Risk Factors For Premenopausal Breast Cancer Among Latin American Women: The Precama Study

Isabelle ROMIEU, International Agency for Research on Cancer, France
RINALDI S. 1 , CARAYOL M. 1 , OLIVIER M. 2 , VILLAR S. 2 , PORTER P. 3 , GARMENDIA M. 4 , RODRIGUEZ A. 5 , SANCHEZ G. 6 , TORRES G. 7

1 Section of Nutrition and Metabolism, IARC, Lyon, France
2 Molecular Mechanisms and Biomarkers Group, IARC, Lyon, France
3 Fred Hutchinson Cancer Research Center, Seattle, USA
4 Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Chile
5 Fundación INCIENSA-Proyecto Epidemiológico Guanacaste, San Jose, Costa Rica
6 Facultad de Medicina, Universidad de Antioquia, Colombia
7 National Institute of Public Health, Mexico

-Purpose
Breast cancer (BC) is the most common cancer among Latin American (LA) women with a high proportion of cancer occurring among premenopausal women. Little is known about risk factors, especially for aggressive phenotypes. Therefore we are conducting a multicenter population-based case-control study to evaluate the etiology of molecular subtypes of premenopausal BC in LA.
 
-Methods
Cases and controls (aged 45 years or less) are recruited in Chile, Colombia, Costa Rica and Mexico, and matched on age and center. Standardized protocols are used to collect clinical and exposure data (reproductive history, lifestyle, anthropometry, diet, and environment), biological specimens, and tumor samples. Molecular subtypes are defined by immunohistochemistry analyzed at a central laboratory (FHCRC). Statistical analyses were conducted using logistic regression models adjusting for potential confounding factors.
 
-Results
To date, the study includes 466 subjects (268 cases and 198 controls). Sixty-one percent of tumors are luminal A, and 23% are triple negative. Parity, younger age at first or last pregnancy, breastfeeding , body mass index, waist and hip circumferences have a significant protective effect on BC risk. Intake of processed food (OR=1.43; 1.00- 2.05 per 1 portion/day increase), milk products, carbohydrates and fruits are associated with an increased risk of breast cancer, while vegetable intake (OR=0.88; 95% CI: 0.83-0.93  per 1 portion/day ) is protective. Moderate physical activity is protective while sedentary behavior increases breast cancer risk (OR=1.10 95% CI 1.02-1.18 per 1hr/week).
 
-Conclusions
These preliminary results suggest that lifestyle factors are involved in the incidence of premenopausal breast cancer in LA women. A larger number of cases and controls in the near future will allow determining risk factors for specific phenotypes and support target prevention and control of the disease.

-Funding source
Union for International Cancer Control; Pan American Health Organization; and International Agency for Research on Cancer.