study results were published in the Lancet Oncology January 19, 2010 online edition. The researchers conclude that for women older than 35 years, HPV testing should replace cytology in routine screening. An accompanying editorial notes that HPV testing "shows a great deal of promise to revolutionise cervical cancer screening, especially in developing countries."
In the first part of the trial, a similar number of invasive cancers were detected in the group screened with cytology (n = 9) and that screened with HPV testing (n = 7). But in the second round of screening, there were no invasive cancers detected in the HPV group and 9 in the cytology group, suggesting that HPV-based screening is more effective in preventing progression to cancer because of earlier detection of clinically relevant lesions and treatment of pre-cancers.
"I think that there is sufficient evidence to shift to stand-alone HPV testing," said lead author Guglielmo Ronco, MD, from the Centro per la Prevenzione Oncologica in Turin, Italy. "Cytology should be used only to triage HPV-positive women."
It is different for younger women
Dr. Ronco does not recommend any changes in the screening paradigm for younger women. Because of the tendency of spontaneous regression of many ‘abnormal’ lesions which are detected in women in the younger age groups, the current screening and monitoring regime appears to be best for them. He added; "In the future, research on biomarkers could allow us to identify which CIN2 cases have the potential to progress, so as to avoid over-treatment."
Intervals between screenings
The researchers also conclude that intervals between cervical screenings can be extended with HPV testing, but more follow-up is needed to define how long screening intervals can be safely extended. "In my view, there is already evidence to say that 5-year intervals are safe," said Dr. Ronco.
HPV testing is more sensitive but less specific than cytology for detecting high-grade CIN. When HPV DNA testing is used as a primary screening strategy, followed by cytological triage and repeat screening for persistent HPV type-specific infection, the accuracy of cervical cancer screening could be increased.
HPV testing might also be the most effective method of cervical cancer screening in low-resource settings, where it has been shown to significantly reduce the incidence of invasive cervical cancer. Cervical cancer continues to be a major killer of women in many developing countries.
"We advocate that clinical management be based on estimating a woman's individual risk of cervical precancer, rather than complex algorithms," they write. "Data from the current study could be used to develop risk estimates to make the promise of more effective and cost-effective cervical cancer prevention a reality."
Dr. Ronco agrees. "We are conducting a full cost-effectiveness analysis and, clearly, prolonged screening intervals will contribute to reducing the overall costs," he said. "Another point is the economic and human cost of diagnostic work-up and treatment."
"Appropriate management of HPV-positive women is crucial and, clearly, these women should not be directly referred to colposcopy," Dr. Ronco added. "Nevertheless, there is a need for research in order to optimize screening, and I expect substantial improvements in this field in the near future."
For younger women, the HPV vaccine is the future.