Nutritional and environmental risk factors for breast cancer: a case-control study

AIMS: To investigate the associations between breast cancer diagnosis and nutritional and environmental factors in women from Northeast Brazil. METHODS: A case-control study included women evaluated in two hospitals specialized in cancer treatment. The case group was composed by women with breast cancer whose data were obtained during the hospitalization period for surgical treatment of the disease. The control group was selected in the same hospitals excluding the oncology ward. The following risk factors were investigated: household environmental sanitation, breastfeeding history, social class, smoking exposition, alcohol consumption and family history of cancer. A food frequency questionnaire was completed by the subjects and an evaluation of anthropometric nutritional status was made. Comparison for quantitative variables was performed using independent t-test or Mann-Whitney test. Chi-square or Fisher's exact test were used to compare categorical variables. The estimated risk associated with consumption of nutrients and food groups was assessed by OR, with a 95% confidence interval. In order to assess the effect of possible confounding factors such as excess weight or excessive caloric intake, a multivariate analysis was performed with the variables with p< 0.15 in the food consumption analysis. The significance level for all analyses was set at p< 0.05. RESULTS: The total sample consisted of 118 women, 59 in each group. Of all environmental risk factors investigated, poor sanitation (OR [odds ratio]=3.2, 95% CI 1.43-7.11) and family history for cancer (OR=3.11, 95% CI 1.42-6.78) were significantly associated with the diagnosis of breast cancer. Regarding anthropometric assessments, overweight or obesity and waist circumference > 88cm were more prevalent in the case group (OR=2.70, 95% CI 1.28-5.70 and OR=3.10, 95% CI 1.46-6.56, respectively). Regular consumption of ultra-processed foods was identified as a risk factor for breast cancer (adjusted OR=2.35, 95% CI 1.08-5.12). CONCLUSIONS: Higher consumption of ultra-processed food, presence of overweight or obesity, waist circumference >= 88 cm, poor sanitation, and family history of cancer were risk factors for breast cancer in this sample of women living in Rio Grande do Norte state, Brazil.