Background Age is the strongest risk factor for developing cancer. The aim of the present analysis is to give an overview of the trends in cancer incidence, mortality, prevalence, and relative survival in Denmark from 1980 to 2012 focusing on age, comparing persons aged 70 years or more with those aged less than 70 years. Material and methods Data derived from the NORDCAN database with comparable data on cancer incidence, mortality, prevalence and relative survival in the Nordic countries. The Danish data originate from the Danish Cancer Registry and the Danish Cause of Death Registry with follow-up for death or emigration until the end of 2013. Results Incidence and mortality rates of all sites, but non-melanoma skin cancer, were higher and relative survival was lower among persons aged 70 years or more than those aged less than 70 years. The age distribution (age group-specific percentages of total number of incident cases) remained constant over time while the percentage of persons dying from cancer decreased with time up to the age of 79 years but increased for those aged 80 years or more, in whom about a third of all cancer deaths occurred in 2012. In 2003-2007, the five-year relative survival was 48% for men aged 70-79 years, 38% for men aged 80-89 years, and 29% for men aged 90 years or more and the corresponding figures for women were 46%, 39%, and 36%, respectively. There was a substantial increase in the number of prevalent cancer cases aged 70 years or older, especially among those aged 90 years or more. Conclusion An increase in elderly cancer patients is expected over the coming 20 years due to an increasing elderly population. Healthcare providers need to focus on developing specific strategies for treatment of elderly cancer patients in the future.