Weight change and cancer

Abstract

<p><i>Background: </i>The obesity prevalence has reached pandemic dimensions. The cancer incidence has also increased worldwide, and several cancers are related to body fatness. However, there are uncertainties weather the velocity and magnitude of weight gain, independent of body fatness, increase cancer risk. Moreover, there are few studies on short-term weight gain and site-specific cancers. Thus, our aim was to study weight change over 6–7 years in relation to all and specific body fatness-related cancers in women in Norway. <p><i>Methods: </i>We used Cox proportional hazard models and restricted cubic splines to assess weight change and subsequent cancer incidence, in the Norwegian Women and Cancer Study. Further, we calculated population attributable fractions to assess the impact of weight gain on the body fatness-related cancer burden. <p><i>Results: </i>Short-term weight gain, independent of body weight status, was associated with increased risk of all body fatness-related cancers combined, and several site-specific cancers, in a non-linear dose-response manner. Women who gained more than 10kg had a two-fold increased risk of pancreatic cancer. Moreover, stable weight could have prevented 43% of pancreatic cancers cases in women in Norway diagnosed in 1998–2015, as well as 4299 postmenopausal breast cancer cases and 2798 colorectal cancer cases. <p><i>Conclusions: </i>Avoiding weight gain has important implications for public health interventions, as several cancers seem to be preventable through weight maintenance. Our results on pancreatic cancer are novel and of upmost importance given the poor prognosis of the disease and increased rate in women, both in Norway and worldwide.