July 29, 2009- England and Australia- Pap smears in the under-25s has prompted calls from some experts for a review of Australia's cervical cancer screening program.
But other experts say it is unwise to change the system yet and all urge women to keep being screened.
The UK study, reported online today in the British Medical Journal, shows cervical cytology screening in women aged between 20 and 24 has little or no impact on rates of invasive cervical cancer up to age 30.
The study analysed data from 4,012 women with cervical cancer and nearly 8,000 without.
The researchers found that smears were far less effective at preventing cancer in 20- to 24-year-olds than in older women, who saw screening lead to substantial drops in death and incidence of between 60 percent to 80 percent.
Cancer epidemiology professor Peter Sasieni from Queen Mary University of London says, "These data should help policy-makers balance the impact of screening on cancer rates against its harms, such as overtreatment of lesions with little invasive potential."
An accompanying editorial says screening leads to many detected abnormalities in younger women with only a fraction being progressive, but this important fraction which will progress to invasive cancer in the next five years may be missed by screening.
But researchers say there is some uncertainty regarding screening impact on advanced tumors in women under the age of 30.
Despite two other studies backing their findings, one found no evidence of screening being less effective in young women.
English authorities controversially changed their screening program in 2003, inviting women to have their first Pap smear at age 25 instead of 20 to 24. Australia's policy advises starting screening at 20, or two years after starting sexual activity, whichever is later.
Victorian Cytology Service director, Associate Professor Marion Saville, says the study's finding adds weight to the idea that screening women under 25 may not be useful and expose many to unnecessary investigations and treatments.