Abstract B068: Post-diagnostic dietary fat intake and long-term survival among patients with stage T1-T3 prostate cancer

Abstract Introduction: There are 3. 5 million prostate cancer survivors in the United States. While prostate cancer is the second leading cause of cancer death in men, individuals with prostate cancer have a higher risk of dying of cardiovascular diseases or other cancers than prostate cancer. The composition of dietary fats plays a key role in mortality as saturated and trans fats, and fats from animal sources, are associated with an increased risk of all-cause and cardiovascular mortality in the general population. This highlights the need for evidence-based recommendations for lifestyle interventions that improve survival overall among prostate cancer patients. Methods: We investigated dietary fat intake and mortality among 4, 884 men diagnosed with clinical stage T1-T3 prostate cancer between 1986 and 2019 who were participants of the Health Professionals Follow-up Study. Dietary data collected every 4 years using validated semi-quantitative food frequency questionnaires (FFQ) were used to assess post-diagnosis intakes of saturated, polyunsaturated, monounsaturated, and trans fats, as well as fats from animal or vegetable sources. Post-diagnosis dietary fat intake was defined as the intake reported on the first questionnaire with FFQ collected at least 6 months after diagnosis. Multivariable Cox regression and nutrient-density models were used to investigate associations between dietary fat intake (in quintiles) after diagnosis and all-cause, prostate cancer, other cancer, and cardiovascular mortality through 2022. Results: The median age at prostate cancer diagnosis was 70 years (IQR 65-74). The primary causes of death were due to prostate cancer (441 deaths), other cancers (499 deaths), and cardiovascular disease (803 deaths). Higher post-diagnostic saturated fat intake was associated with higher risk of all-cause mortality (HRQ5vQ1 1. 28, 95% CI 1. 10-1. 50), cardiovascular mortality (HRQ5vQ1 1. 45, 95% CI 1. 06-1. 98), and death from other cancers (HRQ5vQ1 1. 46, 95% CI 0. 98-2. 18). Replacing 10% of calories from animal fats with carbohydrates (HR 0. 91, 95% CI 0. 83-1. 00) or vegetable sources (HR 0. 85, 95% CI 0. 77-0. 93) was associated with a lower risk of all-cause mortality. Replacing 5% of calories from saturated fat with monounsaturated fat was also associated with a lower risk of all-cause mortality (HR 0. 80, 95% CI 0. 71-0. 91), primarily due to reductions in cardiovascular mortality. There were no associations between any fat intake and prostate cancer mortality in any models when comparing extreme quintiles of intake. Conclusion: Among participants with non-metastatic prostate cancer, higher intake of post-diagnostic saturated fat was associated with higher risk of all-cause mortality, driven by death from cardiovascular disease and other cancers, the primary causes of mortality in this patient group. Our results suggest that replacing saturated and animal fats with healthier plant fats may improve survival among prostate cancer patients. * YZ, MRS: Authors contributed equally ** ELG, DPL, LAM: Senior authors contributed equally Citation Format: Megan R. Shanahan, Yiwen Zhang, Hannah E. Guard, Jiachen Ji, Maria Celia Fernandez, Nadia Boufaied, Jane B. Vaselkiv, Binkai Liu, Chaoran Ma, Rebecca E. Graff, Stacy Loeb, Caroline Himbert, Yuan Ma, Edward L. Giovannucci, David P. Labbé, Lorelei A. Mucci. Post-diagnostic dietary fat intake and long-term survival among patients with stage T1-T3 prostate cancer abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Prostate Cancer Research and Treatment; 2026 Jan 20-22; Philadelphia PA. Philadelphia (PA): AACR; Cancer Res 2026;86 (2Suppl): Abstract nr B068.