Cancer incidence in Eastern Adriatic isolates, Croatia: Examples from the islands of Krk, Cres, Losinj, Rab and Pag

As an extension of previous research this study investigates the incidence of cancer in five genetic isolate island populations of the Eastern Adriati c, Croatia. Thorough anthropological research over the past three decades h as established some of those populations as outstanding examples of genetic isolates. A previous study which found higher cancer incidence in 5 Easter n Adriatic islands than in a control population supported a hypothesis that among the founders of these populations there were genetic variants (espec ially with recessive inheritance) responsible for genetic susceptibility to certain types of cancer. This study sought to investigate cancer incidence in 5 further island populations. All cancer cases in five island populatio ns (Krk, Cres, Losinj, Rab and Pag) over the 20-year period (1971 to 1990) was extracted from the data of the Croatian Cancer Registry. The mainland p opulations of Istrian and Primorsho-Goranska County, characterized by simil ar environmental factors but an outbred genetic structure, represented a co ntrol population. After standardization by by sex and age, cancer incidence teas higher in the island populations than in the control population in bo th sexes. The cancer sites primarily responsible for the excess incidence w ere prostate, stomach and pancreatic cancer in males, and ovarian, breast, stomach, bowel, and brain cancer in females. The reasons for the increased cancer incidence are uncertain and may be due to different environmental ex posure between the two populations. However it is possible that genetic iso lation and inbreeding are important factors. Further investigations of canc er in these isolate populations are warranted to explore these findings fur ther.