Assessment of potential risk factors for breast cancer in a population in Southern Brazil.

PURPOSE: The aim of this study is to assess potential risk factors for breast cancer in a population in Southern Brazil and build a multivariate logistic model using these factors for breast cancer risk prediction.

METHODS: A total of 4242 women between 40 and 69 years of age without a history of breast cancer were selected at primary healthcare facilities in Porto Alegre and submitted to mammographic screening. They were evaluated for potential risk factors.

RESULTS: In all, 73 participants among the 4242 women had a breast cancer diagnosis during the follow-up of the project (10 years). The multivariate analysis considering all the patients aged 40-69 years showed that older age (OR 1.08, 95% CI 1.04-1.12), higher height (OR 1.04, 95% CI 1.01-1.09), and history of previous breast biopsy (OR 2.66, 95% CI 1.38-5.13) were associated with the development of breast cancer. Conversely, the number of pregnancies (OR 0.87, 95% CI 0.78-0.98) and use of hormone replacement therapy (OR 0.39, 95% CI 0.20-0.75) were considered a protective factor. Additionally, we performed an analysis separating the participants into groups of 40-49 and 50-69 years old, since a risk factor could have a specific behavior in these age groups. No additional risk factors were identified within these age brackets, and some factors lost statistical significance.

CONCLUSION: The risk prediction model indicates that the following variables should be assessed in this specific population: age, height, having had previous breast biopsies, number of pregnancies, and use of hormone replacement therapy. These findings may help to better understand the causal model of breast cancer in Southern Brazil.