The role among metabolic syndrome and breast cancer risk is not well understood and must be further explored. The objective of this study is to evaluate the association between metabolic syndrome and breast cancer in Southern Brazil. In this case-control study, breast cancer patients and controls without malignant disease, matched for age (±5 years) and menopausal status, were interviewed and asked to make a glucose, HDL-cholesterol and triglycerides test. Waist circumference and blood pressure were measured using standardized procedures. Metabolic Syndrome was considered by NCEP ATP III (2001) and IDF (2006) definitions. Cases and controls were compared in relation to the presence of diagnosed MetS (yes/no), number of metabolic abnormalities identified (1 to 5) for each definition, and according to each metabolic abnormality cutoff point.

Inclusion Criteria:

• For cases: having newly diagnosed breast cancer without adjuvant or neoadjuvant treatment;
• For controls: having no evidence of cancer; be matched for age and menopausal status with controls

Exclusion Criteria:

• Women with a recidivated tumor, HIV infection, renal, heart or liver disease, hypothyroidism or hyperthyroidism, mobility or neurological limitations, chronicle use of corticosteroids, pacemakers or identified with severe edema were excluded.

Between December 2013 and August 2014, newly diagnosed (within 6 months) BC female patients referred to the oncology sector of the Teaching Hospital of the Federal University of Pelotas and to the Radiotherapy and Oncology Center of Santa Casa de Misericordia of Pelotas were invited to the study, before starting any adjuvant or neoadjuvant treatment. Women with a recidivated tumor, HIV infection, renal, heart or liver disease, hypothyroidism or hyperthyroidism, mobility or neurological limitations, chronicle use of corticosteroids, pacemakers or identified with severe edema were excluded. For each cancer case, one female control should be matched for age (± 5 years) and menopausal status (pre and post-menopausal). Apart from being free from all the exclusion criteria used for BC cases, controls should also have no signs of malignant disease. These women were invited to participate in the study while frequenting the Gynecologic Ambulatory of the same institutions, in the same period.