High consumption of ultra-processed food and risk of colorectal cancer: the Norwegian Women and Cancer cohort study.

Norway exhibits one of the highest rates of colorectal cancer (CRC) in the world, and several dietary factors have been associated with the risk of CRC. With higher consumption of ultra-processed foods (UPF), a better understanding of how food processing affects CRC might be a new approach for prevention. The current findings are contradictory, and new findings indicate that CRC risk factors might affect colorectal subsites differently. We wanted to study the association between intake of UPF and CRC risk in Norwegian women. In this prospective cohort analysis encompassing 77 100 women (1625 cases) from the Norwegian Women and Cancer study, dietary intakes were collected using validated semi-quantitative FFQ and categorised using the Nova classification system. Multivariable Cox proportional hazard models were used to assess the association between intake of UPF and CRC risk. The average follow-up time was 17·4 years. A high UPF intake (fourth quartile), compared with a low UPF intake (first quartile), was statistically significantly associated with increased total CRC risk after adjusting for all covariates and energy intake (hazard ratio (HR) = 1·24; 95 % CI 1·04, 1·49, P_{for trend} = 0·02). Furthermore, a high UPF intake, compared with a low UPF intake, was statistically significantly associated with right-sided colon cancer (HR = 1·58; 95 % CI 1·19, 2·09, P_{for trend} < 0·001). More research is needed to understand the associations between UPF, UPF subgroups and total CRC as well as cancer in colorectal subsites.