Use of surveillance systems for occupational cancer: data from the Danish National system

In Denmark the 1970-census population has been followed up for deaths, emigrations, and cancer cases during the ten-year period 1970-80. The linked register allows tabulation of cancer incidence by occupation, however no information is available on specific exposures. It is therefore an indication of the validity of the register that classic associations known from in-depth epidemiological studies are found also in the register. Examples are cancer of the lip in farmers, RR = 1.85, and fishermen, RR = 3.17; and cancer of the nasal cavities and sinuses in skilled furniture makers, RR = 12.25. The register may serve as a library for further elucidation of newly reported associations. Examples, of such associations confirmed in the Danish data, are an excess risk of colon cancer among males with sedentary work, RR = 1.38; and an excess risk of bladder cancer in hairdressers, RR = 2.05. An unconfirmed example is an excess risk of malignant melanoma in the printing industry, where the Danish data show an RR of 0.95. A systematic tabulation of each cancer diagnosis across detailed occupational groups may lead to identification of previously unknown associations. This procedure is illustrated using cancer of the pharynx as an example. Painters were identified as having an excess risk of pharyngeal cancer (RR = 2.27, 95% CI 1.1-4.2).