Introduction

Traditionally, maps on the occurrence of cancer have been based on large administrative units. However, sometimes marked variation exists within such larger units, because the patterns of aetiological factors do not necessarily follow the administrative borders. The project of producing a small-area based atlas of cancer incidence and mortality in Northern Europe was introduced at a conference in Stockholm entitled Epidemiology around the Baltic Sea (October 1992) with participants from all countries around the Baltic Sea. Later on, Norway, Iceland and Belarus agreed to join the project, and thereby practically the whole Northern Europe was covered.

The number of inhabitants living in the 7,145 cities and rural municipalities used as basic units of
data collection of this Atlas exceeds 200 million. Almost 380,000 persons die from cancer every
year, and the number of new cancer cases diagnosed annually can be estimated  to be close to 570,000. The actual number of incident cancer cases included in the maps of this Atlas is 2.0 million and the number of cancer deaths 3.5 million. These numbers do not only form a statistically sound basis for reliable map presentation but they also directly indicate that cancer is a very common group of diseases which deserves full attention. This Atlas is an easy way to illustrate variation in cancer frequencies. All these international geographical patterns - and many of the national ones - are now published for the first time ever.