Michèle Matta 1, Inge Huybrechts 1, Carine Biessy 1, Corinne Casagrande 1, Sahar Yammine 1, Agnès Fournier 2 3, Karina Standahl Olsen 4, Marco Lukic 4, Inger Torhild Gram 4, Eva Ardanaz 5 6 7, Maria-José Sánchez 7 8 9 10, Laure Dossus 1, Renée T Fortner 11, Bernard Srour 11, Franziska Jannasch 12 13 14, Matthias B Schulze 12, Pilar Amiano 7 15, Antonio Agudo 16, Sandra Colorado-Yohar 7 17 18, J Ramón Quirós 19, Rosario Tumino 20, Salvatore Panico 21, Giovanna Masala 22, Valeria Pala 23, Carlotta Sacerdote 24, Anne Tjønneland 25 26, Anja Olsen 25 27, Christina C Dahm 27, Ann H Rosendahl 28, Signe Borgquist 28 29, Maria Wennberg 30, Alicia K Heath 31, Dagfinn Aune 31 32 33, Julie Schmidt 34, Elisabete Weiderpass 35, Veronique Chajes 1, Marc J Gunter 1, Neil Murphy 36
BMC Med. 2021 Mar 30;19(1):81. doi: 10.1186/s12916-021-01952-3.
Background: Trans fatty acids (TFAs) have been hypothesised to influence breast cancer risk. However, relatively few prospective studies have examined this relationship, and well-powered analyses according to hormone receptor-defined molecular subtypes, menopausal status, and body size have rarely been conducted.
Methods: In the European Prospective Investigation into Cancer and Nutrition (EPIC), we investigated the associations between dietary intakes of TFAs (industrial trans fatty acids [ITFAs] and ruminant trans fatty acids [RTFAs]) and breast cancer risk among 318,607 women. Multivariable hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models, adjusted for other breast cancer risk factors.
Results: After a median follow-up of 8.1 years, 13,241 breast cancer cases occurred. In the multivariable-adjusted model, higher total ITFA intake was associated with elevated breast cancer risk (HR for highest vs lowest quintile, 1.14, 95% CI 1.06-1.23; P trend = 0.001). A similar positive association was found between intake of elaidic acid, the predominant ITFA, and breast cancer risk (HR for highest vs lowest quintile, 1.14, 95% CI 1.06-1.23; P trend = 0.001). Intake of total RTFAs was also associated with higher breast cancer risk (HR for highest vs lowest quintile, 1.09, 95% CI 1.01-1.17; P trend = 0.015). For individual RTFAs, we found positive associations with breast cancer risk for dietary intakes of two strongly correlated fatty acids (Spearman correlation r = 0.77), conjugated linoleic acid (HR for highest vs lowest quintile, 1.11, 95% CI 1.03-1.20; P trend = 0.001) and palmitelaidic acid (HR for highest vs lowest quintile, 1.08, 95% CI 1.01-1.16; P trend = 0.028). Similar associations were found for total ITFAs and RTFAs with breast cancer risk according to menopausal status, body mass index, and breast cancer subtypes.
Conclusions: These results support the hypothesis that higher dietary intakes of ITFAs, in particular elaidic acid, are associated with elevated breast cancer risk. Due to the high correlation between conjugated linoleic acid and palmitelaidic acid, we were unable to disentangle the positive associations found for these fatty acids with breast cancer risk. Further mechanistic studies are needed to identify biological pathways that may underlie these associations.