CANCER RISK IN FISHERMAN FAMILIES: A RETROSPECTIVE COHORT STUDY IN FINLAND

Abstract

ISEE-193 Introduction: Fish and fish products are nutritionally important and beneficial to human health. Their omega-3 fatty acids may prevent some cancers, including cancers of the breast, prostate and colon. However, some fish species may also contain high levels of environmental pollutants such as dioxins and methyl mercury. Aim: The overall effect of fish on cancer risk can best be assessed in populations, which include persons with high fish intakes. This study investigates cancer risk in professional fishermen and their families. Methods: The study cohort holds 6,927 professional fishermen who were identified as professional fishermen in 1980 or later, based on the files of professional fishermen kept by the Ministry of Agriculture and Forestry. The study cohort also includes fishermen’s family members (defined as spouses and children of the index person, and as spouses and children of the index person’s siblings) identified from the Central Population Register. Linkage to the Finnish Cancer Registry provided data on 1,060 incident cancer cases among the whole study cohort (36,097 people). Calculation of person-years (418,000 person-years in the whole cohort) began at time of registration of the fisherman or time of marriage (if later, in cases of being a spouse), and ended at death or 31 December 2002. The observed numbers of cases and person-years at risk were calculated by age (five year age groups), sex, and calendar period. The expected numbers of cases were calculated by multiplying the specific number of person-years for the category by the corresponding incidence of cancer in Finland. The standardised incidence ratios (SIR) were calculated by dividing the observed number of cases by the number expected. Results: We found a SIR of 0.94 (95% CI = 0.89–1.00) for total cancer in the entire cohort. The risk of most cancer types in fishermen and their family members was close to the general population risk. Contrary to the occupational studies on dioxins and cancer, the risk for lung cancer among the fishermen was decreased (SIR = 0.77, 95% CI = 0.60– 0.96). The SIR for haematological cancers was increased in fishermen (1.33, 1.00 – 1.72) and their siblings (1.44, 0.92 – 3.54), but not in fishermen’s spouses or in siblings’ spouses. Conclusion: Overall, the risk of cancer in fisherman families was close to the general population risk. The prevalence of cancer risk factors in this cohort is poorly known. Assessments of dietary intakes and life-styles, and measurements of environmental contaminants in biological specimens are ongoing and will provide further information on health effects of fish.