Pre- and post-diagnostic dairy intake in relation to recurrence and all-cause mortality in people with stage I-III colorectal cancer

PURPOSE: Higher dairy consumption is associated with a lower risk of colorectal cancer (CRC), but no studies thus far have investigated its relation with recurrence in CRC. Few studies have investigated total dairy in relation to mortality in CRC, and yielded inconsistent results. METHODS: In this prospective cohort study, people newly diagnosed with stage I-III CRC filled out a food frequency questionnaire at diagnosis (n = 1812) and six months after diagnosis (n = 1672). We examined associations between pre- and post-diagnostic intake of total dairy, low-fat dairy, high-fat dairy, milk, yoghurt, and cheese with recurrence and all-cause mortality using multivariable Cox proportional hazard models and restricted cubic splines (RCS). RESULTS: A total of 176 recurrences and 301 deaths occurred during a median follow-up of 3.0 and 5.9 years, respectively. Before diagnosis, a higher low-fat dairy intake was associated with a lower risk of recurrence (HR(Q4vsQ1): 0.42, 95% CI 0.26–0.67; P(RCS): 0.008) and all-cause mortality (HR(Q4vsQ1): 0.58, 95% CI 0.41–0.81; P(RCS) < 0.001), whereas a higher high-fat dairy consumption tended to be associated with an increased all-cause mortality risk (HR(Q4vsQ1): 1.41, 95% CI 0.98–2.01; P(RCS): 0.030). After diagnosis, only the associations between low- and high-fat dairy in relation to all-cause mortality remained. CONCLUSIONS: This study demonstrated that higher pre- and post-diagnostic intakes of low-fat dairy were associated with a reduced all-cause mortality risk in people with stage I-III CRC, whereas higher intakes of high-fat dairy were associated with an increased all-cause mortality risk. Also, a higher pre-diagnostic low-fat dairy intake was associated with a reduced risk of recurrence. TRIAL REGISTRATION: Clinical Trials.gov identifier: NCT03191110. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00394-023-03201-0.