Adulthood overweight and survival from breast and colorectal cancer in Swedish women
Menée en Suède à partir de données portant sur 47 051 participantes, cette étude de cohorte analyse l'association entre l'évolution de l'indice de masse corporelle entre l'âge de 20 et 50 ans et la survie, chez des patientes ayant survécu à un cancer colorectal (259 cas ; âge médian au diagnostic : 59,1 ans) ou à un cancer du sein (1 241 cas ; âge médian au diagnostic : 57,5 ans)
Background: The impact of overweight duration and intensity during adulthood on the prognosis after a cancer diagnosis remains largely unknown. We investigated this association in Swedish women with breast and colorectal cancer. Methods: A cohort of 47,051 women from the Swedish Lifestyle and Health Study were included, of whom 1,241 developed postmenopausal breast (mean age at diagnosis: 57.5 years) and 259 colorectal cancer (mean age at diagnosis: 59.1 years). Trajectories of body mass index (BMI) between ages 20 and 50 were estimated for the full cohort using a quadratic growth model and studied in relation to risk of death from any cause using multivariate Cox regression models among cancer survivors. Results: Compared with cancer patients who were never overweight (BMI<25) during early adulthood (ages 20-50), the risk of early death from breast cancer increased by 3% (HR=1.03, 95%CI= 1.01-1.05) and from colorectal cancer by 4% (HR=1.04, 95%CI=1.01-1.06) for every year lived with overweight. A higher intensity of overweight (i.e., a combination of duration and degree of overweight - a concept comparable to pack-years of cigarette smoking) further increased the risk of dying in this population. While risks were slightly more pronounced for women diagnosed with late-stage breast cancer, no clear association was found for colorectal cancer. Conclusions: Our results suggest that adulthood overweight duration and intensity have a long‐lasting influence on breast and colorectal cancer survival. Impact: Our study highlights the need for effective prevention of overweight and obesity starting at an early age.