A comprehensive approach to breast cancer early detection in Pacific communities with high rates of obesity

Abstract

Breast cancer mortality remains disproportionately high among women in the Pacific region, driven by elevated rates of advanced-stage diagnosis, widespread obesity, complex ethnic mixture, and limited healthcare resources. This dissertation aimed to address these disparities by examining the interplay of obesity, ethnic mixture, and access to effective screening technologies in influencing breast cancer outcomes among Pacific Islander populations. In Study 1, clinical and demographic data from the Hawaii and Pacific Islands Mammography Registry (HIPIMR) were utilized to create a regional disparity index to classify risk profiles for each region and multivariable Cox proportional hazard models were used to identify significant geographic variations for overall breast cancer and advanced breast cancer. Based on the regional disparity index, we identified that women from Kauai or outside of Hawaii, and White women had higher risk profiles due to elevated proportions of high breast density. Women from Honolulu County had the lowest risk profile mainly due to being fairly lean, and being predominantly Asian. Cox models revealed that women from Kauai (HR=2.81; CI:1.15-6.81) and Maui (HR=3.15; CI:1.80-5.02) had significantly higher overall breast cancer risk compared to women from other regions in Hawaii. However, no significant associations were found between these regions for women with advanced breast cancer. Study 2 leveraged data from the Multiethnic Cohort (MEC) to investigate how ethnic mixture interacts with body mass index (BMI) to influence breast cancer incidence among Native Hawaiian (NH) women. Although age-adjusted incidence rates were highest among NH-only and NH/White/Chinese women (5.7 and 5.9 per 1,000 person-years, respectively) and lowest among NH/Other (3.6 per 1,000 person-years) women, these differences did not translate into statistically significant hazard ratios (HRs) in Cox models. Study 3 validated the clinical efficacy and acceptability of a novel, portable breast cancer screening device, the iBreastExam (iBE), among women in Guam, a representative Pacific setting with low-resources. Clinical validation, phantom studies, and patient surveys confirmed iBE’s utility as an acceptable device but had low clinical sensitivity (60%). Collectively, these studies inform and refine the Makawalu Paradigm, a culturally responsive and sustainable early detection framework specifically developed for Pacific Island populations.