Study confirms danger of persistent HPV infection
MedWire News: Taiwanese study results confirm that persistent detection of human papillomavirus (HPV) infection in women over 30 years significantly increases their risk for cancer compared with women who repeatedly test negative, or who have "incident" infection.
"Our findings suggest that, if upon testing, an HPV infection is found, re-testing 2 years later would provide useful guidance as to the duration of infection and its risk," say Chien-Jen Chen (National Taiwan University, Taipei) and colleagues.
"The challenge that remains is to devise optimal management guidelines for HPV-positive women, which may include a careful wait-and-see approach to monitor viral persistence versus clearance," they add, in the Journal of the National Cancer Institute.
The team used data for 10,123 women aged 30-65 years, all of whom were given a baseline examination during 1991 through 1992, and 6923 of whom were re-examined 2 years subsequently.
After a mean follow-up of 14.5 years, 68 women were diagnosed with incident cervical cancers giving an incidence rate of 46.4 per 100,000 person-years of follow-up.
The corresponding rates for women who were HPV positive at baseline versus those who were not were 252.0 and 15.7, giving a 16.2-fold increase in risk for cervical cancer among the former group of women, report the researchers.
HPV16 was the most commonly detected HPV type at baseline before a cancer diagnosis, with a cumulative risk for cancer development after 16 years follow-up of 13.5%.
Persistence of the same genotype-specific HPV at the second examination predicted extremely high incidences and hazard ratios of cervical cancer. Specifically, hazard ratios ranged from 2.1 for HPV58 to 12.8 for HPV56, compared with baseline-only infection.
The overall hazard ratio for cervical cancer among women with type-specific persistence of a known carcinogenic HPV infection was large, at 75.4.
HPV-negative women's risk for developing cervical cancer was very low, at 0.26%, and developing an HPV infection at the second examination also rarely led to cervical cancer, with only eight women in this circumstance developing it.
The risk for developing cervical cancer among women with persistent HPV infection (same genotype at both examinations) increased with age, with cumulative risks among 30-44-, 45-54-, and 55-65-year-old women of 5.5%, 14.4%, and 18.1%, respectively, translating to respective hazard ratios of 37.8, 71.2, and 190.8.
Chen et al emphasize that persistence of HPV infection is what gives "critical magnitude" to a woman's risk for cervical cancer.
However, they add that whilst persistence cannot be overemphasized, "many women and their clinicians are reluctant to wait for clearance because the first positive result (especially at older ages) does indicate increased risk compared with a negative result."
By Sarah Guy