A study from Denmark suggests that polio vaccine contaminated with the SV40 virus is not linked to increased rates of cancer.

In the 1950s and 1960s there was widespread exposure to polio virus contaminated with a virus called SV (simian virus) 40. Studies have linked SV40 to a number of cancers in rodents. DNA from SV40 has also been found in a wide range of human tumors, such as leukemia and testicular carcinoma. So naturally there is concern as to whether exposure to SV40 contaminated vaccine could increase rates of human cancer.

Researchers for the National Cancer Institute in Denmark examined cancer rates from 1943 to 1997 in groups who had, and had not, been exposed to contaminated vaccine. They found no difference in the cancer rates. This seems reassuring but the researchers recommend further investigation. For the evidence is conflicting, given previous studies and the matter remains one of public health concern, given the widespread exposure to the contaminated polio vaccine.

Source

Journal of the National Cancer Institute 2nd April 2003