Early life residence, fish consumption and risk of breast cancer
Menée en Islande à partir de données portant notamment sur le premier lieu de résidence (village côtier, village rural, ville) de 9 340 femmes nées entre 1908 et 1935 et à partir de questionnaires auprès d'un sous-groupe incluant 2 882 participantes (durée médiane de suivi : 27,3 ans), cette étude évalue l'association entre la quantité de poisson consommée à différentes périodes de l'existence et le risque de cancer du sein (744 cas)
Background : Little is known about fish intake throughout the life course and the risk of breast cancer. Methods : We used data on the first residence of 9,340 women born 1908-1935 in the Reykjavik Study as well as food frequency data for different periods of life from a subgroup of the cohort entering the AGES-Reykjavik Study (n = 2,882). Results : During a mean follow-up of 27.3 years, 744 women were diagnosed with breast cancer in the Reykjavik Study. An inverse association of breast cancer was observed among women who lived through the puberty period in coastal villages, compared with women residing in the capital area (HR = 0.78, 95% CI: 0.61, 0.99). In the subgroup analysis of this Icelandic population, generally characterized by high fish intake, we found an indication of lower risk of breast cancer among women with high fish consumption (more than 4 portions per week) in adolescence (HR 0.71, 95% CI, 0.44, 1.13) and midlife (HR 0.46, 95% CI, 0.22, 0.97), compared with low consumers (2 portions per week or less). No association was found for fish liver oil consumption in any time period which could be due to lack of a reference group with low omega-3 fatty acids intake in the study group. Conclusion : Our findings suggest that very high fish consumption in early to midlife may be associated with a reduced risk of breast cancer. Impact : Very high fish consumption in early adulthood to midlife may be associated with decreased risk of breast cancer.