The purpose of this nationwide, population register-based study was to describe variations in cancer incidence and survival by social position in a social welfare state, Denmark, on the basis of a range of socioeconomic, demographic and health-related indicators. Our study population comprised all 3.22 million Danish residents born in 1925-1973 and aged >or=30 years, who were followed up for cancer incidence in 1994-2003 and for survival in 1994-2006, yielding 147,973 cancers. The incidence increased with lower education and income, especially for tobacco- and other lifestyle-related cancers, although for cancers of the breast and prostate and malignant melanoma the association was inverse. Conversely there was a general increase in incidence among early retirement pensioners, persons living in rented housing and those living in the smallest dwellings. Also incidence rates were generally higher in persons living alone compared to those living with a partner and in the capital area compared to the rural areas. Social inequality in the prognosis of most cancers was observed, despite the equal access to health care in Denmark, with poorer relative survival related to fewer advantages, regardless of how they were measured, often most pronounced in the first year after diagnosis. Also living alone and having somatic or psychiatric comorbidity negatively impacted the relative survival after most cancers. Our study shows that inequalities in cancer incidence and survival must be addressed in all aspects of public health, with interventions both to reduce incidence and to prolong survival.