Cancer

All of the Nordic countries have population-based cancer registries and all the countries except for Sweden have centralised coding and classification. The Danish Cancer Registry is the oldest and was founded in 1942. A decade later, in 1952-1954, the Norwegian, Finnish and Icelandic cancer registries were established. The Swedish cancer registry was founded in 1958. Data from the national registries is used for research and administrative and political purposes. It is also to some extent accessible to media and to the public.

Both external and internal factors that produce changes in the DNA material can cause cancer. Stimulants, foodstuffs, exposure to some occupational hazards and factors in the environment have been shown to be cancer inducing. The incidence of cancer also increases with age. On a more positive note, however, it is estimated that around 40 per cent of cancer incidents can be avoided through healthier lifestyle choices, the main factors being tobacco, alcohol and overweight. Furthermore, steps can be taken in working environments to avoid exposure to cancer causing elements.

The development of cancer diseases in the Nordic countries remains analogous for most forms of cancer, but there are interesting differences. In general, the number of persons diagnosed with cancer has increased with time, with a few exceptions of decreasing incidence such as for stomach cancer. In the Nordic countries, the decrease in the incidence of cervix cancer, is related to the public screening programmes to detect pre-cancerous lesions and early lesions, and the ensuing treatment.

The screening is conducted every three or five years. Denmark, Iceland and Sweden start the screening at age 23, the Faroe Islands and Norway at age 25 and Finland at age 30. The upper age limit varies from age 60 in the Faroe Islands and Finland to age 69 in Norway. In the future the HPV vaccination programmes will make the screening of cervix cancer less relevant for young women. However, the screening will remain relevant because a share of the populations has not received the vaccine, and since not all cancers of the cervix are caused by the HPV.

The incidence of breast cancer and colorectal cancer is increasing in almost all countries. Dietary factors are probably significant for this development, but for breast and prostate cancer, hormonal factors play the most important role. All Nordic countries excluding Greenland have a breast cancer screening programme. In Denmark, the Faroe Islands, Finland and Norway, screenings are conducted on women aged 50-69 every two years. The age groups are wider in Iceland (age 40-69) and Sweden (age 40-74). There has been debates over the cost-effectiveness of breast cancer screenings in recent years. A meta-analysis from 2016 stated that breast cancer mortality is generally reduced with mammography screening, although estimates are not statistically significant at all ages and the size of the effects are small. With screenings for women aged 50 years or older, the rate of advanced stages of cancer is reduced[1].

Denmark has a national screening programme for colon and rectum cancer, and there are similar regional pilot projects in Finland and Norway.

Except for Finland, the incidence of testis cancer is stagnating in most of the countries. The incidence of tobacco-related cancers, such as lung cancer, is high in all the countries. However, the incidence of lung cancer among men is decreasing. None of the Nordic countries have screening programmes for lung or testicular cancer.

[1] Nelson HD, Fu R, Cantor A, Pappas M, Daeges M, Humphrey L. Effectiveness of Breast Cancer Screening: Systematic Review and Meta-analysis to Update the 2009 U.S. Preventive Services Task Force Recommendation. Ann Intern Med. 2016 Feb 16;164(4):244-255.