Abstract P3-09-08: Overeating and breast cancer risk by pathologic subtypes: EpiGEICAM study
Authors: Pollán M , Castelló A , Martín M , Ruiz A , Casas AM , Baena JM , Antolin S , Ramos M , Garcia-Saénz JA , Muñoz M , Lluch A , de Juan A , Jara C , Sánchez Rovira P , Antón A , Chacón JI , Arcusa A , Jimeno MA , Bezares S , Carrasco E , Pérez-Gómez B , Lope V 
Published: February 2018

Introduction: It has been reported that overeating may be the greatest avoidable cause of cancer in nonsmokers and obesity increases postmenopausal breast cancer (BC) risk. Calorie restriction reduces BC incidence in experimental animals, but the evidence in humans is more limited. This study analyzes the association between female BC risk and excessive or restricted calorie consumption in Spain.

Methods: EpiGEICAM is a multicenter case-control study including 1017 matched pairs (age & town) of incident BC cases and healthy controls in 14 regions in Spain. Participants filled a structured questionnaire. Average calorie intake (cals) during the 5 years previous to diagnosis (cases) or interview (controls) was estimated using a validated 117-item semiquantitative food-frequency questionnaire. Expected calorie intake (cals_exp) was calculated from a linear regression model taking into account the basal metabolic rate (Sabounchi's meta-regression) and the amount of physical activity performed by each woman (5 categories). For each woman the prediction interval (99%) of cals_exp was used to consider her calorie intake as “normal” (NCI) (cals inside this interval –the reference group-), “excesive” (ECI) (cals&gt;upper limit of the interval) or “restricted” (RCI) (cals&lt;lower limit of the interval). The association of ECI and RCI with BC, overall and by pathologic subtype (luminal (ER+ and/or PR+ with HER2-), HER2+ and triple negative), was evaluated using conditional and multinomial logistic regression models, adjusted for age and region (multinomial models), education, body mass index (BMI), smoking, age at menarche & at first birth, menopausal status, previous history of benign breast disease, family history of BC, hormonal replacement therapy (HRT), physical activity and two scores reflecting the participant's adherence to Mediterranean and Western dietary patterns.

Results: After excluding participants with extreme calorie intake, 973 case-control pairs were considered. Average number of calories was higher in BC cases (1990 kcals) than controls (1897 kcals) P=0.001). Women with RCI (cals&lt;80% of the predicted limit) had lower BC risk (OR=0.52, P=0.001), being this effect more marked in premenopausal women (OR=0.36; Pheterogeneity=0.001). On the contrary, women with ECI (cals&gt;40% of the predicted limit) showed increased BC risk (OR=1.92; P=0.001), being this effect stronger in postmenopausal women (OR=2.81; Pheterogenity=0.001). By pathologic subtypes, no statistically significant differences were observed, but ECI (over 40%) was strongly associated with HER2+ tumors (OR=2.05, P=0.021). No differences in the effect of ECI or RCI were observed by levels of BMI, tobacco or HRT.

Conclusion: After taking BMI into account, excessive energy intake increases BC risk, while relative caloric restriction seems to have a protective effect. Moderate calorie restriction, in combination with regular physical activity, could be a good strategy for BC prevention.

Funding:Scientific Foundation of the Spanish Association Against Cancer (AECC), SEOM, FECMA, Cerveza y Salud Foundation, FIS CD110/00018

Citation Format: Pollán M, Castelló A, Martín M, Ruiz A, Casas AM, Baena JM, Antolin S, Ramos M, Garcia-Saénz JA, Muñoz M, Lluch A, de Juan A, Jara C, Sánchez Rovira P, Antón A, Chacón JI, Arcusa A, Jimeno MA, Bezares S, Carrasco E, Pérez-Gómez B, Lope V. Overeating and breast cancer risk by pathologic subtypes: EpiGEICAM study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-09-08.