S. Gopinath1, K. Mahendraraj1, R. S. Chamberlain1,2,3 1Saint Barnabas Medical Center,Surgery,Livingston, NJ, USA 2Saint George’s University,Surgery,Grenada, Grenada, Grenada 3New Jersey Medical School,Surgery,Newark, NJ, USA
Introduction:
Breast cancer (BC) is the most common cancer among Native American (NA) women. Despite this fact, existing data suggests NA women have a lower than expected BC incidence rates, but a markedly higher mortality to incidence ratio compared to other racial/ethnic groups. This study sought to analyze demographic and clinical factors in a large NA BC cohort to further investigate the validity of these observations and to delineate clinical and pathological factors which may better risk stratify this unique population for optimal treatment protocols and clinical trial accrual.
Methods:
Demographic and clinical data on 863,958 women with invasive ductal carcinoma of the breast was abstracted from the Surveillance Epidemiology and End Result (SEER) database (1973-2010). Standard statistical methodology was used.
Results:
Among 863,958 BC patients, 4,289 (0.5%) were NAs and 859,669 (99.5%) were Caucasians. The majority of BC in both groups occurred in those 60 to 79 years (43.7% Caucasians and 33.5% NA). NA women had a higher incidence of BC at a younger age (9.2% vs. 5.1% for age 20-39, and 51.8% vs. 38.1% at age 40-59, p<0.001), as well as a higher rate of regional (34.0% vs. 31.3%) and distant metastasis (7.9% vs. 6.1%). The majority of women in both groups had tumor size <2 cm (56.4%) and moderately differentiated disease (42.3%), p<0.001. Mean overall survival (OS) was significantly longer in Caucasian women than NAs (7.40±6.7 vs. 6.66±6.1 years), p<0.001. The majority (54.3%) of all patients underwent surgery only. Cancer specific mortality (21.7% vs. 21.2%) as well as 1- and 5- year cumulative survival (94% and 74% vs. 94% and 76%) was similar between groups. Multivariate analysis identified that age>60 (OR 1.3), size >4cm (OR 1.8) and distant metastasis (OR 3) were associated with increased mortality, p<0.001.
Conclusion:
Invasive ductal carcinoma of the breast affects the NA population far less often than Caucasians. NA BC patients tend to be younger and present with more aggressive disease features. Despite these finding, NA BC patients have survival equivalent to similarly treated women in other ethnic groups. Surgical resection and combination surgery and radiation conferred the greatest survival advantage in NAs. Due to its rarity, NA women with breast cancer should be considered for clinical trial accrual to further delineate genetic and environmental factors which may affect incidence rates and prognosis.
