DNA differences between men and women may explain why cancer risk is higher in males according to a new study. In findings published in the Journal of the National Cancer Institute researchers have reported that loss of function in certain genes of the sex-determining Y chromosome which is present only in men may cause them to have an elevated risk for cancer. Using data from 9000 individuals the researchers studied gene function in patients with various types of cancer. The findings showed that cancer risk increases with loss of function of six key Y-chromosome genes in various types of cells.