Summary We have examined the incidence of non-AIDS-related Kaposi's sarcoma in Iceland and the Faroe Islands . In Iceland, 19 cases, nine in men and ten in women, were identified, and in the Faroe Islands four cases in men and three cases in women were found. This corresponded to surprisingly high incidence rates. In men, world standardized rates (per 100 000 person-years) were 0.4 and 0.6 in Iceland and the Faroe Islands, respectively, and for women, the figures were 0.3 (Iceland) and 0.5 (the Faroe Islands). These are among the highest rates ever reported. No explanation for the high rates of Kaposi's sarcoma in these two North Atlantic communities could be identified.Keywords: Kaposi's sarcoma; Iceland, Faroe Islands; epidemiology From an increasing number of epidemiological studies it has become evident that the incidence of classical Kaposi's sarcoma (KS) differs considerably between Caucasian populations. Accordingly, within Europe alone, reported annual rates per 100 000 persons have varied from 2.43 and 0.77 in Sardinian men and women, respectively, in the period 1977-91, to 0.014 in both men and women in the UK in the period (Grulich et al, 1992;Cottoni et al, 1996).The pronounced geographical gradient in incidence of classical KS in Europe, with high rates observed in the Mediterranean area and low rates in northern areas, is in accordance with other studies suggesting a disproportionately high number of persons of southEuropean descent among patients with classical KS even in nonMediterranean countries (DiGiovanna and Safai, 1981;Grulich et al, 1992;Kaldor et al, 1994;Hjalgrim et al, 1996a). However, in a recent study of classical KS in four Nordic countries (Sweden, Norway, Finland and Denmark) before the AIDS epidemic, we reported that highly significant variation in incidence amounting to eightfold in women and 13-fold in men may also exist between four ethnically very similar, neighbouring populations (Hjalgrim et al, 1996b). As this variation could not be attributed to any known risk factor for classical KS, including proportion of immigrants from high-risk areas, transplantations, diagnostic or registrational procedures, it may suggest the existence of an environmental factor of significance for the development of KS (Hjalgrim et al, 1996b).Intrigued by the variation in KS incidence between these four countries, we ascertained the incidence of classical KS in two other geographically distinct Nordic populations, Iceland and the
MATERIAL AND METHODS Case-ascertainment proceduresThe Icelandic Cancer Registry has registered KS separately since its establishment in 1955. For the purpose of the present study, all reports of KS in the registry in the period until 1979 were identified, and the original histological specimens were reviewed by one of us (SH) to confirm the diagnosis. The limitation of the study period was applied to avoid misclassification of cases of AIDSrelated KS, because AIDS diagnoses are not recorded by the registry. Although attempts have been made to initiate continuous canc...