To examine the role of gender, age at immigration and length of stay on incidence trends of common cancers, we studied risk of colorectal, lung, breast and prostate cancers in immigrants to Sweden from 1958 to 2008. The nationwide Swedish Family-Cancer Database was used to calculate standardized incidence ratios for common cancers among immigrants compared to Swedes. Immigrants were classified into "high-risk" countries when their risk was increased, into "low-risk" when their risk was decreased and into "other" when their risk was nonsignificant. Among those who immigrated at younger age (