Abstract Background: Added sugars’ deleterious effects have been established for several chronic diseases, leading food industries to use artificial sweeteners as alternatives in a wide range of foods and beverages. Their safety is debated and findings remain contrasted regarding their role in the etiology of various diseases. In particular, their carcinogenicity has been suggested by several experimental studies but robust epidemiological evidence is lacking. Objective: The objective was to investigate the associations between sweetener intakes (total from all dietary sources, and most frequently consumed ones: aspartame e951, acesulfame-K e950 and sucralose e955) and cancer risk (overall and by sites: breast, prostate and obesity-related cancers). Design: Population based prospective cohort study. Setting and Participants: Overall, 102,046 adults from the French NutriNet-Santé prospective cohort (2009-2021) were included. Consumption of sweeteners was obtained by repeated 24h-dietary records including brands and commercial names of industrial products. Associations between sweeteners and cancer incidence were assessed by multi-adjusted Cox hazard models. Main outcome measures: Association between sweetener intakes and cancer risk were assessed by Cox proportional hazard models adjusted for known risk factors (sociodemographic, anthropometric, lifestyle, medical history, and nutritional factors). Results: Compared to non-consumers, higher consumers of total sweeteners (i.e. above the median exposure in consumers) had higher risk of overall cancer (n=2,527 cases, hazard ratio=1.12, 95% confidence interval=1.00-1.25, P-trend=0.005). In particular, aspartame (HR=1.20 [1.05-1.38] P=0.001) and acesulfame-K (HR=1.18 [1.04-1.34] P=0.003) were associated with increased cancer risk. Similarly, higher risks were observed for breast (n=723 cases, HR=1.25 [1.02-1.53] P=0.01 for total sweeteners, HR=1.33 [1.05-1.69] P=0.007 for aspartame and HR=1.39 [1.11-1.74] P=0.003, for acesulfame-K) and obesity-related cancers. (n=1,509 cases, HR=1.16 [1.00-1.33] P=0.02 for total sweeteners, HR=1.22 [1.02-1.45] P=0.01 for aspartame and HR=1.23 [1.04-1.45] P=0.01, for acesulfame-K). Conclusion: In this large prospective cohort, artificial sweeteners (especially aspartame and acesulfame-K), which are found in >10,000 foods and beverage references worldwide, were associated with increased cancer risk. These findings provide important and novel insights for the ongoing re-evaluation of food additive sweeteners by the European Food Safety Authority and other health agencies globally. Citation Format: Charlotte Debras, Eloi Chazelas, Bernard Srour, Nathalie Druesne-Pecollo, Younes Essedik, Fabien Szabo de Edelenyi, Cédric Agaësse, Alexandre De Sa, Rebecca Lutchia, Stéphane Gigandet, Inge Huybrechts, Chantal Julia, Emmanuelle Kesse-Guyot, Laurent Zelek, Benjamin Allès, Valentina A. Andreeva, Pilar Galan, Serge Hercberg, Mélanie Deschasaux-Tanguy, Mathilde Touvier. Risk of breast and other cancers associated with the consumption of artificial sweeteners: Results from the prospective NutriNet-Santé cohort [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-09-02.