A survey of cancer incidence data suggests that polio vaccine is not linked to the occurrence of a rare tumour.

During the mass immunization against polio in the 1950s and 1960s, batches of vaccine were used that were found the be contaminated with a monkey virus called SV40. Because SV40 causes tumours in rodents, when injected at high levels, and has also turned up in human tumours, there have been fears that the polio vaccine might lead to cancer in later years.

In particular, SV40-contaminated polio vaccine has been implicated in the development of a rare cancer called pleural mesothelioma, which affects the lining of the lungs and chest. Researchers in New York have analysed the increase in mesothelioma between 1975 and 1997. They conclude that most of the increase is among men over 75 - the group least likely to be exposed to polio vaccine. Among those young enough to have been in the polio vaccine programme, the rates were, if anything, lower than before. So, 40 years on, there is no evidence that polio vaccine contaminated with SV40 increases the risk of cancer. But it still worthwhile continuing to keep this matter under review, say the researchers.

Source

Journal of the National Cancer Institute 1st January 2003