TORONTO - A new study says protecting women aged 17 to 26 against the human papillomavirus or HPV in a catch-up vaccination round would save lives -- and save millions of dollars in the process.

The study suggests the strategy would save nearly $19 million a year and lead to a reduction in cervical cancers that would save 240 years of life annually.

The 240 figure means the number of extra years a number of women would live because they didn't contract and die from cervical cancer.

Senior author Chris Bauch led the modelling study, which looked at whether it makes sense economically to vaccinate young women in Ontario who missed out on the publicly funded HPV vaccine program.

Ontario has been making the HPV vaccine available for free to girls in Grade 8 since its program was launched in 2007.

Bauch works in the department of mathematics and statistics at the University of Guelph, in Ontario; his paper was published in the journal Vaccine.

He and colleagues used a mathematical model to look at the economic impact and cancer incidence impact of a catch-up round for Ontario teens and young women aged 17 to 26.

They proposed that the catch-up round could be done in conjunction with another policy change -- delaying the recommended time for women's first cervical cancer screening appointments to age 25.

Currently it is recommended that women have their first Pap smear, as the test is called, at age 18 and have a second a year later. If both show no signs of abnormal cells, it's recommended they return for screening every three years.

Delaying the start of that process would save money and wouldn't jeopardize lives overall, the study suggested. Cervical cancers mostly develop in middle age.

"Basically you're stopping a program that doesn't prevent a lot of cancer, a) because there isn't a lot of cancer in younger ages and b) because the screening is actually not very exact," Bauch said.

"And you're taking the money you save on that relatively inefficient program and putting it into the vaccine, which can prevent more cancer more effectively than the screening program, according to the model."

The study was based on the premise the vaccine used in the older women would be a different one than that used in the high school program.

Ontario uses a vaccine called Gardasil, which is made by pharmaceutical giant Merck. It protects against four strains of HPV, the ones responsible for most cases of cervical cancer.

The model looked at use of vaccine called Cervarix in the older women. Made by GlaxoSmithKline, Cervarix only protects against two strains of the virus. But it's made with an adjuvant, a compound that amps up the immune system's response to the vaccine. It appears that this HPV vaccine may be more effective in older women, Bauch said.

A portion of the funding for the study -- 15 per cent -- came from GSK, and one of Bauch's co-authors worked for the drug company at the time of the writing of the paper.

Bauch studied only Ontario data, so cannot say whether other provinces would also experience savings from following this approach. But he said given the similarities between provincial programs in terms of the cost of the vaccine and its efficacy, he would expect what the model found for Ontario might also hold true elsewhere.

He said there is a side-effect that public health officials would need to consider if they were to make the change. Physicians often use the first cervical cancer screening appointment to offer young women other health services -- things like discussing birth control, for instance.

If it was recommended that women receive their first Pap smear at age 25, doctors would need to find another opportunity to offer those services to women in their late teens, Bauch said.