http://story.news.yahoo.com/news?tmpl=story&u=/usatoday/20021023/en_usatoday/4557351

Anita Manning USA TODAY

Vaccine safety experts reported Tuesday that they could not say whether contaminated polio (news web sites) vaccine given decades ago to millions of Americans caused cancer later in life.

The committee, which reviewed reams of data on the possible link between polio vaccine tainted with a monkey virus and the occurrence of certain rare cancers, said lab experiments show the virus has cancercausing properties, but there has been no increase in cancer among people who got the vaccine. Concluding the information was ''inadequate,'' it called for more research, a national plan to prevent vaccine contamination and a quick response if it happens again.

Between 1955 and 1963, about a third of the 98 million people who got polio shots received vaccine containing SV40, a monkey virus used during production.

Studies have found that SV40 causes cancer in lab experiments. It also has been detected in some types of tumors, suggesting a link between the vaccine and rare brain and bone cancers, mesotheliomas, which are tumors of the lung lining, and nonHodgkin's lymphoma.

The report from a committee of the Institute of Medicine (news web sites), which provides health policy information to the government, says there is no evidence the virus caused those tumors and no increase in cancer among those likely to have received the questionable vaccine.

''Having the virus in the tumor does not mean it caused the tumor,'' says committee member Steven Goodman of Johns Hopkins University Medical School.

No one knows who got tainted vaccine, and the tumors associated with it are so rare that the committee felt it didn't have enough solid information to make a definitive conclusion, said committee chair Marie McCormick of the Harvard School of Public Health.

People who fear they got contaminated vaccine do not need to take protective steps, Goodman says. ''There is nothing to be done about detection or avoidance of these cancers, so there's no substantive action doctors or patients could take, even if they chose to be worried about this . . . hypothetical risk,'' he says.

The report recommends development of blood tests for the virus and studies of pre1955 tissue samples to see if there was SV40 infection prior to the vaccine. It also calls for research to confirm studies that found evidence of SV40 in tumors from patients too young to have gotten tainted vaccine and to determine possible transmission routes.

''There's every reason to think that the virus is now established within the human population,'' says researcher Janet Butel of Baylor College of Medicine in Houston, who was not on the committee. ''I think the vaccine used before 1963 seeded SV40 in the population, and it's causing human infection today, but we don't know who is infected or how the virus is being transmitted.''