THINK BEYOND PINK: An Epidemiological Assessment of Breast Cancer Risk and Survivorship in Jamaica, Ghana, and the United States

Abstract

Breast cancer represents the most common cause of cancer mortality in women worldwide.1,2 Incidence and mortality rates vary globally, due to differences in screening and treatment among developed and developing nations. Significant research has been performed on the molecular mechanisms that underlie tumor growth and metastasis. While this is important to understand the character and level of invasiveness of a breast carcinoma, there is a growing body of literature that seeks to illuminate the environmental factors that may predispose a woman to having breast cancer. From an epidemiological perspective, the following risk factors are associated with breast cancer incidence: age, oral contraceptive use, parity (number of childbirths), lactation, and nutrition.

This thesis research seeks to model breast cancer risk and survival in Jamaica, Ghana, and the USA based on the following main exposures: breastfeeding, parity, and hormonal contraceptive use. This modeling is founded on evidence extracted from global systematic reviews of these risk factors, their associated with age, and incidence and mortality.

Methods: Our sample included demographic data from Jamaica, Ghana, and the United States from which we extracted statistics on fertility rates, breastfeeding, parity, menstruation, and contraceptive use. From our literature search, we chose the following variables of interest: proportion of women who ever breastfed, proportion of women who are parous, and proportion of women currently using hormonal contraceptives. Using these statistics and each country’s population structure, we created models of breast cancer hazard (risk) and survivorship for the three-fold, two-fold, and one-fold effects of our variables of interest.

Results: Our models projected expected increases in breast cancer risk with age and associated declines in survival. We noticed the models in all three countries shift for ages 20, 35, and 50. The three-fold effect of breastfeeding, parity, and hormonal contraceptive use rendered the highest hazard and survivorship in all three countries. Specifically, Jamaica exhibited the lowest survivorship (0.53) in comparison to both Ghana and the United States. The age-specific hazards and survivorship for Ghana and the USA were largely comparable. Finally, we found the following main drivers of lowered survivorship differences between countries: hormonal contraceptive use in Jamaica, parity in Ghana, and breastfeeding the USA.

Discussion: Given that the three-fold effect of breastfeeding, parity, and hormonal contraceptive use gave the highest hazard and lowest survivorship in all three countries, there may be an interaction between our variables of interest that influence the underlying molecular and hormonal pathways in breast cells. Our models allow us to observe the specific factors that drive differences between Jamaica, Ghana, and the USA. This is important because it lays the foundation for addressing country-appropriate changes to breast cancer screening and treatment.