A STUDY of 90 000 twins has underlined the overwhelming importance of
environmental factors in deciding who gets cancer. The Swedish survey shows that
smoking, diet, exposure to chemicals and infection are far more important causes
of cancer than inherited genetic defects.
Paul Lichtenstein and colleagues at the Karolinska Institute in Stockholm
looked at the likelihood of both members of a pair of twins contracting
particular cancers. In the biggest ever study of its kind they examined the
medical records of 45 000 pairs of twins from archives in Sweden, Denmark and
Finland over the past century.
Overall, the study…
