Risk Factors of Breast Cancer in Vietnamese Women: A study of Breast Density, Demographic, Reproductive and Lifestyle Factors

Abstract

Purpose: The aims of this thesis were firstly to explore the relationship of mammographic density, demographic, reproductive and lifestyle features with breast cancer in Vietnam; secondly to investigate the relationship of breast density with risk factors of this disease; and finally to examine the distribution of risk factors in northern and southern Vietnam. Methods: 345 cancer and 1,306 controls were gathered from the two largest cancer screening and treatment centres in the north and south of Vietnam in 2015. Data collection involved mammographic density, demographic, reproductive and lifestyle features. For the first and third aims, dissimilarities in the characteristics of cancers and age-matched controls were evaluated using Chi-squared (χ2) test and T-test. The impact of risk factors on breast cancer was evaluated through logistic regression. For the second aim, the association of breast density levels with elements were assessed using Spearman test for continuous variables and χ2 test for categorical variables. Results: In the first study, an increased risk of breast cancer was significantly related to women with extremely dense breasts, post-menopause, age at menarche ≤14 years old, less than 3 pregnancies and less than 2 babies born. Lack of physical activities was associated with breast cancer among pre-menopausal women. In the second study, increasing mammographic density was related to young age, low BMI, low number of pregnancies, early age at last birth, premenopausal status, smoking habit, drinking coffee <1 cup/day and consuming vegetables >2 servings/day. In the third study, women in the south had more breast cancer risk factors similar to westernized populations than women in the north of Vietnam. Conclusions: Breast density, several reproductive factors, coffee drinking and physical activities were associated with breast cancer in Vietnamese women and there were different risk factor patterns between the northern and southern regions.