HPV Testing More Sensitive Than Cytology When Screening for Cervical Neoplasia

By Karla Gale

NEW YORK MAR 25, 2008 (Reuters Health) - For initial cervical cancer screening, testing for human papillomavirus (HPV) is more sensitive than conventional cytology, according to an Italian study published in the Journal of the National Cancer Institute for April 2. However, HPV-positive lesions often resolve among women below 35 years of age.

In the first phase of the New Technologies for Cervical Cancer Screening study (NTCC), Dr. Guglielmo Ronco, from Centro per la Prevenzione Oncologica in Turin, and his associates compared conventional cytology with cytology plus HPV testing.

In the second recruitment phase, more than 49,000 subjects were randomly assigned to cytological testing or HPV-DNA testing alone.

"Women aged 35-60 followed the same protocol (referral for colposcopy) in the two phases if HPV positive," Dr. Ronco told Reuters Health. "When pooling the results of the two phases, HPV testing shows a clear gain in sensitivity compared to conventional cytology -- HPV testing detects more than 3 high grade lesions when cytology detects 2. The loss in the positive predictive value -- therefore the increase in the number of colposcopies needed to detect a high grade lesion -- was limited."

However, women aged 25-34, if HPV positive, were managed differently in the two phases. During phase 1, they were directly referred to colposcopy only if cytology was also abnormal, while those with normal cytology repeated the test after one year.

"With this approach the gain in sensitivity versus cytology was similar to that observed at older ages (about 50%)," Dr. Ronco said. "During phase 2, all HPV-positive women were directly referred to colposcopy. With this approach HPV testing detected over 3 times more high-grade lesions than cytology, suggesting that most of the lesions detected with the phase 2 approach will regress spontaneously" in younger women.

The authors propose that direct referral of young women with positive HPV test results to colposcopy may thus represent over-treatment.

Longer follow-up is required before HPV testing can be recommended as a substitute for conventional cytology in routine practice, Dr. Ronco noted.

"I think that the present situation authorizes the start of large demonstration projects in order to monitor compliance, referral rates to colposcopy, detection rates and possible adverse effects (over-treatment and psychological harms)," he explained. "This evaluation requires a screening setting that is capable of following the screened women."

"In any case," Dr. Ronco concluded, "younger HPV-positive women should be referred to colposcopy only if cytology is positive or if HPV testing remains positive after 1 year."

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